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Buchla Programmer DIY
MUFF WIGGLER Forum Index -> Buchla, EMS & Serge Goto page 1, 2  Next [all]
Author Buchla Programmer DIY
pickleinn
Just finished (minus one resistor very frustrating ) my favorite CGS/Serge module - the programmer/sequencer. This time I made it in buchla format. I am looking forward to testing this one out in the full case soon - will post video when i get it going.



Isaiah
Looking good!
Did you 3D print the red structure that the push buttons appear to be mounted to?
pickleinn
Isaiah wrote:
Looking good!
Did you 3D print the red structure that the push buttons appear to be mounted to?


Yes - I didnt realize the buchla style buttons need some kind of PCB support seriously, i just don't get it So i just printed up a bracket to hold them in place. Would change a couple of things to make it better, but it works really well as is.
GrantB
Clap Yes, love the CGS Programmer Sequencer
APETECHNOLOGY
super nice! well done!

applause
mestlick
Awesome. I recently got the VV3 Serge panel with 2x 4*4 versions of that module. I've been using it with Buchla modules too.

I really like how the rows add up if you press multiple buttons. Patched to an oscillator, you can get different pitches with different combinations of buttons.
pickleinn
mestlick wrote:
Awesome. I recently got the VV3 Serge panel with 2x 4*4 versions of that module. I've been using it with Buchla modules too.

I really like how the rows add up if you press multiple buttons. Patched to an oscillator, you can get different pitches with different combinations of buttons.


didnt know that trick - will give it a try - really versatile sequencer in my opinion.
APETECHNOLOGY
are there any component changes needed to make the cgs087 work within the Buchla world?
is there a problem with the differences in gate/control voltages?

hmmm.....
pickleinn
APETECHNOLOGY wrote:
are there any component changes needed to make the cgs087 work within the Buchla world?
is there a problem with the differences in gate/control voltages?

hmmm.....


So far so good.....the output is somewhere between zero and 6-7V so works great butmay not open the whole range of a buchla module up to the 10v range.

Input pulses from the buchla world work fine. I haven't tried output pulses as it isn't putting any out yet.......something i still need to debug. Will follow up when I do.
pickleinn
Got a chance to try it. Clocks well by the 281 pulses, and all but one function works well. There is one issue that I suspect is pulse input related. The individual pulse outputs on each channel appear to be too weak to reset the stage when, for example, patching pulse out from 4 into pulse in of 1 for a 4 step sequence.

I can shoot a pulse from the 281 to any stage pulse in and it triggers as it should.

I can shoot any stage pulse out to the 281 and it fires as it should.

But I cannot patch it back to itself to limit the stages. This is regardless of if I use the buttons or the clock up or down inputs.

Any suggestions on how to modify the pulse out bus to be hotter or longer?
GrantB
I've built three of these and they all just work on 12V and 15V. If it's not triggering itself, I'd suspect a construction error or component problem. Your wiring looks correct as far as I can tell from the photo.

What's up with those caps on the stage boards? You've got a huge one for 470p and a tiny one for 22n. Also you've got those Panasonic films for your 10n instead of the small ceramic you're using elsewhere. Sure you didn't reverse that with the 22n? EDIT: looking again, the 10n is consistent with your main board. I'd still take a fresh look at components though.
pickleinn
GrantB wrote:
I've built three of these and they all just work on 12V and 15V. If it's not triggering itself, I'd suspect a construction error or component problem. Your wiring looks correct as far as I can tell from the photo.

What's up with those caps on the stage boards? You've got a huge one for 470p and a tiny one for 22n. Also you've got those Panasonic films for your 10n instead of the small ceramic you're using elsewhere. Sure you didn't reverse that with the 22n? EDIT: looking again, the 10n is consistent with your main board. I'd still take a fresh look at components though.


yeah, i forgot to order some stuff so just used crap laying around my house - I think you are right though, it should be able to self trigger. I will dig into the components again. The nice thing with this one is its really simple/repetitive.
pickleinn
Just thought I would share my troubleshooting progress. I did a visual inspection of all solder joints (found 2 that were very suspect) and measured all resistor values.

