Professor Mark Csele

Sparking My Interests

In the beginning there was nothing – as in vacuum (tubes, that is) …

I grew-up in a time where the vacuum tube was king. Transistors existed, but were reasonably rare in commercial appliances. I recall watching TV on a large (20″ tube) Admiral colour set (circa late 1960’s) which used over 30 tubes! When it konked-out, my brother and I would remove every tube in the set, take a shoebox full down to the local Towers store, and Mom would go shopping while we tested tubes for an hour (you could tell it was the 1970’s – a parent leaving two kids alone in a store for an hour !).

Testing tubes was a tedious affair: look-up the number on a large rotating chart, configure the machine for that tube using a series of rotary switches and potentiometers, plug-in the tube, press the button, and HOPE the meter read ‘BAD’ (in which case, problem solved). If the tube showed good, back it went into the shoebox and on to test the next tube. Eventually, you’d find a bad tube, the clerk would retrieve the replacement tube from under the machine.

Our TV was a console model and was housed in a wooden cabinet. A single dial on the front selected channels 2 through 13 – UHF was simply not a thought in those days. Years later, we got UHF as well (there were two UHF channels to watch bringing the total to eight)! To get UHF we had an external converter box which sat on top of the TV … turn on the box, wait a few minutes for the tube to warm-up, turn the TV to channel 3, and tune the UHF station on the dial on the box.

My actual interest in electronics has been there as long as I can remember. Since I was a kid (a little kid: like six) I had a fascination with electrical things – items ranging from extension cords to lamps. It started, I suppose, with Dad building simple flashlights consisting of a bulb and two ‘D’ cells taped to a yardstick. Other things I recall from my childhood include a Crystal Radio built from a design in the Boys Third Book of Radio and Electronics which we got from the local library. I found a drawing Dad made of the actual radio he built on the back of an envelope with a cancellation date of 1969 (Dad typically drew lots of pictures on the back of envelopes) – it consisted of a piece of wood on which an open-vane tuning capacitor from an old tube radio, a 1N34 glass germanium diode from Radio Shack, and a hand-wound coil on a piece of wood dowel was assembled (it was much more crude than the one shown in the pdf, but still effective despite the fact the tuning capacitor was shown on this diagram as being wired incorrectly). Dad had also built a telephone system where he attached two telephones to a board – I don’t even recall if it worked (i.e. as an intercom) but it was a source of fascination nonetheless. My parents fostered my interests and I even had my own workshop from the age of six or seven. A few of the most interesting things my parents bought for my brother and I were a hand-cranked generator and a spark coil, both from Edmund Scientific and seen here in their 1977 spring catalog I recently found:

This hand cranked generator was a surplus unit used for army telephones. When cranked it would generate over 100 V: enough to light a 60W bulb! As well, one could not touch the terminals while cranking without getting a minor shock. 

… and I did say Sparking my interests …

Now here was a toy I had a lot of fun with, a spark coil was similar to that from a Model-T car (albeit a newer version with a plastic case). Dad soldered three large brass bolts onto the unit. When a 6V lantern battery powered the coil it produced sparks between two copper wires 1cm apart. The coil would easily light fluorescent tubes. I can’t count all of the experiments I did with that coil: everything from transmitting energy through the air by using two large tinfoil plates on the coil at one end (and a second set of plates some distance away with a neon lamp between them), sending high voltage through a trail of graphite filings between the two output terminals, lighting candles from the spark, to shocking my brother’s friends who sat in a prewired ‘electric chair’:). The output, although high voltage, was safe enough because the current was quite low – still, the jolt from the coil was quite startling!

And so, my interest in electronics, and science, was fostered and grew. I had torn apart countless old televisions and radios (keeping many of the parts for future projects) and we had accumulated a large box of vacuum tubes. Dad would also buy electronics magazines like ‘Elementary Electronics’ from which I learned about various circuits. Of course, a good part of my interest was started by observing my brother, Michael, who was into electronics at the time. Michael had a “101 projects” electronics kit and had progressed from the standard projects in the kit (like an AM radio transmitter) to building several projects on his own including a light-flasher for roller skating which involved placing several bright lights on the bottom of roller skates attached to a transistorized multivib. circuit.

The late 70’s were a time when electronics, as a hobby, was the “in” thing and learning kits were common. My brother had one of those “1001” project kits in which you wired circuits between components on spring clips – everything from code oscillators to AM radio transmitters. It was a “MyKit 7” as I recall, from the old Consumer’s Distributing store, and it even had an Integrated Circuit. This was the funniest thing, though, since it was a THICK FILM circuit (not exactly what we’d consider an IC today). Components such as resistors and capacitors were fabricated using an applied-paste process onto the inch-square ceramic substrate. Even that was terribly unique since there were no real commercial products employing ICs yet (Computers, sure, but who had ever seen a computer close-up?) … a few years later and chips flooded the market with everything from logic ICs to the ubiquitous 555 timer. You still see electronics kits like this available occasionally, although they are nowadays a ‘specialty’ item (whereas in the 70’s they were available commonly).

