Monday, September 26, 2016

410 Discrete Hex AR DIY

Prototype. AR knob spacing as well as feature set may change. In this one prototype you may notice incorrect front panel text.


This is the all-transistor AR envelope from the Buchla 410 Module Cluster.

Modes include switchable Sustain or Transient (one-shot) modes, a X10 switch for very long envelope times (switching between the 1uF timing capacitor and a 10uF). Lamps indicate envelope output level. Not LEDs, so remember that lamps cannot follow the fastest times possible with this device.

Lamp circuitry is not included on this etch but may be assembled on a rectangle of perf board.


The looping/comparator section is from the 212 envelope schematics and is supposed to fire an output pulse when 0.2V is reached. I didn't manage to get this section working but hopefully someone will chime in.

Initiating it would require a dual-section Mode switch, with one side wired to +15V with a diode and a small RC circuit to reduce it to a pulse, to the input.


Ground, +15V, +24V. Small 24V power supplies can be found at surplus stores and at Mouser for not much money.


This is a 100/410 module, which like the black-knobbed early 200 modules, outputs a +15V maximum voltage. The 110 Gates etc. require +15V to sweep their full response range. Using this with later 200 and 200e modules can pose some issues; VCAs will respond strangely. For things such as filter frequency or oscillator frequency, this is not a problem.

It should be possible to mod this circuit to output +10V; see the Modifications section at the end of this post.


Some 200e modules might not output the correct gate signal to fire these circuits. Will have to find out.


The prototype shown was built with 2N3904 and 2N3906 transistors instead of the indicated 2N3565 and 2N4248 and it works just fine.

Per Envelope:

5) 2N3565
3) 2N4248

for a total of

30) 2N3565 and
18) 2N4248.


1) 2R2 1/2W

6) 47r
6) 6M8
6) 1M
6) 220r
6) 22r
24) 47K
12) 22K
12) 3K3


1) 220uF 50V electrolytic

6) 1uF Tantalum
6) 10uF Tantalum


12) 1N457


For both the shown Quad version and for the Hex etch art as well.


Hex version:

410 Hex Env 1b

410 Quad Env Parts



The 1uF timing capacitor may be brought out to a switch selecting between it and say a 10uF for 10X slower rates. 


Friday, September 16, 2016

RIP Don Buchla.

I met Don Buchla at length when he was pitching and arranging the Buchla Lumina Marimba deal with Nearfield Electronics. We chatted for a few minutes at one point; I won't share everything he said but he mentioned playing the piano as a young man and that his family were against it, that he actually snuck out of his house to play piano on some radio show, I believe at night; it's vague now in my memory. I believe he said he used a different name on-air to get away with it. Yes, I got to see him smile. A truly brilliant man, a genius in music electronics combining his unique aesthetic for human interface and the circuitry itself. I cannot begin to describe the depth of impact his vision has upon me and always will. My heart to him and to his family. Sleep in Light.