Archive for the ‘Electronics stuff’ Category

Motors Demo

25 October 2017

motors-demo-20171025-2-cropped

I don’t use motors much in my projects, but they are everywhere now on our very mechanical world. So I am always running into them, and had a bunch set aside mostly from tearing down old printers. I have been particularly interested in stepper motors, as I had read about them a long time ago, and they are used a lot in industry.

Stepper Motors

This isn’t going to be a huge technical article, but: Stepper motors are used for positioning in all sorts of equipment, computer printers just being one example. They are designed to be moved an exact rotational amount (by counting the step signals sent to the motor) and to hold that position while energized.

The ordinary stepper motor is driven by two overlapping signals, as mentioned in my recent post about SerDes design. Finding new data about how these motors are driven inspired me to take another shot at creating a working driver. My previous attempt, based on sine waves amplified by audio amps, had not been successful.

Design by Numbers

Here is a rear view of my project, with numbers added to match the discussion below:

motors-demo-20171025-4-cropped-annotated

  1. AC terminals and connectors. I like to run my projects off AC-powered supplies. I get them cheap from thrift stores. Usually they are “wall warts” or otherwise portable / external power supplies, and I remove the plastic cover and use the board inside. Sometimes I keep half the cover if it helps for mounting purposes.The funny thing about all modern power supplies is that the first thing they do is convert your AC power to DC. Then they step down the DC (about 120V in the US, about twice that in many other places) to the power supply voltage. Most of these modules provide good regulation, because that’s built into the controller electronics, and it helps protect people and equipment.
  2. I stacked the two power supplies I used. The top one runs my control electronics. Most of it is 5V, but I also have some 12V relays.
  3. I used a 9 volt 3-1/2 amp module to run the motors. These are a little hard to find, so when I run across one I grab it for later use. 5V supplies are ubiquitous, as they are used now for phone chargers (phones generally have 4V batteries). But other voltages and power levels can be more scarce.
  4. Next in line is a board that monitors the motor supply for voltage and current output. You can buy panel meters with these features built in, but I built my own, as it’s not too hard. It then feeds generic panel meters. The hardest part to get right on this board was the current shunt. I used a bunch of SMT (surface mount) resistors in parallel.
  5. The motor driver module was purchased online from China. This particular one had some problems, and I basically had to repair it before I could use it. That sometimes happens with cheap stuff from China. They had installed the wrong part to function as a 5V auxiliary supply. It was supposed to be a fixed-voltage part and an adjustable-voltage part was installed. So I had to lift the adjustment pin off the board and add some components to get my 5V output.One of the drivers was also poorly soldered, so I went over the solder joints and added more solder as needed.

    The board uses a part that has been around for a long time (LM298). It is designed to drive stepper motors. It has four logic-level inputs (plus enable) and four power outputs. It can work up to 48V. I had planned to add a second higher-voltage motor driver supply to the project, but all the motors worked fine with 9V, so I left it out.

    You have to feed the driver the correct signals, and I made two more boards to do that. One board provides the four steps needed to generate the “quadrature” drive pattern and a pulse-width-modulated (PWM) signal to vary the amount of drive. The other board converts these signals to those needed to feed to the driver board.

  6. Another board just gets all the connections right.
  7. I used a four-position rotary switch to select between four different motors. Only one is a stepper motor. The ordinary DC motors are very easy to power on; you just apply power. You can modify their speed somewhat by changing the drive voltage or using a PWM signal which essentially does the same thing. I used one driver IC on the driver board to power the DC motors. I paired up the four drivers to make two. I can run the load in forward, reverse or braking mode.
  8. Here are the front panel controls for stepper speed, PWM, and forward – brake – reverse.
  9. Cheap panel meters from China indicate the drive voltage and total current being used. They have a nice auto-ranging feature which makes them usable up to about 50 volts input. Their electronics run on 5 volts. These digital meters only have three decimal places, but that was enough for this application.

Closing Comments

The biggest problem with motors is having them stall out due to mechanical overload, which can ruin both the motor and the drive electronics. As these motors are running no-load, that’s not a problem. You can grab the motor shaft with your fingers if you want to, and see what mechanical loading does to the current draw. But for real use, the electronics should include overcurrent protection to turn the power off if the motor stalls. Many industrial motor drivers also monitor motor temperature, which is another way to tell that something is going wrong with your motor.

I am very happy that I was finally able to get my stepper motor to run (both forwards and reverse!) and at a variety of different speeds. It turns out steppers are a bit sensitive to what speed you drive them at. Try to go too fast and they just won’t run. Go too slow and they use too much power (though there are ways around this). Most steppers have an optimum speed, and in most applications, you will see them operated at a constant speed, or maybe two, high and low (like in a scanner).

The driver module was designed for robotics hobbyists. It’s a neat design, but not well-documented. I had to look up the datasheets for the various parts used to get details. This is par for the course in hobby electronics.

