Wednesday, 7 May 2014

BYOC Tremolo

Request.  The stomp is wired in an unusual way so I have shown exactly how to do it.  The reason for this is that during bypass the input to the effect is grounded and the emitter of the LFO transistor is disconnected from ground, and so stops the LFO continuing to cycle during bypass.  This is a really good method because you can be sure that no LFO bleed-through will be heard as people have experienced with other effects with oscillators.  The indicator LED connections are shown and this will pulse in sync with the oscillator, and because the bypass method stops the oscillator when off, this means the LED will be off too.

Info about the original BYOC project and board:

The tremolo has become one of b.y.o.c.'s most popular kits through word of mouth. And with good reason....the difficulty of the build is low, it's simple to use, and it just sounds good. This kit is based on the EA(Electronics Austrailia) Tremolo. It's a great vintage sounding trem like you would find on an old Blackface Fender Amp. The amplitude modulation is done with transistors, so unlike most opto-coupler based trems, you don't get an "on/off" sound on slower speed settings and there is much less current draw. It's also a lot easier to build. And the LED status light blinks in time with the speed. 






80 comments:

  1. do we need to match transistors?

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    1. I think I may just have everything for this build except the C100k

      Would love to give it a go when I get some time

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  2. Finished soldering. No signal on or off. LED is not blinking while engaged just lit up. Will have a thougher look tomorrow, anyone else having a go at this?

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    1. I've just been over it all again and I'm pretty confident the layout matches the schematic. Check the suggestions in the Fault Finding page from the menu above and if you don't have any luck then post the voltages here to see what clues it gives us.

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    2. I've pulled apart my board (light stopped completely) and started again. New board has no light too. I followed your trouble shooting advice, all seems well. Here's some pictures and voltages. Also wanted to say I've built the 4 knob keely comp and sparkle drive from this place and think its an awesome resource full of helpful chat.
      Q1
      D-6.8
      S-4.49
      G-3.25
      Q2
      C-6.8
      B-1.42
      E- .94
      Q3
      D-3
      S- .2
      G- .94
      Q4
      C-6.9
      B-5.56
      E-6.48

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    3. Can you post the pics. Have you wired up the switch, and if so is it working ok in bypass?

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    4. Having trouble working out uploading photos, is there a trick? Signal when not engaged. Switch wired up. Am getting the dreaded ticking though.

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    5. Upload them to one of the free sites like tinypic and then just post the link.
      The thing that confuses me straight away is that you're showing 6.48 on the emitter of Q4, but when the pedal is on that is grounded at lug 8 of the switch via that Sw7 wire from the board which goes to lug 7. If that isn't 0 volts then the oscillator won't be working and so no effect so that is something you definitely need to check.

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  3. Nice layout lvlark, btw how do you say your name?? hehe
    thnk you
    vince

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  4. I love this site so much! Thanks to the guys that make this site possible. I would like to see where i can donate to for the site? Can someone direct me pls. vince83687 at gmail
    cheers
    vince

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  5. http://tinypic.com/a/368u9/1
    hope that works

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    1. Well your cuts look right but it's hard to tell anything else. I think the important thing is trying to work out why there is voltage on the emitter of Q4. When the effect is in the on position, use you multimeter to check the voltage on the Sw7 wire, then at pin 7 of the switch, then pin 8 of the stomp and tell me what readings you get.

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    2. Switch 7 wire: 2.666
      Pin 7 of switch: 2.672
      Pin 8 of stomp: 2.667
      Hope there's a clue here.

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    3. If pin 8 isn't 0 volts then it isn't grounded. How have you connected ground to the board and everything else?

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  6. cause i havent boxed up yet, the board ground, pin 8 and the input/output sockets are all dog clipped together to the negative terminal of the battery clip.

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    1. Well if that is the case the voltage couldn't be 2.[something] volts. Also you have 6.48V on Q4 emitter, but 2.672V at pin 7 which is connected to the emitter by a solid copper wire, so something is definitely wrong with your connections.

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    2. On the byoc site the jumper wires on the switch are connected differently. Is that anything? I'm going over and over this thing, maybe I should do the echoplex preamp just to have a win? :)

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    3. Have you got a link to the pic? I added the extra wire to ground the input during bypass, but the real question that needs answering is why Q4 emitter isn't grounding. Lug 8 is connected to ground by a solid wire and isn't showing 0V, so the switch doesn't affect that. If ground isn't 0V then there is something wrong with the grounding of the effect.

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  7. Hi Mark, I have the problem with this tremolo also. I have 0V on the emiter of Q4 , but have a very weak signal ( volume pot max) without tremolo. I have no switch yet, SW2 green wire is an input, volume 2 - output, SW7 connected to the ground. I've compare your layout with the schematic on BYOC website and everything is correct. I've done almost 20 effect and 1st time have such problem. By the way - thx for this blog !

