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 Forum index » DIY Hardware and Software
Buchla 230 Triple Envelope Follower
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beautyofdecay_



Joined: Aug 14, 2009
Posts: 38
Location: Netherlands

PostPosted: Tue Nov 02, 2010 1:32 pm    Post subject: BOM updated Reply with quote  Mark this post and the followings unread

I found 2 errors in the BOM.
You will need 6 4.7k resistors (not 3) and you will only need 2 ferrite beads instead of 6.

I uploaded the new BOM which you can download in my previous post.
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camelneck



Joined: Sep 27, 2008
Posts: 68
Location: KY (USA)

PostPosted: Fri Sep 07, 2012 9:53 pm    Post subject: Reply with quote  Mark this post and the followings unread

TekniK wrote:
Done! did take me more time as expexted,If some one try it ,feedback is welcome.

Pdf contains PCB + parts implementation.


I still see an error in the PCB layout. I believe that this module will work correctly once this error has been corrected.

When I first glanced at the 230 schematic I noticed two things that were a bit confusing:
#1) The right side of R6 connects only to the left side of R10.
It appears that Teknik has since fixed this problem on his revised layout.
#2) C2 connects to pin 1 of the op amp (not pin 2).

While the first issue was resolved correctly in Teknik's latest PCB layout, issue #2 has not been resolved correctly. C2 has been mistakenly connected to pin 2 of the op amp instead of pin 1.

If we assume that the schematic is correct (and I believe it is), C2 HAS to be connected to pin 1 of the op amp. Otherwise, the schematic would be wrong because it would imply that both inputs of the op amp (pins 1 & 2) are shorted together and there is no way the circuit would work properly if this were the case. (Teknik must have seen this problem and thought that the schematic was wrong, because the inputs aren't shorted on his layout.)

Unfortunately, I have not etched the PCB yet. Thus, I can't VERIFY that this correction will make the PCB 100% functional. However, for anybody who has already etched Teknik's revised version of this PCB and mounted the components on it, it is a very simple matter to correct this problem. Just follow these 2 simple steps:
1) Unsolder and lift the leg of C2 (100pF) that is closest to pin 2 of the 4136 IC.
2) Solder this now lifted leg of C2 (100pF) to pin 1 of the 4136 IC.
ALTERNATIVE: It may be easier to solder the lifted leg of C2 to diode D1, which is located right beside C2. Make sure that you solder the lifted leg of C2 to the leg of the diode that is connected to pin 1 of the 4136 IC. (This should be the leg of the diode that is closest to the lifted leg of C2.)

To fix the PCB layout,
1) Reroute the trace from pin 2 of the 4136 so it runs between the two solder pads for C2. By doing so, this trace will no longer be connected to one of C2's solder pads. (In fact, ths solder pad (for C2) will now be unconnected.)
2) Run a trace from pin 1 of the 4136 to the unconnected solder pad of C2. (This is the pad that pin 2 of the 4136 was previously connected to.)
3) Make sure that you repeat these same changes for the other 2 circuits on the PCB.

I honestly believe that fixing this problem will make this module functional because I didn't find any other problems.
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n.d



Joined: Dec 15, 2011
Posts: 20
Location: Argentina

PostPosted: Sat Dec 29, 2012 9:51 pm    Post subject: Reply with quote  Mark this post and the followings unread

So, camelneck, did you make it work?
Anyone?
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oneoff



Joined: Nov 23, 2008
Posts: 42

PostPosted: Sun Feb 24, 2013 8:01 pm    Post subject: Reply with quote  Mark this post and the followings unread

Quote:
Hi TekniK,

Unfortunately I did not find a picture of the traces side of the PCB (yet).

maybe this will help to move forward ...
the back side of the PCB from an auction

http://3.bp.blogspot.com/-2Zt5uWFdUdo/UP301pXFy7I/AAAAAAAGdJ8/s7IqxXPeM_g/s1600/%2524%2528KGrHqV%252C%2521q0FCz%252BHCwQ5BQ%252BdU4z%2529Vw%257E%257E60_3.JPG
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Starspawn



Joined: Jun 14, 2013
Posts: 24
Location: Oslo

PostPosted: Tue Jul 30, 2013 10:16 am    Post subject: Reply with quote  Mark this post and the followings unread

Great, good luck to all, Im watching this and will build once the hard work is done Wink
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camelneck



Joined: Sep 27, 2008
Posts: 68
Location: KY (USA)

PostPosted: Mon Aug 26, 2013 6:28 pm    Post subject: Reply with quote  Mark this post and the followings unread

Some Good News.