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In search of a better SerDes

17 October 2017

Oh no! Another dry technical article! True, true. Just pass it by if you’re not interested.

Serdes sounds like a Greek word, but it isn’t really. There are some people with the name Serdes, but it is uncommon. I learned it as an engineering acronym thus (lightly edited):

A Serializer/Deserializer (SerDes) – usually pronounced “sir-deez” – is a pair of functional blocks commonly used in high speed communications to compensate for limited input/output. These blocks convert data between serial data and parallel interfaces in each direction. The term “SerDes” generically refers to interfaces used in various technologies and applications. The primary use of a SerDes is to provide data transmission over a single/differential line in order to minimize the number of I/O pins and interconnects.

https://en.wikipedia.org/wiki/SerDes

Electronic Art

I am trying to work out some cool things to do with LED arrays that would respond to environmental or observer inputs. There are many pieces to such a system. This includes the possibility that the display itself may be some distance from the electronics that collects the input signals and decides what the display should do. The same way a computer monitor can be separate from the computer. And in this case, the two are connected with a cable.

Some of us remember the old printer cables. They were thick, had up to 25 separate wires in them, and couldn’t be much longer than 15 feet. I could probably use such a cable in my projects. But that’s a lot of bulk, and it comes with many limitations. Those cables connected a parallel port on the computer to a parallel port on the printer. There were usually 8 data lines plus a bunch of handshaking signals to make it so the computer would not send data faster than the printer could print it out. If you wanted to get a lot of data back from the printer, you could add another 8 data lines going in the opposite direction.

8 bits can encode into 256 different numbers (0 to 255). That’s enough for an alphabet – both upper and lower case – and a bunch of other symbols. Each symbol has a number “code” that stands for that symbol. Both ends of the line have to use the same code system.

An 8 bit parallel system could go pretty fast; millions of symbols per second. But try pushing parallel data through a long cable that fast and you will quickly run into problems. You would need to shield the cable so external signals won’t interfere with it, and so it won’t radiate signals into external equipment. And the wires in the cable, when they get quite long, resist fast signals going through them in at least three different ways (resistance, inductance and capacitance). So if you want to send data fast through a long cable, you have a whole hardware design challenge on your hands.

SerDes concept

Illustration of the SerDes concept. Original graphic by Grégoire Surrel – Own work, CC BY-SA 4.0

The solutions to these problems usually involve reducing the number of wires carrying signals (ideally just one pair would be enough) and creating special hardware interfaces that alter the signals so that they will make it through the cable successfully, even though the cable presents various barriers to proper transmission.

A standard solution for many years was the “RS-232” serial cable. In this system the signal is amplified to make it more resistant to interference and cable attenuation. And the signal is “serialized” so it only has to use one pair of wires. That means each symbol of 7 or 8 bits would be transmitted as a sequence of bits that would have to be reassembled into 7 or 8 parallel bits at the receiving end. That was an early SerDes system. But we didn’t call it that in the old days. The acronym only came into wide use after the internet and its various forms of information exchange came into wide use. The term commonly refers to high speed data transmissions, but the basic concepts are the same regardless of data rate. My projects use quite low data rates just to make sure I don’t run into too many design problems and can use cheap parts.

The RS-232 standard could probably work for me, but I wanted to try another more modern data transmission standard, TIA-485. (RS = Recommended Standard, as published by the EIA, Electronics Industries Alliance, but now taken over by the TIA, Telecommunications Industry Association). This standard uses two wires for each signal plus a third wire used as a ground (zero volts) reference. The signal is transmitted in an attenuated form, differentially. That means a “zero” would be transmitted by putting maybe 3-1/2 volts on one wire and 1 volt on the other. And a “one” would be transmitted by reversing those. Smaller signals in a cable create less external interference and are easier to pass through longer cable lengths.

I have a connector that is used for MIDI (Musical Instrument Digital Interface) that has five pins, which means it can carry two differential serial signals (or 4 RS-232 signals) plus a ground reference wire. I wanted to use this connector and a 5-wire cable, but there was one problem:

SerDes Timing

Just as in the old parallel printer cables, where handshaking signals were necessary to tell the printer when a symbol to print was put onto the connecting cable, and tell the computer when the printer was busy, serial systems also need a way of at least telling the receiver when the transmitted data is good, how fast it is going, and when an entire symbol has been sent. This requires, minimum, clock and end-of-symbol signals for data rate and data synchronization. In the RS-232 system, the data rate had to be set at both ends in advance. And the end-of-symbol signal was coded into the data stream. It takes a computer to figure out how to decode this data stream, but if you send all three signals separately, you don’t need any computing at the receiving end. Deserialization can be done with one piece of hardware called a shift register.

But I can’t transmit three signals over a five-wire TIA-485 cable, only two. So I thought I’d figure out how to combine the three signals into two so that my system could work with the hardware I have. I devised a rather simple system to do this, and built an initial working system several years ago for my “Christmas” project (Christmas because it used strings of holiday lights for the visual display). Recently I have built two more systems that use this method.