I think the solder joints might fix it (will follow up in a couple of days with results).

Most all of the resistor values measured perfect. The ones i found to be off are marked correctly, but are measuring way off - Is this because they are being influenced by the circuit they are soldered to? I am struggling to understand why just a few resistors would not measure their marked values.

GrantB
pickleinn wrote:
Is this because they are being influenced by the circuit they are soldered to?


Yes. For instance, the 220k wiper resistors are in parallel with each other and the pots, connected by the mix busses and ground. It's usually not useful to test resistors in circuit for this reason, and because they are usually not faulty. It's much more likely that a cap, semiconductor, or connection is faulty.
pickleinn
thanks grantB, that is what i assumed.

So I checked every component and all is correct.
I reviewed and re-flowed anything that looked suspect.
I double checked the wiring.

I cant figure it out. all works 100%. Its only problem is that pulse out of a channel doesnt trigger a pulse in of another channel (but it will if i put a 281 in between to amplify the signal).

very frustrating
pickleinn
what if i dropped the value of the 820R on the pulse outputs to something smaller(like 500R)? would that increase the output?
GrantB
what transistors did you use?
batchas
pickleinn wrote:
So I checked every component and all is correct.

Maybe there are some resistors to tweak as it runs on 15V in the Buchla? Maybe...

I remember on mine (running in Serge with 12V) that I did not have the common PULSE OUT ouputing a signal high enough to drive anything (in Serge or wherever else).
I know you are having an issue with the individual outs, but I'm commenting so you know it even happens with all original values that a signal might no be high enough.
As solution I had to increase the value of the concerned resistor.
the bad producer
Mine (running on 12V and with stock parts) outputs a 4.5V pulse on each stage and is working properly. I've just plugged it into my 15V supply and the pulse output now measures 6V, again it works properly like this (ie triggers other stages).
pickleinn
the bad producer wrote:
Mine (running on 12V and with stock parts) outputs a 4.5V pulse on each stage and is working properly. I've just plugged it into my 15V supply and the pulse output now measures 6V, again it works properly like this (ie triggers other stages).


- I am measuring between 3.6 and 3.8V on each individual pulse out.
- I am measuring 4.56V on the CPO output when i hold any stage button.
- AEP is hard for me to measure as it seems to be a trigger (too fast) and i dont have a scope but it is strong enough to trigger the 281. In fact, it is strong enough to trigger each stage as well.


So i tried an experiement with a straight DC source and "triggered" each stage by quickly inserting a banana plug at a set voltage into the each stage trigger ins.
DC Source set at 0-3V it doesnt trigger
DC source set at 3.8V it doesnt trigger
DC source Set at 4.0V it doesnt trigger
DC source Set at 4.1V it doesnt trigger
DC source set at 4.2V it does trigger nanners

So this just confirms my suspicion that the trigger outputs of each stage are too low to trigger the inputs. Not by much (0.6V). How can i increase these outputs?

EDIT - I played a bit and added a 1K resistor in parallel with the 820R on the pulse output of a channel and it brought my outputs up from 3.8 to 4.4V. Can you see any reason not to just make this mod?


Thanks,
Ryan
pickleinn
GrantB wrote:
what transistors did you use?


Not sure, just regular/cheap bc547 and 557.....could thst be a problem? Got them from mouser.

I may have some different ones, is it worth a swap?
GrantB
pickleinn wrote:
GrantB wrote:
what transistors did you use?


Not sure, just regular/cheap bc547 and 557.....could thst be a problem? Got them from mouser.

I may have some different ones, is it worth a swap?


Those transistors are correct. I was thinking you might have the wrong pinout.

At this point, I don't see why not to go with the different resistor if it works.
GrantB
You know what it might be is high voltage drop across your LEDs.
the bad producer
Nice one Grantb! I wonder if that is it?
pickleinn
GrantB wrote:
You know what it might be is high voltage drop across your LEDs.


I actually considered that as they are on the same output. applause
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