Digital Electronics – Page 3

Developed Fully Mitre Transformer Core Shear Controller

One of a number of controllers that Vansco developed for Micro Tool and Machine, my thesis partner Danny Lew and I took on the development of the Fully Mitre Core Shear Controller as our undergraduate thesis. We built upon the existing software and main controller board, but had to modify the programming to accommodate left/right/angle stops on the head rotation, distance measurement on the material progression, and control of the material movement, shear rotation and closure, and punch activation.

I did a PCB layout (double sided tape on mylar – that was some time ago!) for the I/O board – incorporating multiple options, including some that we weren’t able to use – several of the boards were manufactured. I kept one as a momento.

We were just wrapping up the project when the blizzard of final exams hit, so the my manager Lorne Repas did a chunk of the finishing work. Overall, I was very proud of the result!

Like many Micro Tool and Machine controllers, we hoped that there would be repeat orders, but to my knowledge, we only built the one. I’m pretty sure Micro Tool would have liked repeat orders too, but it just seemed that we were always doing one-offs. That’s life.

Developed Electric Heater Load Shedder Sequencer for Lion Industries

Vansco Electronics was in bay 3 of the Industrial Technology Centre, at Lagimodiere and Fermor. Lion Industries, a similarly sized mechanical product manufacturer, was next door in bay 2.

With the energy shortage in the recent past, and ongoing issues with the cost of oil, the Canadian government sponsored the “off oil” program which would subsidize homeowners to switch from oil heat to electric heat. Lion Industries manufactured an electric furnace that would retrofit into the ductwork, leaving the oil furnace intact.

The Load Shedder Sequencer would intercept the thermostat request for heat, and instead of letting the oil furnace start, would turn on the furnace’s blower only, and engage the electric furnace elements, one at a time, in sequence.

The challenge was that the home would not have had its electrical service panel updated, so we put a small current transformer (CT) on the incoming service power, measured the overall current consumption, and would shed, or turn off, elements to keep the total current under the rating for the panel. We had little plug-in modules that would “program” the system for the capacity of the panel in the house.

The concept was that if power was being used by another device in the home, that would generate heat which would help to heat the home. For instance, a stove or oven.

If, after a long time (15 minutes), the thermostat was still asking for heat, the electric furnace would shut down and engage the old-fashioned oil furnace.

I developed the entire design, end-to-end, of course with the oversight of the other, more experienced staff. It was my first encounter with thyristors – in particular, TO-202 triacs. I had considerable difficulty with them apparently engaging when they weren’t supposed to – and found out that they were overheating and becoming overly sensitive to stray gate currents. What an experience!

Debug prototypes of Enercorp AI-1 Air Infiltrometer

The IAMC (Industrial Applications of Microelectronics Centre) had developed a product called the Air Infiltrometer 1 for Enercorp. The AI-1 could automatically measure the leakage of a home by replacing one of the doors with a large fan, and measuring the pressure drop across it as the fan was sped up. Enercorp had been manufacturing manual units that used TI-59 calculators, but the AI-1 made it all automatic.

The AI-1 mechanicals and PCBs were developed by Vansco. The main board was based on the Motorola MC6802. The PCBs came back and were built up, but everyone else was busy working on getting the Conviron CMP3000 going, so there was nobody to do the initial debug.

Although at that point, I had no idea what a microprocessor was or how it worked, I was given the MC6800 manual and Ed’s dusty old Krause Industries Micro Maniac development system, and asked to give it a go. I put the development system together, dusted off the tape recorder, loaded up the development tape, and got the AI-1 up and running in 2 days.

Experimentation with TTL and Making a Television Transmitter

I built 8 digit frequency counter using Vector wire-wrap technology, but my front end design had poor sensitivity.

Then, for the science fair, I designed & built a simple TV transmitter, with horizontal & vertical retrace counters and end-of-frame equalization generator. I obtained a still-functioning Plumbicon camera tube from a local TV station, and proceeded to build a camera frame around it, using deflection coils from an old television set, and a home-brew high voltage power supply using a tube-type TV’s power transformer. I was unable to get the camera to function, but I was able to generate a raster that I could sync a black-and-white television to!

Later, I developed “TV typewriter” using TTL logic, hand-drew schematic on large sheets of paper, but once I was introduced to the PC, that fell by the wayside.