Glitches

I like to re-design systems each time I build them. This is partly because I might not have the same parts available that I used in an earlier design. Or it might be just to explore different ways the problem could be solved. All the heavy work in my SerDes system is on the transmitting site. The receiver is very easy to make. And for this transmitter design I wanted to use counters to run ICs (integrated circuits, now often known as “chips”) called multiplexers. You put parallel data on the 8 inputs of a multiplexer, then tell it which input to put on the output using a counter. And if the counter repeats a regular pattern (as most do) then the parallel data at the inputs will come out of the output in a predictable serial sequence. And so you have achieved serialization.

In my first design I was getting “glitches” at the outputs of some of my multiplexers. This is because I was using “ripple” counters. In this type of counter, the counting outputs don’t all change at exactly the same time. They might be a little off (usually much less than a microsecond, but that’s enough time to cause trouble). In other words, when changing from count 1 to count 2 for instance, the ones bit has to change from one to zero, while the twos bit has to change from zero to one. If the twos bit lagged a little, both outputs might be zero for a split second, telling the multiplexer to go to the wrong input. Such glitches can be filtered out, which is what I did in the first design. But in the second design I decided to try a different counting scheme, where only one counting bit would change at any one time. This should make counting glitches impossible (it does). But it means the count is no longer in number sequence. In other words to do this with a 4-count pattern, you have to use the pattern 0-2-3-1 (or 0-1-3-2) to get a glitchless count. This different sequence is not a problem when using a multiplexer, though it is more confusing to design if you are used to using ripple counters that count 0-1-2-3 (etc.).

I looked at the waveforms associated with this kind of counting, and they were just two square waves offset by one count. I found a PDF online that describes how to implement this kind of counter. It’s called a “quadrature” counter, and it’s pretty simple to do. Getting a similar sequence of 8 is a little more tricky, but basically just interleaves a quadrature signal with a square wave. I built my second system this way and it works fine (though I had to scratch my head a bit to get the input sequence right, as it is sensitive to the place value given to the various counting signals).

quadrature waveform illustration

A four-count pattern implemented using a quadrature counter.

What form should the data take?

So I now have a hardware system that can be used with either 2 TIA-485 signals over quite long distances (if the cables are made well) or with 4 RS-232 signals (but not the RS-232 encoding system). The RS-232 version is much easier to build, but does have distance and speed limitations compared to the TIA-485 system.

The original intention of the system was to enable transmission of 8-bit-wide signals that would be used to control an array of LEDs. But it could also be used to transmit serial control streams of any bit length. This means a wide variety of displays could be controlled, as long as they didn’t have to change at a very fast rate. In other words, we’re not talking about full-motion video, like TV, but that’s not the sort of display I’m working with. My average display contains less than 100 LEDs, while a modern TV screen contains millions.

I have also tried transmitting analog data using digital serial techniques by using pulse-width encoding, which is very simple to implement in hardware. This gives me the option of using digital data transmission instead of long analog signal lines. This may come in handy in some of my projects.

Electronics Design Case Study – ADSR

23 September 2017

ADSR module homemade

This is a technical article and if you have no particular interest in electronics design feel free to skip it. It will get into some terminology that won’t all be explained in the text…

Music Synthesis

My interest in synthesizers goes back to my early days studying electronics. I always wanted to make my own synth.

But by 1983, MIDI had come out, and I was in the Sea Org.

MIDI stands for Musical Instrument Digital Interface. Musical instruments were an early target for embedded controllers (software-controlled electronic circuits) for many reasons. This ended (mostly) the era when synthesizers were controlled by analog (continuous) signals. Voltage sources were terrible when it came to keeping all the electronic instruments in an ensemble in tune with each other. So tuning was an obvious feature to turn over to the digital world, where crystal-controlled oscillators could stabilize pitch to within a few parts in a million.

The advent of digital signal processing meant things like voltage-controlled filters and unusual effects like ring modulation could be implemented with algorithms instead of hardware.

Voltage-controlled amplitude, however, is so straightforward in the hardware realm that it remains somewhat popular. A basic part of synthesizing a real-world note or sound is approximating its amplitude envelope. This envelope has long been analyzed by acoustics engineers into four parts: Attack; Decay; Sustain and Release. If you play a note on a stringed instrument you can easily see each of these parts in action. How hard and fast you hit (or pluck) the string determines the initial attack and to some extent how that attack decays. Then if you don’t damp the string it will continue to ring until it is damped or played over. This is sustain. And when it is damped, the sound will die out, which is the release phase.

There are many many possible ways to imitate this amplitude envelope with electronics. The most common methods use parts that I had run out of (1 Meg-ohm potentiometers) so I decided to try an alternative design of my own creation.