For Christmas, well, most kids would look through the wish book …. I’d look through the Radio Shack Catalog :). The few odd parts to the left, taken from the 1976 catalog (from RadioShackCatalogs.Com) show the kind of stuff they offered back then (That site, BTW, is incredible and if you were into electronics during the 1970’s it will surely bring back many memories). I’d frequently ask for either a “surprise kit” or a project kit like a P-Box Kit from Radio Shack. Each kit consisted of a red plastic box with a multitude of holes onto which the enclosed parts could be assembled to build a metronome, a radio, or, in this case, a night light (which I distinctly remember my Uncle Bob buying me one Christmas). I work with photonics now, but even back then found optoelectronics (including CdS photocells, LASCRs, and other devices like phototransistors) interesting and in this case, this kit taught me a lot about the operation of the photocell. The instructions for the night light, pictured here have a copyright date of 1968 “Allied Radio Shack” (this is the first page of the instruction manual which also has a good photo of what the completed project looks like). Some kits worked well (like the metronome and the night light) while others flopped (like the shortwave radio – never did have a knack for RF circuitry, even today) but I learned a heck of a lot by building these including some basic transistor theory (like “apply voltage to the base and the device turns on” – I had no concept of hfe back then) and learning to read schematics, relating symbols to the actual component. One of my other favorites was the One-tube radio kit which used a 1T4 tube and ran from a 22.5V battery (which fits into a C cell holder) and a AA cell for the filament. That one worked well as I remember and I have provided a PDF file showing the detail provided in these kits for the amateur electronics enthusiast. While I was totally solid-state centric (and dismissed people who, for example, said that tubes “sounded better than transistors”), I couldn’t help but be fascinated by tubes especially since I had seen so many tube circuits in old electronics magazines from the 1960’s. For those who loved these P-Box kits check out The P-Box Kits Page.

Aside from kits, Radio Shack also sold components, some individually (like the silicon phototransistor) and others as assortment packs like the transistors shown here. The transistors in the assortment pack were identified by a spot of coloured paint on each: four types were included. I had also bought a package of FETs, as shown here, and used them to build a touch switch … in 1976, to the experimenter, FETs were quite novel.

While it’s hard to find a good electronics surplus store these days (even in the seventies, electronics was already a ‘dying’ hobby), there were still a few stores like Olson Electronics in Buffalo, NY which supplied both surplus and new components. We’d buy a large (they sold it by the pound) surprise kit when we went “over the ditch” as we’d call it. Inside you’d find all kinds of junk including parts, motors, etc.! These provided a wealth of materials for projects.

Of course, many project ideas came from magazines like Elementary Electronics – the cover of the 15th anniversary issue (Nov-Dec 1978) pictured to the right. Really, we (my brother and I) entered into the hobby of electronics near the end of the era … you just don’t find many electronics hobbyists who build projects anymore (nor electronics magazines for that matter). Perhaps electronics just became too complicated with the advent of micro-miniaturization and the necessity of circuit boards for high-speed circuits, or perhaps kids in the next generation just found other stuff like video games to occupy their time.

My brother recently reminded me that the Rocket Computer featured in this issue was one of my projects, not his, as he had trouble getting the counter to work. Indeed, I recall taking to IC’s readily although I also remember a lot of frustration over things like old CMOS chips which were excessively static sensitive and blew with dull regularity. I do remember using a surplus 7-segment display (from a Radio Shack assortment kit of LED displays – RS had a lot of “assortment” packs available with quantities of LEDs, displays, IC’s, and other components) and adding a sound module to sound a siren before firing. Click on the cover image to see a more detailed view of the computer … recognize the background? Very contemporary for 1978. Another project I had built was a touchswitch using a FET. FET transistors were fairly new then (at least to most experimenters) so it was novel. A hand-shaped piece of boxboard covered with aluminum foil served as the touch plate which, when touched, caused an LED to light. 

My favourite electronics magazine at the time was Elementary Electronics. Popular Electronics was good, albeit the projects were too advanced for me at the time, and so EE had many simple projects that were easy to understand and learn how they worked (if not build them). Consider the Nov-Dec 1975 issue. Priced at $1.00, the main construction project of interest to me was a spaceflight computer (Project Spaceflight by Malcolm K. Smith). This analog computer project consisted of four utility boxes with a host of meters and switches (labelled, of course, with the requisite “DYMO” raised-plastic labels). The operator was required to “fly” the spacecraft by activating the rocket motor at appropriate intervals to keep it from crashing, all while watching the speed and height meters. This same simulation was popular in the late 70’s on early home computers. The actual circuit was two integrators (using 741 OP Amps). Switching the rocket motor on produces acceleration upwards while “gravity” accelerates the spacecraft downwards. Integrating acceleration produces a speed signal (displayed on an analog meter). Integrating again results in height, displayed on a second meter). The goal being to land the spacecraft gently (i.e. at near zero velocity) at the height of zero (i.e. when landing).

