Search found 46 matches

by galmar
30 Dec 2014, 15:11
Forum: Ready-To-Build Effect Projects
Topic: A Switching Scheme
Replies: 245
Views: 20505

Re: A Switching Scheme

Hello people, I built the very first circuit (post 1) using a Zettler AZ850P1-5 bistable relay, and it works fine! But it fails to fulfill the number (4) of its advantages. That is, if I suddenly remove the power jack, the relay fails to go true bypass. I assume that the pedal power filter caps are ...
by galmar
03 Jun 2014, 22:32
Forum: Debugging
Topic: big muff voltage doesn't seem right...
Replies: 7
Views: 4334

Re: big muff voltage doesn't seem right...

I did a small approximation above (that does not alter the conclusion), so I will post the detailed calculation for clarity: For Q1: Ic = (current through 12k) - (current through 470k) current through 12k = (9.48-6.75)/(12k) = 227.5 uA current through 470k = (6.75-0.63)/(470k) = 13 uA Ic = 227.5 - 1...
by galmar
03 Jun 2014, 17:50
Forum: Debugging
Topic: big muff voltage doesn't seem right...
Replies: 7
Views: 4334

Re: big muff voltage doesn't seem right...

I did a quick check on the numbers that you posted, and they seem to justify my claim: that your transistors have very low hfe, and they shouldn't. For Q1: Ic = (9.48-6.75)/(12k) = 227.5 uA current through 470k = (6.75-0.63)/(470k) = 13 uA Ib = current through 470k - current through 100k current thr...
by galmar
03 Jun 2014, 17:33
Forum: Debugging
Topic: big muff voltage doesn't seem right...
Replies: 7
Views: 4334

Re: big muff voltage doesn't seem right...

Sorry, I thought you had posted the link to the software you used! As I said before, the most likely culprit are the transistors. Please measure the transistors you just bought, and see whether they have a high hfe as advertised! For example, I ran a DC simulation using a 2N5088 with an hfe=50 (very...
by galmar
03 Jun 2014, 14:07
Forum: Debugging
Topic: big muff voltage doesn't seem right...
Replies: 7
Views: 4334

Re: big muff voltage doesn't seem right...

First of all, you should give us the theoretical voltages that you refer to, so that we can judge on our own. You should also show the exact schematic that you followed, and your parts list, to see whether something is going on. :) Minor differences are never a problem. Consider the fact that the DC...
by galmar
12 Dec 2013, 22:57
Forum: Vintage Stompbox Corner ( ... - 1975)
Topic: Identify this onboard guitar circuit!
Replies: 8
Views: 4864

Re: Identify this onboard guitar circuit!

Maybe diodes are used to protect the IC from certain voltages. :scratch:
by galmar
29 Nov 2013, 20:12
Forum: Stompbox Builder's FAQs & How To's
Topic: wire
Replies: 6
Views: 5959

Re: wire

lolbou wrote:Pre-tin the wires before inserting them in the hole : problem solved. If that 0.8mm hole is too narrow, make it a 1.0 or 1.2 mm hole...:wink:
You bet I do! :)

It is still annoying, though! Solid core needs no such things. :secret:
by galmar
29 Nov 2013, 10:49
Forum: Stompbox Builder's FAQs & How To's
Topic: wire
Replies: 6
Views: 5959

Re: wire

Personally, sometimes I get mad at stranded wire since you have to be really careful not to let any strands go out of the hole, if the hole is close to the wire's diameter. This, of course, is a small nuisance, maybe not a reason not to choose stranded wire. I agree that solid wire is neater, and if...
by galmar
16 Nov 2013, 22:48
Forum: Resistors
Topic: Alpha with only E105 on back?
Replies: 3
Views: 8783

Re: Alpha with only E105 on back?