Design Requirements

Most traditional ADSRs take a “gate” signal from a keyboard which tells the electronics how long the key is being held down (“note on” in MIDI). My electronic art projects use sensors, not keyboards, so I couldn’t rely on a gate signal to determine how much sustain the sound would have. I also kind of wanted a circuit that could be adapted so that each part of the envelope could be controlled by a separate sensor. That means it couldn’t just use pots, like the super-simple designs do. I also wanted to try straight-line segments rather than the traditional curved segments you get using just resistors and capacitors, even though this is less “realistic” for decay slopes.

I had a front panel I was reusing from an earlier project, and originally loaded it with just three pots – all that seemed to fit – which is two less than you need to control the five main parameters of the envelope. But I thought I could skip setting a sustain level, and use one pot to control both decay and release slopes. This panel had to fit into a eurorack-style chassis I had put together earlier, with power coming in the front.

The unit was also to include the voltage-controlled amplifiers, using an IC I had never worked with before.

First Try

I decided to use an op amp integrator at the core of the design, as it would give straight-line slopes and could be dependably controlled. However, I wasn’t sure how to set up my 100K pots to imitate a wider range of resistance. I used three comparators and a couple of flip-flops to detect voltage levels and turn the various slopes on and off.

Mounted at the bottom of the front panel was a backplane board that has become standard in most of my designs. Circuit boards then plug into this backplane, which ideally handles all the interconnects. Front panel parts that could not be mounted directly on the backplane board would be wired down to the backplane using jumpers.

I made the envelope generator board first and then the VCA board. The VCA datasheet was confusing at first, but by wiring an actual circuit I was able to figure out what was going on. This VCA could accept a wide range of control voltages (0 to 30 roughly), but they were referenced to the negative voltage rail! So I needed both an amplifier and offset for my envelope, as it would go from 0 to 5V only, my standard range for control voltages. I realized at this point that I would need a sound source to test this with, and it would also be nice to monitor the envelope waveform on an analog meter. I then spent about a day creating an oscillator and a meter for these purposes.

An incomplete design with too many questions about “will it work this way?” resulted in my running out of room on my envelope module. To solve this I piggybacked an extra module onto the main one. I got some sort of envelope out of this design, but the pots worked only over an extremely narrow range of their total rotation. I had to decide whether to stick with these pots and basic design, or start over.

Second Try

I looked around at what my alternatives were. I had a nice set of six quite small 5K pots from an old piece of audio equipment. They would all fit into the panel if I drilled new holes for them. So I decided to go for it. Five of these pots went onto a new backplane board. I modified this board to hold circuitry and figured the majority of my new design would fit on this board, with the rest put on a new plug-in module on the original backplane.

Now that I was beginning to recognize that this was a challenging project, I went to a build a section and test it approach to my work. 5K pots could only yield 1:100 output variations (comparable to using a 1Meg pot in series with a 10K resistor) by using the turn-on “knee” of transistors to stretch out the transfer curve. I have used this before so didn’t bother to work it out in complete detail, or plot the curves graphically, but below gives you a graphical idea of what I’m referring to:

transistor turn-on graph

Using a curve found on the internet, note that a 0.1 change in input voltage produces a ten-fold change in output current. Extend this input range a little more and you can squeeze out a 1:100 input/output ratio, or even more.

I built my current sources and sinks using discrete transistors. This gives worse consistency and stability than using matched pairs or some specialized IC, but usable for my purposes. I built one and tested it. I gave me a range of 50 to roughly 1500 microamps. This was good enough. I put the rest on the board, then added a dual timer (LM556) and some inverters and connected it up to run continuously (astable mode). I powered up and checked with my oscilloscope. This part of the design worked fine. The timers have two comparators and a flip-flop inside each of them, so this decreased my parts count.

I thought that I could get the timers to stop after just one cycle using some sort of edge detection scheme. But it didn’t work. I was using two timers so that the attack-decay and sustain-release cycles were separate and could be put in sequence. But my difficulties in making the circuit cycle just once and stop caused me to rethink this approach.

The next day I rewired the timers for one-shot (monostable mode) operation. Now the timers could be triggered by my sensor, fire – producing the envelope waveforms – and would then stop, waiting for a new trigger. I used two control flip-flops with NAND gates (CD4093B) to lock out new trigger signals until the current envelope had finished. I really needed only one flip-flop, but the package (CD4013B) has two in it, so I used one for each of the timers.

Next I had to get all the analog levels of the envelope right. I put this circuitry on the new module board. I only needed 8 wires to connect the new envelope module to this analog module. It has six opamps and a comparator. The comparator detects when the envelope signal goes to zero, and resets the flip-flops so they can allow in another trigger signal. This circuit wasn’t working at first. What was wrong? The envelope waveforms were only going down to 0.5 volts, not to ground. I had the comparator set below this, so it was never firing. I was powering my envelope generator with only ground and +12V. The current sinks (set up as mirrors for my current sources) could only pull the load capacitors down to 1/2 a volt. I compensated for this by adding some offset to my summing opamp. I set the output to go a little below ground so the comparator would for sure fire. I had to find a missing wire on the envelope board before I got the unit totally working. It’s not perfect, but it now works as it was designed to work, and will serve it purpose in helping me develop electronic art that uses sounds.

