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Buchla 144 dual square wave oscillator DIY
MUFF WIGGLER Forum Index -> Music Tech DIY Goto page Previous  1, 2 [all]
Author Buchla 144 dual square wave oscillator DIY
Peake
For some reason the 4916/3906 in the position nearest the IT122 can be faulty and prevent oscillation. Try swapping that out. If you run into further problems PM me and I'll give you my address and I'll take a look at it.

The matched pair where the IT122 sits should be matched for voltage but even very mis-matched parts should not prevent oscillation. You've got 2N3391A in that one position on both oscillators? And you checked the saw out on the dead osc?
moogboy010
Yes,I have the 3391A in both positions'!The other thing that I was thinking is I don't have the pots' to FM and AM,hooked-up.That pot produces a ground for the input of those areas',so maybe the oscillator needs' those grounds',for a complete circuit?Just a thought?
I will look at the 4916/3906 and see what I find!Thanks for the reply and help!
Update;For those who are wondering,I got the 144 to work a while back!I stupidly added the second-trace to the (Dual transistors') and can confirm that this does' not work!(Peakes') board is right.Dumbest mistake that I have ever made and I have made a few,over the years'! very frustrating
Peake
I'll take it you have a pot wired to +15 and ground, to the Freq input...don't worry about the AM and FM pots. The trimmer closest to the FM inputs sets the initial frequency but I'm not sure it'd go so low as to make the maximum on the middle pot, sub-sonic. Try that first trimmer as well.
pre55ure
Maybe try a 2n5460 where the u147 is in the original circuit.
In the 158's I have built I have had about a 90% success rate with 2n5460's and only about a 20% (or lower) success rate with other jfets.
Peake
Odd, I had no problem with 2N5020 (although they're expensive). Wow, those 5460 are only $1 at Mouser, much less than the other options.
moogboy010
I will try a 2N5460 and see if that solves' the problem.Appreciate the help!
moogboy010
moogboy010
Peake
Mmmm, dual 110 gates smile

Did you get the 144 to work? Are you adding a VC comparator for PWM?
moogboy010
HI Peake.This is a "Terrence Thomas" build,from his book,from years' ago,that is very similar to a Buchla,but has a 2N2646 saw-relaxation osc. and a TL071-schmitt trigger(Square-wave,with a 2N2222,for pulse modulation.The book calls' for a 741,which does' not work for crap,with the poor slew-rate and overall bad performance. It is a really quirky oscillator .It needs' some tweaking,to get everything to work.The pot values' don't go through the full turn,when manually tuning the pulse and the 100K-manual pitch tuners' do a linear sweep,where all of the notes' are crowded,in the treble range.I tried some log pots',but they didn't seem to help.Maybe some reverse log would do it?Anyway,it is what it is.Ha!I have not changed-out the FETs' on the 144 board,yet.Maybe today I can get back to it,I hope.I was very happy with the Art-Work,that you supplied,thru your blog,for the dual #110!It worked the first time I powered it up!!!! we're not worthy I wish you had Art-Work for a "dual Envelope Generator".I looked at the hex-generator,but I am trying to stay somewhat original,with 15 volt supply.I would love to see a schematic of the "Sharp-Cutoff Filter",but apparently,that is another ghost schematic?Again,thanks' for the help,as I very much appreciate it! thumbs up
Peake
If you get tired of poking at the 144 you can ship it to me and I'll take a look, anytime.

There is no schematic out there for the 191 but folks like Djangosfire have put some 292 PCBs behind the front panel and made it work...the 180 dual envelope doesn't use +24V but I don't have a layout for it, perhaps Pre55ure might chime in? Glad you're enjoying the 110s!
pre55ure
moogboy010 wrote:
I wish you had Art-Work for a "dual Envelope Generator".I looked at the hex-generator,but I am trying to stay somewhat original,with 15 volt supply.I would love to see a schematic of the "Sharp-Cutoff Filter",but apparently,that is another ghost schematic?Again,thanks' for the help,as I very much appreciate it! thumbs up


I have an Illustrator file for the 180 EG Panel that I would be happy to share. It might require a little editing as it was based off of some boards that I did for myself and might not be *exactly* Buchla dimensions as far as pot spacing etc... but it's pretty close. Just PM me if you want it.

I don't have an etchable layout but it's not a terribly complex circuit. I did a layout for it (on pcb's) and can confirm that it works as expected.

Also - Peake did the front panel for me and it looks great. w00t
moogboy010
Hi Peake and pre55ure.Thanks' for all of your help and assistance in building these modules'!!! we're not worthy I did 'proto-build' the Dual 180 and assembled it.I'm fairly sure Peake has seen it?was a heck of a job,but it works' very well! I still want to build an original 158A generator.I have the art-work of Peakes',on "press and peel",I just need to burn it.I have all of the parts' in a bag,waiting to go! I also have the art-work ready for Peakes' 156 module.Have just built several of the Fluxmonkeys' boards',all working!YAY! cool So things' are moving along.Lots' of tweaking and once in a while I commit a really stupid mistake!Trying to be careful and take my time.I find things' work the first time that I power them up,If I am very careful in assembly and things' don't go as well,when I get in a manic hurry!
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