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  8. heres the switch picture. http://i62.tinypic.com/2wg50s9.jpg

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  9. So, I only have a C500K pot, how can I make it 100k (or close)? What resistor value should I use and across which lugs? Thanks for the help!

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  10. take 125K , solder between 1 and 3 lug .

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  11. Anyone built this yet? The demos sound fabulous!

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    1. A couple have built it and had problems, but I've been over it and I'm confident it matches the schematic. Maybe the schematic has an error on it to stop people doing their own layouts :o)

      I'll investigate when I get chance and maybe trace the PCB to see if it matches the scheme in the PDF.

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  12. great, Mark, I'm waiting for your investigation. I've found this schematic in X file :), but it matches your layout
    http://byocelectronics.com/schematics/tremolo.jpg

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  13. Anyone had a win with this? I'd like to try again but don't have any trouble shooting skills.

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  14. Not having any luck with this one. With power, and pedal disengaged, the clean signal comes through, but the led is lighting up very dimly. When I engage it, the light pulses in time with the rate, but not getting any sound at all. I've checked and rechecked for bridges, grounds, bad joints, crossed wires, and proper component orientation and such, but no dice. Might have to sleep on this one for a while.

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  15. i strongly believe that there is a problem with the schematic.
    as i was drinking my coffee i was looking at this. and from that schem on byoc, i can't see why q3 and q4 are for.
    from q2 we have a connection to output, and then the signal from q3 and 4 goes always to ground.
    i'm not an expert, but it doesn't make sense to me. except if it changes the "ground situation" somehow witch is also something i've never saw again.
    i'm trying to find how we could change the switch wirings so that this part of the board will do "something" but it's my birthday and i'm having a party in a couple of hours so... good luck! maybe i'll try it the next days.
    if i've said something stupid here, i'll take it back!

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    1. Q3 & Q4 are the LFO (low frequency oscillator) that provides the pulse for the amplitude modulation circuit.
      +m

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    2. I know I said I'd do it and haven't yet, but when I get a chance I'll trace out the board and see if I can see any variation from the schematic. I'm pretty confident that the layout matches the schematic, so something is amiss somewhere.

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  16. so i've said something stupid here miro...sorry!
    mark i've checked the layout and it's perfect.
    but i just couldn't understand (with just "mechanical thoughts") why there must be a switch in that part of the circuit from emitter of q4 and from input.
    it doesn't make sense to me when the effect is off, but i'm sure i should read about that lfo thing...hope someone will solve this cause it's a really nice tremolo..

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    1. The emitter of Q4 makes no connection in the bypassed state, and so when you turn the effect on it also grounds the emitter which turns the LFO on and as a result also starts the indication LED pulsing in sync with the set speed. It's a very good idea actually because in most circuits the LFO continues cycling in the background when the effect is bypassed, and then you can get ticking noise bleeding through the supply or ground connection. With this that sort of noise would be impossible because the bypassed state also stops the LFO

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  17. great man!thanks! that makes sense now...you should write a book someday..!!!!

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  18. Q2 Emitter resistor is labeled 100k on BYOC schematic but 180 on BYOC PCB. Diode is 1n4001 and connected differently also. Please confirm. i'll try this later

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    1. The diode is fine, I just connected in series instead of parallel so you don't have to worry about it exploding (as I do with most of these circuits), but the 180R will obviously make a huge difference so great spot on that one. Let us know how you get on with that change.

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    2. No luck so far, have no audio. led is working
      I'm using 1uf tantalum and electro caps and maybe thats the prob. I have positive facing the led and Q4 Base. the other 1uf i tried to flip but doesn't work anyway. Maybe i should get all 3 caps Polyester?

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    3. Tantalums do not work at all the polarity is reversed. That could explain a part of it. But all those three 1µ caps are at the LFO side, so you should still be getting the signal through. If the LED is blinking, then the LFO is working. Do you get signal at Q2 base and collector?
      +m

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    4. Looking at the schematic, all three 1µ caps should have have their positive leads down and negative leads up in case tantalums or aluminum electrolytics are used.
      +m

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    5. Yeah its working ;)
      Thanks mirosol! my vol3 wire was in the wrong row, noticed when tried to trace the signal;)
      I looked at a couple of different variations on this tremolo circuit and this one is a winner! Sounds awesome too! Good for boost if you need it. i would like to have more volume drop with depth, but it's very good as is. Thanks Mark for this site - Amazing!

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    6. So i followed mirosol advice on caps and changed 100k resistor after Q2 emitter (below D1) to 180Ohm. worked for me!