Legacy Pan-Tilt for Video Camera

22 April 2017

pan-tilt for video camera

pan-tilt side cover removed

This piece of “legacy” tech isn’t much to look at. It was the first item I photographed but the last I am making a post about.

I got it from my brother when his company upgraded all their video equipment to more modern stuff.

This was possibly made to sit on a pole and hold one of those large surveillance cameras that you still see some places. But this unit was being used inside to hold a camera much smaller than it is (though heavier than modern cameras that are fully electronic).

pan-tilt with main cover removed

It originally had a long control cable so it could be moved around from a remote location. The controller (shown underneath) simply switched the motor drive voltage (about 24 volts AC) between four different drive windings on two different motors – forward and reverse for each motor. There are little switches installed in the housing to turn the motor off if it tries to move beyond the mechanical limits of the housing. And that’s all there is to it.

With the advent of much smaller cameras, pan-tilt units no longer need to be this large and heavy.

Voltage Divider Assembly

10 April 2017

voltage divider assembly inside
A few years ago I purchased a pair of differential voltmeters because I was looking for aluminum equipment cabinets and thought these might work. The front panels were actually a full 1/4-inch think, which was a little more than I bargained for. These were military-grade equipment, and I think both of these items had been in use by the Army.

I got them from Fair Radio Sales “as-is.” The shipping cost almost as much as the equipment did. These meters were made by John Fluke Mfg Co, Inc, of Seattle in the early 1960s. They used mostly vacuum tubes and various other technologies now considered Legacy. The idea behind a differential voltmeter is that you compare a known voltage with an unknown one, and use a meter to tell when they are equal. The settings you used to get the known voltage are then equal to the voltage you wanted to measure. Ponderous. Today’s digital voltmeters do the same thing, except they “turn the dials” for you and present the result on a readout screen.

voltage selection dials

Marked dials function as an old-school digital readout.

This assembly is just the voltage divider for the known voltage. It consists of a set of switches and precision resistors arranged so that when you put in a reference voltage, the output equals the voltage you dial in. For accuracy, the resistors used have to be high-precision. These ones have a tolerance of +/- .02% which these days is unheard of. I saw a refurbished working version of this equipment for sale for over $1,000. It’s considered an ultra-precise laboratory-grade device.

inside the voltage divider

From what I can tell this equipment was entirely hand-assembled. That was how it was done in the “old days” of electronics. The colors involved are kind of pretty but they also served to help the assembler be sure he or she had the right part or was sticking the right wire in the right place. All the resistors were made of lengths of fine wire wound onto forms then glued in place with clear paint. Fluke may have constructed the rectangular ones themselves. The yellow cylindrical ones were made by an outside firm.

voltage divider back side

I couldn’t get over the workmanship put into these components, so I kept one of them. But this one is now extra and is destined for the recycling center.

High Voltage Divider

8 April 2017

100KV high voltage divider

Here’s another piece of “legacy” technology. However, in this case the manufacturer, Spellman High Voltage Electronics Corp in New York, still offers this device as the HVD100. This is the smallest model, for up to 100K volts. That’s 100,000 volts. The input voltage can be monitored at a ratio of 1,000 to one, or 100V full scale, or at 10,000 to one, for 10V full scale. The total resistance of the column is 1,000 Meg ohms or 1 Gig ohm.

I bought this unit on eBay as basically a piece of junk. I was curious what it was, as the description wasn’t clear. It arrived slightly damaged. I disassembled it and altered it a bit to strengthen it and make it easier to take the top and bottom electrodes off. All the rounded parts are for the purpose of reducing arcing. Arcing will interfere with measurements, creating momentary lower-resistance paths across the device. However, the top and bottom electrodes make it really clumsy and difficult to transport. It is designed for laboratory use, and includes a sparse but descriptive label and BNC connectors to attach measuring equipment.

high voltage divider detail

As with many of the items I have kept around, this one has a certain aesthetic value, but I never use it. Though I find high voltages exciting, they are difficult to produce and dangerous to handle, and really beyond by current experimental capabilities.

Depth Sounder

3 April 2017

Here’s another piece of equipment destined for the dustbin (or in this case, electronics disposal center). I found this a few years ago at the Goodwill Outlet in Seattle. As far as I know, it is totally functional.
It does, however, lack the transducer needed to make it work on a boat.

legacy depth sounder

Location by Echo

Radar, Sonar and related distance-finding technologies all operate on the basis of echo-location. It’s a clever system, because you can measure both distance and direction from just one point. With visual methods you need two or more points to view from so you can triangulate.

In the case of this device, the transducer is fixed to the bottom of the boat, so it only points down. Thus, “depth and fish.”

