Huge strip/matrix/bread board used by DIY organbuilder

[gtc]

This (circa 1970) DIY switching matrix, comprising some 1,500 transistors, is constructed on the largest piece of strip/matrix/bread board that I have ever seen. It measures 4 ft x 3 ft.

I was a trainee tech at that time assembling prototype circuits on 3 in by 4 in boards. I have no idea where the builder obtained such a large piece of drilled epoxy. Anyone ever seen such a thing?

[Admin]

Looks like two panels split vertically down the center to me. But yeah. Why? Its size would make mounting components and wiring them awkward indeed. Impressively neat, though.

[Coenraads]

Of about the same vintage (mid 1970s) is the multiplex system I built for my ten rank home pipe organ. The demultiplexers, one for each rank, were built on 18" by 6" strips of Veroboard. Copper strips on the back ran horizontally and the components plus any needed jumpers ran vertically. By making suitable cuts in the copper strips, it was remarkably easy to build circuits of any complexity. I used many square feet of Veroboard not only for the demultiplexers but also the multiplexer, the combination action and the computer-organ interface. That is how things were done in those days.


On the left are four demultiplexers mounted in a wooden frame for the four ranks of pipes on the left. The ones for the pipes on the right are yet to be built. The chips are 74174 six bit latches: two per octave.

I'm mightily impressed, however, by the massively parallel wiring for the organ you show in the picture you shared. Nothing wrong with going that route and it looks very well done. But going with smaller individual panels would certainly have made the job much easier.

[AllenAnalog]

Seems like the 70s were a time for big circuit boards. Here are all of the boards I took out of my Saville analog organ when I gutted the console.

[gtc]

Looks like two panels split vertically down the center to me. But yeah. Why? Its size would make mounting components and wiring them awkward indeed. Impressively neat, though.

Yes, a closer shot shows the join and also the copper bus bars running vertically like a DIY Veroboard.

BTW: the cabinet is the remains of an Everett Orgatron. These boards contain the key and pedal/stop switching matrix. To the left of the console sits a chamber holding 5 ranks of pipes configured as an extension organ.

[gtc]

Seems like the 70s were a time for big circuit boards. Here are all of the boards I took out of my Saville analog organ when I gutted the console.

Thanks AA. Great picture!

I'm thinking it's more a slight hangover from the 1960s. In 1971 I was a trainee tech making prototype devices for our engineers using 7400 series logic chips on filing card size Veroboards, and 7400 type chips is what I would have used instead of 1,500 transistors on a massive backplane, but I guess the guy who designed used what he knew from his own experience.

In production those Veroboard prototypes became PCBs with edge connectors that sat within slots that were all from the British ISEP range, then popular with said engineers: https://www.srs-products.co.uk/the-isep-range/.