I never did build that project, but reading through the article provided a description of how OP-Amps work (including how a split-supply worked) which would prove useful later when I started using these chips in various projects.

It was a timely article – the Apollo missions to the moon had just ended a few years earlier and the Space Shuttle was already announced – and so space flight was still an “in” thing. The author, BTW, was apparently quite a “Trekkie” since he makes many references to Star Trek episodes in the article (which even includes several photos from the series).

Another article I found useful in this issue was An old flash from a new IC which featured circuits using what was at the time my favourite IC, the LM3909 flasher. Other notable features in this issue were a plethora of advertisements for CB’s (23 channel, of course, and one from Johnson for a CB featuring a very new LED meter display for signal strength), the required ad for Radio Shack P-Box kits (priced at $7.95 each and including both the one-tube radio and the night light), an Edmund Scientific ad, and a host of terribly cheesy classified ads in the back for everything from “Make $1000 a month stuffing envelopes” to “Beautiful girls wanting American men”. 

As well as Elementary Electronics (which provided a good start), I also regularly read Electronics Today International (commonly available in Canada) and later Popular Electronics.

Other projects I remember building?

How about a remote telephone ringer which used a neon light as an opto-isolator and rang a loud bell when the phone rang. Or a timer (555 based) which connected to a pocket calculator – you’d key in “1+1” and the circuit pressed “=” once per second causing the calculator to increment and count in seconds (This was a project from Elementary Electronics magazine, Sept-Oct 1976, entitled “Mark-time counter”). Or a guitar booster which was cloned from a commercial unit (a small single-transistor amplifier, basically). Or a full-blown synthesizer which featured modules like a VCO, sine-wave shaper, and ADSR. This large project, pictured to the right, consisted of a wood frame which held a number of modules built into aluminum panels. It was the size of a commercial keyboard.

And in general, I built a bunch of little circuits on the breadboard using chips like the 4017 decimal counter, the LM3914 bargraph display, and the LM3909 flasher IC: things like handheld games using LEDs.

By the age of twelve I was constructing multi-channel colour organs using SCRs and audio transformers. Most of the basic designs were found in books like ‘101 electronic projects’ which gave a schematic and a basic one-paragraph description … the ‘hobbyist’ approach to learning electronics (which I still believe is the best way to learn!). One of my favorite plans was this Single Channel Colour Organ. I expanded that basic design, with the help of an article in a 1967 Electronics Experimenter’s book (The “Musette” color organ by Don Lancaster originally in Popular Electronics July 1966), into a five-channel colour organ. Five audio transformers were used to drive five SCRs. R/C filter circuits on the secondaries were used to separate the frequencies for each channel – these proved to be the achilles heel of the design since they are sensitive to amplitude – and years later I would discover how active (OP-Amp) filters work which would have allowed vast improvement (And nowadays, when I built one again in 2010 for my daughter, I just threw a DSP chip at it).

At the time, my brother had entered the local science fair, building a light communication system and, following in his footsteps as all little brothers strive to do, I built a project for grade 7 entitled ‘A GSR monitor’. My (faulty) hypothesis attempted to prove that plants had nerves. The project wasn’t spectacular but it was a start and involved some interesting electronics like a homebuilt strip-chart recorder. The basic unit itself was nothing more than a homebuilt power supply and a sensitive microammeter in series. Most parts came from a load of old electronics provided by a cousin in Buffalo, NY, who was disposing of a garage-full of old parts and books (electronics and ham radio). On a visit there, my parents picked-up a load of books and parts including things like indicator lamps – those nice little coloured jewels so popular in the 50’s and 60’s – and like any techie I incorporated lots of indicator lamps in my projects.

Oh yes, and where did I ever come up with the idea of a GSR monitor ?. Back to the old Edmund Scientific catalog … in 1977 one the interesting things was to study biofeedback and such. Remember, this was the 70’s, just after the drug-tainted 60’s. Disco was IN, Psychedelic was IN, even mirror balls were IN (Yes, I found them in that catalog as well!). Could you tell this was the 70’s from the caption ‘Tune in to your tulips’?. And the colour organ I mentioned? They were big in the 70’s as well. See for yourself in this advertisement in the Edmund Scientific catalog. People think of the 60’s as ‘psychedelic’ but the 70’s were almost as strange!