Whereas cheaper versions are geared only to tell you how much water you have under your keel, this one is rigged to display multiple echos from different depths. Judging from the difficulty I had in finding the user’s manual for this instrument, I would guess it was built and sold before internet shopping became popular. Modern versions still operate on the same principle, but are computer-based.

Here’s the electronics:

depth sounder electronics

Relatively simple. It operates on the boat’s battery, 12 volts. There’s a connection for the transducer (I moved it from the back). There’s a motor to spin the lighted indicator, and some logic circuits. If you’re into electronics, you’ll also notice some RF (radio frequency) parts on the board. Per the manual, the transducer operates at 200KHz. That’s RF, and as sound, classifies as ultrasound. It’s ten times higher frequency than what we can hear with our ears. I don’t know about fish.

Toroid Transformer

26 March 2017

This is the first of a short series devoted to items of technology I have run across in my pursuit of my electronics hobby that were once “cool” but are now seldom used. Most of the things I will show here are destined to be thrown away or otherwise disposed of, as I have found no use for them, either.

The Toroid

The toroid is a big deal in some branches of New Age Physics and is a significant concept in regular physics as well.

Technically, “toroid” describes the shape of a torus or similar geometric object. It is, however, used as a noun. The shape is, colloquially, a “doughnut.”

Coils wound on toroid cores have been around for a long time, as they have certain advantages to cylindrical coils or square transformer forms. The magnetic field they generate tends to stay inside the core, so they emit less electromagnetic interference.

Toroidal parts are a little tricky to manufacture, but the need for them has become so great that they are now commonplace. However, 60Hz (or 50Hz) power transformers are a rarity in electronic equipment nowadays, having been replaced by high-frequency transformers. They are still used in electric power systems.

My Transformer

toroidal-power-transformer

This transformer came in a video distribution rack made by a company called Sigma, probably around 1995. The primary takes line voltage (120VAC) and the secondary outputs about 30VAC with a center tap. It was used to make a +/- 15V power supply. That power was fed to amplifier modules that created +/- 12V rails using on-card linear regulators. The amplifiers were high-power op amps connected in current mode. They only needed a voltage gain of 2. Each card had two. This was for old composite video. Composite video is out of style now, so all the equipment that was made for it (and there was a LOT!) is now just this side of junk.

The future of legacy technology

Does old technology have a future? SciFi writers have speculated about this. What if this planet gets downgraded and we can’t make modern technology any more? Would older “junk” technology help us recover? And what if we travel to a distant planet that turns out to be less advanced than ours? Would it help to have an older technology available that would be usable there? These are actually ancient questions, but not even LRH ever really goes there. It gets mentioned in accounts of ET history every now and then. If the true data about Antarctica ever gets released, it would be quite a revelation, and this question comes into play in those ancient events.

But I must say, this thing weighs about 5 pounds and is now replaced by technologies weighing less than 1 pound. You could never take it into space using our rockets. But should I keep it as a novel paperweight?

toroidal power transformer upright

It is somewhat interesting to look at.

I just got chipped.

24 July 2016

mastercard promo piece

A replacement debit card arrived in the mail today. I got an email from my credit union saying it would be coming. It has an electronic integrated circuit “chip” in it that is supposed to make transactions more secure.

Well, fine. Who cares? They are trying to deal with all the credit card fraud going on around the world.

But for anyone familiar with the alternative realities community, this connects directly to something Aaron Russo and many others were talking about for a long time.

The whole agenda is to create a one-world government where everybody has an RFID chip implanted in them…there will be no more cash — and this was given to me straight from [Nicholas] Rockefeller himself…
– Aaron Russo from 2006 Alex Jones interview

Russo died in 2007, five years after learning he had cancer.

The current experimental model, which has been reported on television and implanted under the skin in many people, is not exactly a “chip.”
public version of RFID chip
It’s a tiny tube with some electronics in it, and a pickup to energize it when it is scanned, like other RFID technologies.
RFID chip diagram
The implant contains only an ID number or code. This is fed into a computer which connects to one or more databases that might contain more data about the person. A pilot program in Atlanta was using it to connect to a medical database to help with emergency treatment situations.

ET

It has been stated by numerous researchers and experiencers that real (and “faked”) ET abductions often include insertion of an implant. When these are found (by x-ray usually) and surgically removed, they are usually described as “biological” or “bio-electronic.” That kind of implant is certainly more sophisticated than what we are seeing in the mainstream media. And reports say it is much more invasive, too.

How important is this?

These devices are certainly real. The low-tech versions pictured above have been released to the public, and other versions have been studied.

To the extent that they can be implanted without the knowledge of the carrier, they can be used as a covert method of tracking people. And their capabilities could include mood alteration, thought control or fake telepathy, and triggering of hypnotically-installed programming.

But to the extent that they can be detected and removed or deactivated, they are not a reliable control technology. Of course, we could be forced to use them, as people are forced now to take vaccines. But that would be a too obvious totalitarian ploy. So I don’t think they will come into wide use unless the totalitarians gain a lot more control than they have now.