You can also measure the resistance between legs 1 and 2, for say 5-10 positions of rotation, and then see how it goes. Or just measure it while rotation is 50% - if it measures half the total resistance, it is linear, if it is roughly 10% of the total value it is log. If it is more than 50% it woul...
by galmar
06 Nov 2013, 22:54
Forum: Diodes & LEDs
Topic: how to get 200v 100mA or 1A rectifier bridge using 1n400x?
Replies: 6
Views: 10322

Re: how to get 200v 100mA or 1A rectifier bridge using 1n400

Oops, I didn't notice the schematic. :) Yes, so much reverse voltage isn't necessary. Dirk is spot on about going on the 54XX series. You can again buy a UF5402 as a better replacement if you don't mind the extra cents. By the way, I have a 1N5400 at hand and various 1N400X ones. The 1N400X are the ...
by galmar
06 Nov 2013, 19:13
Forum: Diodes & LEDs
Topic: how to get 200v 100mA or 1A rectifier bridge using 1n400x?
Replies: 6
Views: 10322

Re: how to get 200v 100mA or 1A rectifier bridge using 1n400

No, 1N4003 are rated for 140V of reverse voltage. You should go with 1N4004 at least. I would use anything between 1N4005, 1N4006, 1N4007. If there is no difference in price, I would go with 1N4007.

If you also don't mind getting them or paying a bit more cents for them, go with UF4004-UF4007. :)
by galmar
06 Nov 2013, 19:06
Forum: Resistors
Topic: replacing resistors: 0.6W film with 0.25W carbon
Replies: 3
Views: 8357

Re: replacing resistors: 0.6W film with 0.25W carbon

Carbon film resistors have more inherent hiss noise. A smaller part (usually of lower wattage) will also have more noise too. For the above statement regarding power, your assumptions are correct. Of course, they refer to the worst case scenario - that is, a resistor sees the whole supply across it....
by galmar
05 Nov 2013, 23:43
Forum: Enclosure Finishing
Topic: PT909-style shape aluminium enclosure?
Replies: 4
Views: 9975

Re: PT909-style shape aluminium enclosure?

Musikding also carries the Bare Box:

http://www.musikding.de/The-Bare-Box-1_1

Don't know what suits you, where you live. :)
by galmar
15 Oct 2013, 10:18
Forum: Debugging
Topic: Muff problems
Replies: 12
Views: 5897

Re: Muff problems

I assume you mean a DVM. Anyway, this is used to measure voltages, current and resistance. As I said, you have to measure the voltages at each leg of your transistors. So the black tip of your DVM will go to circuit's ground (battery's black) and the red tip to each pin of each transistor. Tell us t...
by galmar
14 Oct 2013, 21:20
Forum: Debugging
Topic: Muff problems
Replies: 12
Views: 5897

Re: Muff problems

Do you have a voltmeter?
by galmar
13 Oct 2013, 18:37
Forum: Stompbox Builder's FAQs & How To's
Topic: Seeed vs Futurlec
Replies: 3
Views: 2860

Re: Seeed vs Futurlec

Thanks! I may just used seeed for dirt cheap or etch everything myself then. :)
by galmar
12 Oct 2013, 10:59
Forum: Stompbox Builder's FAQs & How To's
Topic: Seeed vs Futurlec
Replies: 3
Views: 2860

Seeed vs Futurlec

As anyone tried these two particular pcb manufacturers to compare them? I am interested only in terms of pcb quality . Not quality vs cost, not speed etc. Just that. I would be glad to hear anyone's opinion that has only used only one of them! If someone has also a foto of a pcb made by any of them ...
by galmar
11 Oct 2013, 18:10
Forum: Stompbox Builder's FAQs & How To's
Topic: SHO issues - Beginner alert, help gratefully received
Replies: 19
Views: 10366

Re: SHO issues - Beginner alert, help gratefully received

I would still insist on following one of the 4 options I have previously stated. I think it is completely wrong to use the chassis as your ground. Think about the path that the output signal has to follow . And also read my previous post again. :)
by galmar
11 Oct 2013, 13:44
Forum: Debugging
Topic: Muff problems
Replies: 12
Views: 5897

Re: Muff problems

Well looking at your pictures I don't like your solder work. Almost no joint is shiny or has a pyramid shape. Also, your pots' solder joints don't seem well to me. I don't know, personally I would solder everything again with care, properly. Before you do that, give us some DC voltages. Vc, Vb, Ve D...
by galmar
10 Oct 2013, 11:45
Forum: Stompbox Builder's FAQs & How To's
Topic: SHO issues - Beginner alert, help gratefully received
Replies: 19
Views: 10366

Re: SHO issues - Beginner alert, help gratefully received

Yes, the conversation above was not supposed to imply that you problem is grounding. I just noted all these because your grounding seems odd - but nobody said it will certainly cause hiss. If I see well though, you attach only the hot wire to the output jack, which means that you ground it via the c...