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Buchla 100 system diy build
MUFF WIGGLER Forum Index -> Music Tech DIY Goto page Previous  1, 2, 3, 4, 5, 6, 7, 8, 9, 10  Next [all]
Author Buchla 100 system diy build
bluedonkey
Hey all,

I found a great way fo making panels cheap. Using a service like this

https://uk.whitewall.com/photo-lab/alu-dibond/direct-printing-on-alumi nium-backing

Anything white will just be aluminium. I made a Serge panel this way. I cant remember how much it was, but I think around the £10 mark.

Dibond is a sandwich of aluminium plastic and aluminium. Its a bit softer than normal ally, BUT the graphics are good and very durable.



aonghus
A question regarding power:

Do you have to build your own power supply for these 100 series modules, or is there a modern one you can use?
Peake
Depending upon the number of modules you want, and which ones you want, a 1A to 1.5A or larger +15V supply is mandatory. Some 3rd party module adaptations can add features requiring a -15V rail, and some modules such as the 190 dual reverb require a +24V rail. It's perfectly fine to add a 500ma or larger linear or wall wart +24V supply to a +15V supply and wire them into the distro. More amperage is better, and it's good to have reserves.

I've completed a pair of 100 Series module which use +24V and I've used pin 10 on the EDAC for it so the owner can add a +24V line into their distro on pin 10 and add other +24V modules later as they please.
moogboy010
Buchla-clone model 158A (Saw/Sine-Generator)- build.This is peakes' Ebolatone-board!
The etch turned-out really nice!The matched pair of transistors',at the front of board are (TIS-97s');The (emitter and collector)are reversed,compared with a pair of (2N3904s)'!
Peake
Good etch!

I haven't updated my page yet but use the original 1K5 resistors in the sine shaper, not a pair of trimpots, but DO use a trimpot in place of the 470r resistor to ground just before the sine shaper. Pre55ure says this is the place to trim for a good sine wave.
moogboy010
O.K.,I will try that!The oscillator is working in range with a(U147) in the osc.section .
I have a fairly pure-tone,with a (2N4339) and the trims' tuned?Have to look at it on my scope?All is good,so far! It's peanut butter jelly time!
moogboy010
Here is a pic,so far.(10K-pot) needs' cleaned.I will replace this with a new-pot!
thumbs up Picture file
moogboy010
Everything is working well.Have not decided about the sine-wave?
APETECHNOLOGY
Peake wrote:
Good etch!

I haven't updated my page yet but use the original 1K5 resistors in the sine shaper, not a pair of trimpots, but DO use a trimpot in place of the 470r resistor to ground just before the sine shaper. Pre55ure says this is the place to trim for a good sine wave.


Peake, its the 3.3k next to the 470 ohm i remember from a while back...
but changing the 1k5's to trimmers has no bearing on the performance?
i already have them installed, i guess i will find out tomorrow ,

thanks for the info!
APETECHNOLOGY
and nice work moogboy010!
crushing it!
we're not worthy
Peake
Do I keep getting that wrong? Sorry. The 1K5s definitely influence performance but Pre55ure said the other resistor is much more important.
moogboy010
Thanks' for the compliment,Apetechnology!
I will leave the (1K) trim-pots' in place,for (Sine-Symmetry),but will change the 3.3K
resistor to a (5K,or higher) trim-pot.Makes' sense.You are controlling the bias,thus gain of that transistor,lowering(signal-input) to the (Sine-Shaper). Should reduce distortion of (sine-wave-form). thumbs up
Thanks' for the revision,Pre55ure and Apetechnology! applause
Jarno
Coming back to the 144 (or other projects that need a P-chan FET), Peake, did you try 2N3820 for the P-chan FET instead of U147?
It seems to be pretty similar to 2N5020, where 2N5460 has higher Idss.

By the way, on the board for the 144 I changed everything to 3904 and 3906 footprint. Will order boards next week.
moogboy010
I made some (J175s') work,in the model#144. Unfortunately The U147(Very difficult to find,if at all) is a natural! All (4) of mine worked in Peakes' 144 board! hmmm.....
Btw; From what I have been able to learn,I think the gain of the matched pair have as much to do with which (Jfet )will work,as anything.Might take a lower(hfe-matched-pair),for a different transistor.As I stated before,I used (TIS97s'),with a gain around (hfe=505).A set of (2N3904s' ),with lower(hfe) might work better,for other(P-channel-jfets')? I had a wider range of tuning control,with the(1K trim-pots')and the (U147),using the (TIS97-matched-pair).
Jarno
Interesting, so not just the jfet but rather the combination. Will try out, I have changed the board to 3904 for the matched pair, lets see if i can get some different fets and try out.
moogboy010
Sounds' good,Jarno,
Let us know your results'?
Btw,I have an original-NOS(MD708B/dual-transistor),that I picked-up in some stuff from a "Ham Radio Fest",several years' ago!I have tested the (hfe) on both sides,under different temperature conditions' and this dual-can stays around (hfe170)! I used that as my (target-value) when matching transistor pairs'.The (MD708B) was probably used in most (Pre-CBS) Buchlas'? The (IT-122) tends' to be a good-bit higher(hfe),usually (hfe-450) and up?
Not-saying that (bias-resistors') don't have a lot to do with the oscillation and performance of the (jfet),but I think that the driver-transistors'(Dual-Pair)have a large-role.
Best of luck hmmm.....
hydn
This is really incredible work you're doing!
Peake
The IT122 are well-matched for both voltage and gain. The MD708B is very sloppy in comparison.

I have not used anything to substitute but 5020 and J175.
APETECHNOLOGY
so i fired up a couple 158's the wave shapes were ass shaped, the one in the picture is actually not that bad,
i replaced the 3.3k with a 5k trimmer
and i was able to adjust out the "ass"!
thank you Pre55ure for the tip!
the new question is, how much should the saw look like a saw?
i did not take a pic of my saw, my 252e is giving the 158 a work out and it sounds nice!
thank you Peake for the hard work!
moogboy010
Beautiful job,Apetechnology.
Nice,clean board! Sine-wave looks' very-symmetrical!
Congrats' on a quality build! Rockin' Banana!
Peake
Loving everyone's builds! Thanks for confirming the best way to get a sine in the 158! That's some 2nd harmonic right there. Trim out all the ass!

cygmu
Peake wrote:
Loving everyone's builds! Thanks for confirming the best way to get a sine in the 158! That's some 2nd harmonic right there. Trim out all the ass!


Yes, this is very interesting and quite possibly pertinent to other JFET sine shaper sections.

I guess the thing being trimmed is the peak-to-peak level of the triangle going in?
moogboy010
HI Peake,
Love the GIF,Hilarious!
lol Here are some (Dinosaur-screen-shots') of the wave-forms' from the 158A and 144.
A little blurred.Got to change the exposure time on damn-camera! angry
Peake
cygmu wrote:
Peake wrote:
Loving everyone's builds! Thanks for confirming the best way to get a sine in the 158! That's some 2nd harmonic right there. Trim out all the ass!


Yes, this is very interesting and quite possibly pertinent to other JFET sine shaper sections.

I guess the thing being trimmed is the peak-to-peak level of the triangle going in?


I believe that's what Pre55ure said, makes sense.
moogboy010
Here are some (Dino-scope)-shots' of the (140 pulse generator),with various pulse-widths'Picture filePicture filePicture filePicture filePicture file
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