The chip in my new debit card, however, is another matter.

As a long article at Wikipedia explains, the card issuing institutions (a few major banking companies) are forcing businesses to upgrade their card processing equipment (also known of Point of Sale equipment, or PoS – confusing because this acronym is already in use to mean “piece of shit”) by re-writing merchant contracts to stipulate that merchants will be responsible for all fraudulent transactions on non-upgraded equipment.

Meanwhile, many cyber-security researchers have tried to demonstrate that the new equipment can be fooled just like the old equipment could be. But the banks are having none of that; they are pushing ahead with what looks like a target date of October 2017 for full implementation.

My take is that bankers at the consumer level have become desperate. Their technologies are hackable and it is costing them money. Even after they stopped paying consumers interest on their savings, and though they charge very high rates for purchases on credit, a general surge of financial crime is continuing to squeeze them.

I think it is quite possible that criminal elements in the banking system are trying to force a collapse in consumer banking by pushing weak-security-by-design technologies, then financing the credit card hacking industry. People are just having too much fun with their credit cards. And this whole “false flag” paradigm has become such an obvious modus operandi for well-placed criminal groups in recent years, that I have come to suspect it is in use whenever I see a suspicious “problem” like this one persist. I am just guessing in this case, but the possibility for something like this is very real.

The use of the term “gold chip” is at one level a marketing stunt and at another level a slightly sinister play on words. This could be the “chip” that Russo was told about! Take away cash, or make it very scarce, or worthless, and a card with a “gold” chip in it will be the only way left to transact business in the “legitimate” economy. Back to the days of Roman gold coins!

The criminals have the consequences of their actions totally justified. They don’t respect what little dignity human life has left. They hate it and themselves. It is much more important to realize this and out-create this suppression than it is spread doom-and-gloom about our future. The doom-and-gloom are inevitable if we don’t out-create the suppression. So why dwell on it while we still have a chance to escape it?

And as for ET and their implants? I recommend the same basic approach. Treat them as criminals until they reveal themselves and prove otherwise. It’s probably the truth in most cases.

Electronics Project – Technical

21 December 2015
V-I box front panel

Front panel for my “V-I Box” – reused Extron video equipment.

This is a technical article about a project I recently finished (for the most part). It doesn’t work that well, but it is quite complex so gives me a chance to cover several topics while talking about just one project.

V-I Box

V stands for voltage, named after Volta, an Italian.
I stands for current (French intensité de courant) as used by the French scientist Ampère.

In electricity and electronics, any component will have a characteristic “V-I Curve” showing the relationship between voltage across the component and current through the component. These days, we usually use “curve tracers” to get this graph, but you can also plot it a point at a time using a variable power supply.

Last year I had constructed such a variable supply for a little presentation I gave at work about transistors. Later I made another one to use to demonstrate the operation of vacuum tubes. I wanted to preserve these projects (and the parts used in them) in a more compact space, so I decided to squeeze them into an old Extron (video processing equipment maker headquartered in Anaheim CA) enclosure. The photos show what resulted.

The design is far from ideal but retains most of the features of the older designs, while making some changes to increase the current capacity of the lower voltage source and keep part of the Extron front panel.

Following is a discussion of some of the features of this project.

V-I box guts

Inside my project…

Creating a 1-250V variable supply

I was not prepared to create a supply that could ramp from 1 volt to 250 volts in one smooth transition, so had procured several power supplies, 4 50-volt supplies, a 25-volt supply, and a 1-25 variable supply in the form of a DC-DC converter.

I then had to create logic that would switch through the supplies in 25-volt steps. As part of this scheme, the supplies are put in series (or “stacked”) with each other. This is only possible because most power supplies (not some of the old tube ones, though) use isolation transformers so that the output and input can be at different DC levels. This isolation usually works up to at least 1,000 volts.

The high-voltage sub-system receives a binary code (from 0 to 255) and must decide how to connect the supplies to get a supply voltage about equal to the value of the code supplied.

To implement this I used 4 relays using 5-volt coils, so I could use logic signals to switch the voltages. The DC-DC converter was a cheap one using a potentiometer to set its output value. To make it variable by remote control, I had to set up a control loop using an op amp to drive an optical isolator. The output transistor of the isolator would server to replace the potentiometer.

Other voltage sources

My earlier designs had two other voltage sources, one to bias the tube grid or transistor base or gate, and another for the tube heater. I used a low-power op amp to supply the bias voltage, as hardly any current drive is needed, and I thought +/-10V would be a sufficient range.

I had used a variable linear voltage regulator for the heater voltage, but in this design decided to leave that out and just make my 5V control electronics supply available for that use.

I also needed a supply to run my DC-to-DC converter. It is a buck converter, so I needed greater than 25V. And I only had +/- 12V rails and +5V available from my control electronics power supply. So I used a boost converter driven by the +12V rail to get about 30V which I fed to the buck converter.

