PYE Compressor/Limiter Thread *boards shipping* BOM up!

Corrected, updated and re-posted! Im sure there will be more...

Did you get a chance to verify my findings on the switch board?

The meter feeds back into itself like that?  Hmmmm

That seems to be the way it is wired, Get your ohm meter out, it should take thirty seconds to bounce off the schematic. Let me know if you find anything.

You have INPUT POT labeled twice!

haha. Good ol copy and paste.....

I'll fix it, but the schematic is laid out pretty much like the board. All the headers are in the approximate location and orientation as on the board.

Hey guys. Haven't been here in a while, had some things come up which took me away from this awesome compressor.
Kind of strange to see all these issues etc going on? ...and abe's no longer around?

I don't believe it. Seems like too nice of a guy.  ;D

Def still full tilt on this project...in a bit, when things get smoothed out. Nice to see you guys are ironing out some of these details, for us slower types.

I see it more that the community is coming together to get something working.  Abe has been quite busy lately and doesn't have much time to hit the boards lately.  And yes, Abe is an awesome guy, but sometimes the more important things take up our time.

Hi
Does anybody have any suggestions as to where is the best place to take the audio signal from  if I want to display audio input level on a LED VU meter?

/Taz

tazwolf said:

Hi
Does anybody have any suggestions as to where is the best place to take the audio signal from  if I want to display audio input level on a LED VU meter?

/Taz

Click to expand...

I guess it would be on the input transformer's output (or at the input leg of C3; or at the input leg of the IN potentiometer). But you'd need to add a driver of some sort depending on what kind of meter you're using.

Now I have a question!

PN3640 is obsolete almost everywhere I searched!
I can get MMBT3640 which is from the same product line but it's SOT-23 package. I could solder wires on it's legs and connect it on the board but it would look ugly and may be prone to break after some time.
On some place I found info that MPS3640 is supposed to be replacement but it's values on datasheet differ a bit. Can this be used? (this one is available in a local shop and it's cheapest!)



Luka

Hmmm. I got my 3640s from mouser.

sr1200 said:

Abe has been quite busy lately and doesn't have much time to hit the boards lately.  And yes, Abe is an awesome guy, but sometimes the more important things take up our time.

Click to expand...

Fair enough, but I would expect for at least the first round of building the guy that developed the project be present to iron out things.

That includes providing an up to date schematic which takes about 5 minutes time. Instead we had to put one together by reverse engineering!

I would suggest that this build thread be one of Abe's priorities until things are sorted. Lot's of questions remain.

Mark

mdainsd said:

Hmmm. I got my 3640s from mouser.

Click to expand...

Yeah well, seem like only Mouser carries them!
Someplace I read that it was discontinued in 2012.

My problem is that in my country Mouser charges too much for shipping. It's not affordable to pay 10 times the price for it!

Could someone check the links to datasheets I put in my previous post and cross check if MPS3640 would work.  ;D
I did cross check and noticed MPS3640 has positive current values, while PN3640 has negative. (in fact it's just the same numbers but without minus sign so I'm hesitant to think it's maybe ok). It could be it's a different switching transistor, but why would it be listed as replacement... uhh... im confused... 

Shot,

The MPS3640 data sheet I looked at has "negative values" listed. Its a PNP switching transistor, which is what is called for. What I do see for both types is that the pinout  (when looking at it with the flat facing you is) from left to right e,b,c.. Be sure to double check before installing. The pinouts on the board are c,b,e for that transistor. Abe used the square pad at each transistor site for the collector (or maybe more correctly "pin 1" as the majority of the transistors used have the collector on pin 1), and I added those to my schematic..

Besides the meter issue, what other questions remain?  I'll see if i can get them answered.

mdainsd said:

Shot,

The MPS3640 data sheet I looked at has "negative values" listed. Its a PNP switching transistor, which is what is called for. What I do see for both types is that the pinout  (when looking at it with the flat facing you is) from left to right e,b,c.. Be sure to double check before installing. The pinouts on the board are c,b,e for that transistor. Abe used the square pad at each transistor site for the collector (or maybe more correctly "pin 1" as the majority of the transistors used have the collector on pin 1), and I added those to my schematic..

Click to expand...

Yeah, I also cross checked those two datasheets and MPS3640 seems to be biased for positive current while PN3640 is for negative. Beside that, all the values are exactly the same. All but one - they differ in Rise Time. Maybe there's some other transistor similar to MPS3640 but in the negative current range that will do.

Bruno2000 was kind enough to promise to send me couple of PN3640's.  Thumbs up for him!! So I'll go with suggested part.
But there may be other builders with no access to Mouser, or Mouser stops carrying them since they are already discontinued, so it would be cool to have an alternative for this switching transistor.
I'm still tempted to put sockets in the TR11 position and try different transistors beside the suggested one. That may happen when I finish my unit. But now it's far from being finished since I'm waiting for transformers and some other parts. I ordered them just recently.

sr1200 said:

Besides the meter issue, what other questions remain?  I'll see if i can get them answered.

Click to expand...

In context with meter issue, try to ask what would it take to be able to use regular vu meter!
I have a lot of regular (mostly cheap chinese) vu meters that look cool and I'd like to use a couple. I guess that would require adjusting value of R65 and R67. But if there's anything specific on that...

And also, what would be the difference if R38 is fitted with 12mH inductor compared to 100R resistor.
Should I just forget the inductor and go with the resistor? I get the impression most of you guys did that without problems...

Hii
Do any of the transistors need to be matched?

/Taz

@ Taz, not to my knowledge.  My unit works fine, i didn't match anything.

@shot, we're barely getting questions regarding the circuit as is, don't think we're going to get an answer about a possible mod, but I'll ask.  As far as the difference goes, just socket the part and try both and see what sounds better.  I did the 2 inductors on mine.

Shot.

"And also, what would be the difference if R38 is fitted with 12mH inductor compared to 100R resistor.
Should I just forget the inductor and go with the resistor? I get the impression most of you guys did that without problems..."

It is a L/C network vrs a R/C network for the -12V regulator used to power the SC. It wont affect anything, use the resistor.