Advice for Psych-Tone project

[theehman]

For no reason whatsoever I've been working on a board layout for the Psych-Tone which is an old synthesizer /sequencer found in an old electronics magazine.  The main issues I'm having is the 6 bank interlock switches and the 24vdc/3.3vdc power supply.  I was wondering if there were any modern methods of replacing those.  I'd like to run it off an adapter if possible.

[tonyharker]

Have you seen this? http://www.till.com/articles/psychtone/

[theehman]

Yeah, but I want to have a physical version.

[PRR]

> Psych-Tone which is an old synthesizer /sequencer found in an old electronics magazine.

Where is this old electronics magazine?

[PRR]

That's switching insanity. The gang-switches are now rare, rotary switches now have different leg spacings (won't fit the PCB), and a LOT of wiring is by-hand. (Ah, you do your own layout.)

I doubt the actual switches matter; DPDT and 1P12T switches are still available. It wants interlock but I don't think anything smokes if not interlocked......

24VAC and 6VAC transformers are still around.

The UJT (not PUT) may be a hunt. And known-good RTL chips will be a real pain to source; TTL can work but with what mods? (page 49 gives clues)

The metalwork in Fig 11 is non-trivial.

Fig 8 S5 is drawn wrong. Better get the next 5 months and check errata.

[Mark Hammer]

> Psych-Tone which is an old synthesizer /sequencer found in an old electronics magazine.

Where is this old electronics magazine?

Here you go:  https://worldradiohistory.com/Archive-Poptronics/70s/1971/Poptronics-1971-02.pdf

Ignore the "Poptronics" title.  They're using the final publication name for all or most of the issues of Popular Electronics, going back a ways.

[bluebunny]

You can find those radio buttons, although they're not common.  I found some on the Bay (China, natch) and used them in my Blue Shift build:

[theehman]

I had a couple of the switch banks but forgot where I bought them.  A little more searching on ebay turned up a seller with a few still in stock so I bought those.    I have plenty of the 2N4871 FETs and most of the BJTs and mosfets as well as the MC791P.  I probably have some of the other RTL chips around here somewhere.  I guess now that I've found switch banks I won't need to replace the switching.  Probably going to power it with a 24VDC adapter with a tap off to a 3.3v regulated circuit for the RTL.

[PRR]

....Probably going to power it with a 24VDC adapter with a tap off to a 3.3v regulated circuit for the RTL.

Do your homework first. Lancaster gives an example of not-much-RTL-logic sucking 228mA:
https://archive.org/details/RTL_Resistor-Transistor_Logic_Cookbook/page/n25/mode/2up
Take that from a 24V source, you drop 24-3.6= 20.4V at 0.228A is 4.66 WATTS. He rounds-up to 0.25A, 5.1 Watts. A TO220 regulator will do this, with a not-small hunk of heatsink.