Measuring voltages

Providing panel meters for measuring instruments is always a challenge. Today the most common design uses a microcontroller with an A-to-D (analog-to-digital converter) driving an LCD (liquid crystal display). However, I had already purchased a bunch of little modules for the earlier boxes and wanted to use the. So I fit four of them into the new panel. All they do is display the input voltage when powered by at least 5V. These modules have about 370K input resistance and can display up to 99.9 volts. You can get all kinds of different ranges. As I wanted one display to show the entire range of output voltages, I had to divide the input by ten and settle for 25.0 maximum readout. The other module is used for the 1-50V segment of the output supply, and operates at full 3-digit precision. The bias voltage is displayed on the LCD that came with the original equipment.

Measuring currents

In modern electronics, currents are always measured by converting them to voltages first. The old analog current meters responded directly to input current. To convert a current to a voltage, just pass the current through a known resistance, then measure the voltage drop across the resistor. This may then be amplified if needed. In my case, I needed to amplify the signal so that I could use my little voltmeter modules as current meters. (You can also get modules that have this capability built in.)

For the “heater” (+5V supply) current, I used a 0.2 ohm resistor. This would drop 1 volt at 5 amps, so I needed to amplify it to give my meter a range of up to about 3 amps (reading of 30.0). I used an op amp in “quasi differential” configuration to get this reading, so I could put the resistor in the high side of the 5V rail.

For the main supply I used a 4 ohm resistor, as I expected to draw only about 30ma maximum (30.0 reading) from this supply. 30mA through 4 ohms gives a voltage drop of 120mV, so I had to amplify this by a gain of 250. I used an op amp in non-inverting configuration for this purpose.

I used the 30V supply driving my DC-DC buck converter to power these op amps. This was close to their maximum supply rating of 32V!

Front panel controls

The front panel that came with the Extron equipment had an LCD, some pushbutton switches, and 4 little knobs. The knobs felt like potentiometers, but they turned out to be rotary encoders. Instead of replacing them (would have been a lot simpler) I decided to use an Arduino to make the rotary encoders function like digital potentiometers. This was handy for controlling the high voltage supply, but was overkill for the other variable supplies.

It took some fiddling and internet searching to get some workable code for the encoders, but once I got it, they worked satisfactorily. In order to convert the digital values back to control voltages, I had to send them out to a 32-bit shift register and then run R-2R ladders from those 4 8-bit outputs to get analog values. As the bias voltage needed to be bipolar, I wrote the code to display “0” on the screen when it was outputting 127. That made the control voltage for -10v about 0.5 volts, and the control voltage for +10V about 4.5 volts. So I had to provide my op amp with a gain of 5 and an offset of -2.5 volts.

One of the knobs controls the LCD backlight, which has to be pulse width modulated. I found a cute little voltage-to-duty-cycle circuit on the internet which I used for this purpose. I could have used the Arduino, but had run out of PWM outputs.

The LCD

The LCD is run in 4-bit mode using the standard LCD library for Arduino. This requires 6 control pins, not counting the backlight and contrast circuits. Fortunately, the front panel LCD was a totally standard model and interfacing it to the Arduino was no problem once I found its pinout on the internet. (It doesn’t use the more common single row of 16 pins, but rather the less common double row of 14 pins to one side.)

System noise and a mitigation strategy

Worst case, this system could attempt to switch 4 relays on at the same time. Relay coils are highly inductive loads and these coils draw about 70mA each. This can produce a lot of noise on the 5V line, and was causing my system to oscillate or reset under certain conditions. Though I haven’t taken all possible steps to reduce this problem (such as running the Arduino on an isolated rail), I did create a circuit that detects whenever there is a change in the signals that run the relays, and then applies them in sequence to the relays over several seconds, rather than all at the same time. This does give the system a more sedate personality, though I have not eliminated unwanted resets.

The relays with sequencing circuits are in the upper-left side of the enclosure, as it is pictured. The 4 50-volt power supplies are underneath them.

Making connections

In a complex project, connecting all the sub-assemblies together is a huge issue. I am trying to get better at this by standardizing on .1-inch spaced headers and connectors for most applications. I have a source of cables using these connectors which can carry quite a lot of current. Most such cables are extremely flimsy and only good for signals, not power.

For the main power connections between the supplies and the front panel, I used do-it-yourself high current connectors with locking plastic housings. I used to get these at Radio Shack, but making them myself from parts isn’t too bad.

I also use old-fashioned terminal blocks for higher voltage or higher power connections. These require the use of crimp-on lugs which are not cheap. However, if you know how to use the crimping tool, and fit the wire to the correct lug barrel size, they work very well. I used to use soldered lugs for this purpose, but the terminal block strategy keeps things more modular.

Ending cycle

I spent many hours over a number of weeks on this project, and all to preserve some hardware that I hardly ever use. So it’s time to move on to projects more along my main purpose of electronic art. I’m hoping this write-up will assist me to take my attention off this cycle of action and start some new ones.