After postponing this project several times, I finally got some spare time last week and decided to bite the bullet. After finding and correcting at least 12 mistakes (4 mistakes on each of the 3 sections), I etched my own PCB using Press N' Peel Blue. (The biggest problems with Teknik's layout involved the supply power to the op amps. They were being powered from the trim pot meaning they were powered by less than +/- 1V instead of +/- 15V. There was also some grounding issues that had to be corrected. I also moved the leg of the 1oopf capacitor from pin 2 to pin 1 of the IC.))

It had been awhile since I last etched my own PCB, but the final product turned out perfect with all traces intact. Unfortunately, I only had 1 5K trim pot and just enough of the 1.0uf and 4.7uF capacitors to complete 1 of the 3 Envelope Followers. (So only 1 of the 3 envelope followers on the PCB has been built and tested so far.)

The good news is, the first of the three envelope followers, which was completed and tested this weekend, seems to be working just fine. However, it may be 2 to 5 weeks before I receive the remaining parts, make my front panel, complete all the wiring, and give the entire module a thorough testing. However, I have toned out all the traces on the remaining two envelope followers and since they are identical to the one that is working, I don't expect any problems (certainly nothing major.)

While I await the remaining parts that I need, I am going to make a front panel which will probably be like one of those that RSFC was selling some time ago. Once I receive the parts (4 capacitors and 2 trim pots), I will solder them on the PCB, complete the wiring, and test the entire module. Once I'm confident everything is working properly, I'll upload the revised PCB layout as well as a jumper map. (The parts layout created by Teknik can be used for the revised layout.)

A few days before I started working on this project, I sent Technik an email requesting a higher quality jpg file as well as permission to modify the file that he made. However, it has been over a week since I sent that email and I've not received a response.

PETTY ISSUES

I wish that some of the pads were a bit bigger. I enlarged some of the more critical pads, but I didn't have the time to enlarge them all especially since I was having to do this in Paint Shop Pro. This may not be an issue for people who are using drill bits smaller than 1/32". The only drill bit that I had at that time was a 1/32 of an inch which is a bit larger than the ones I have used in the past. Thus, I managed to chew up a few pads during the drilling process. However, since the traces were fairly wide, I was able to solder to the trace when no pad was available and this worked out fine.

Another issue was the power connector. I made an error in judgement and "assumed" that the +15V, gnd, and -15V pins were spaced at 0.156" apart and I left them "as is" since I planned to use a MTA-156 header which MOTM PCBs have.. However, the pins turned out to be spaced 0.2" apart. I modified a 6 pin MTA-100 header (removing every other pin) and soldered it here. However, the simplest and best solution is to just solder the power wires directly to the PCB instead of using a header.

This PCB has a lot of jumpers--14 total. I had to add several more jumpers to the PCB in addition to those that Teknik had already added. I will iupload a jumper placement drawing when I upload the revised layout.

Last edited by camelneck on Tue Aug 27, 2013 1:09 pm; edited 2 times in total
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fluxmonkey



Joined: Jun 24, 2005
Posts: 695
Location: cleve

PostPosted: Tue Aug 27, 2013 8:01 am    Post subject: Reply with quote  Mark this post and the followings unread

so, is the original schemo correct? (some of them have deliberate errors...)

Posted Image, might have been reduced in size. Click Image to view fullscreen.

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camelneck



Joined: Sep 27, 2008
Posts: 68
Location: KY (USA)

PostPosted: Tue Aug 27, 2013 1:14 pm    Post subject: Reply with quote  Mark this post and the followings unread

fluxmonkey wrote:
so, is the original schemo correct? (some of them have deliberate errors...)

Posted Image, might have been reduced in size. Click Image to view fullscreen.


Yes, the schematic is correct. As for the unlabeled capacitor, I used a 100pf capacitor.
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memorygardens



Joined: Mar 06, 2013
Posts: 4
Location: Cleveland

PostPosted: Mon Jan 06, 2014 8:18 pm    Post subject: Reply with quote  Mark this post and the followings unread

any hope on a revised layout? I want this to be my first diy buchla project......
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