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    7. Great to hear it's working!
      I'm not tagging it yet, in case Mark wants to swap the resistor values on Q2 emitter...
      +m

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    8. Sorry guys I totally missed this, I will update the layout and tag it. Thanks for verifying Paulo

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    9. It doesn't work for me too, any update ?
      thx for this blog :)

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  19. The updated layout works perfectly for me. Thanks guys!

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  20. Got it working. Sounds great. Any ideas as to why in by-pass mode does the LED glow dimly? Any thoughts as to how to resolved? Only a very minor issue. Thanks again for this great site!

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  21. i would think its supposed to glow dimly in bypass mode. its does still pulse correct?

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  22. This comment has been removed by the author.

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    1. I have dry signal in bypass. silence when switch engaged. LED solid on in either mode. volt readings are:
      Q1:
      D: 9.12
      S: 5.69
      G: 4.26
      Q2
      C: 9.06
      B: 1.88
      E: 1.47
      Q3
      C: 0
      B: 0
      E: .29
      Q4:
      C: .06
      B: .05
      E: 0

      Any ideas?

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    2. had c5 oriented wrong. Now I have steady dim LED on bypass with dry sound, oscillating LED on effect with no sound. Values of Q! and Q2 are the same. Q3 and Q4 are:

      Q3
      C 0
      B 0
      E oscillating 0-3.0

      Q4
      C osc 0-5.0
      B .5
      E 0

      please help

      thx

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  23. Built this today. Works great.
    I couldn't find 2n5457, so I bought 2n5458. I've also missed 3PDT, so instead I used DPDT and put Sw7 and ground to the separate on-on switch. This way, LED is always blinking. And if I'd have 3PDT, I could use one more LED just for the effect state (on/off).
    I'm not sure if I can connect Sw7 directly to ground. Maybe IvIark or Mirosol could clear this moment.
    That would be cool to have 2 LEDs, one for state and one for rate.

    I have some low level noise when effect is on, kind of police siren sound. Maybe it's because there is no enclosure now, and the effect just lays on the floor.

    Many thanks! I've already built two pedals (BM Ram's Head and Green Russian BM). All of them works great!

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  24. Bypass signal working with LED off. In effect mode the LED pulses and a there's clean signal that goes up and down with the volume knob, but no tremolo effect in the audio. What should I look for where the signal path meets the effect?

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    1. Hi all, I've got the same issue, what's wrong?

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    2. The transistors were on the wrong way.. So now it works perfectly. Just have the led blinking and always on both mode

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    3. Took me a while to find your question since it's right in the middle of all the old posts.

      Did you follow the 3PDT wiring shown here in the layout? It is different from the normal offboard wiring method because it uses one pole of the switch to kill the LFO. When it kills the LFO the LED should turn off too.

      Sounds like there is an issue with your offboard wiring. If you can't find the issue, post some high res photos in the forum in the Debugging section for help

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    4. Hi Travis,

      I think the problem may be come from the ground? I connected the SW8 to ground via the output jack ground. So do I have to connect SW8 directly to the ground on board?

      I will send picture asap, thanks in advance

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  25. This comment has been removed by the author.

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  26. I just built this and it sounds great. I did have a problem with the rate pot. I put in a 100k(C) for a reverse log and it acted like a 100k(A). i just ended up reversing the legs and it works great. here is a short video of the pedal. https://www.youtube.com/watch?v=DZNgWDG8c3E&feature=youtu.be

    p.s. yes I used a 10mm LED and i love it :)

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    1. Thanks for sharing the vid Paul, sounds and looks great

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    2. You're welcome Mark. I want to say your page has been so beneficial to not only me but countless others. So a big thank you to you as well!

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    3. Built this one yesterday and it sounds really good but it does seem to really depend on where i put it in my pedal chain. I may need to check for a short as it sounds horible on its own.

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    4. hmm, well i had mine at the end of the chain and just recently put it in the beginning since I am running two amps and it seems to sound the same. so there is probably something wrong.

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    5. Cheers Paul, i will work thruogh all the possibilities tomorrow.

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  27. Would J201s work in place of the 2N5457s?

    I don't have any 2N5457s but a bunch of smd J201s.

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    1. I reckon it probably would work? Tbh I don't know the ins and outs of the design, but J201s and 2N5457s are generally interchangeable with minor tonal changes (at least in mu amp circuits etc).

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  28. Just built this and it sounds fantastic. However the Rate control is reversed. The connection directly under LED- should be Rate 1 & 2 and Rate 3 should go to ground with Depth 1.

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    1. Same thing when I did it. Applied your changes and it works as intended. Thanks!

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    2. I can confirm that as well. The Rate control works the other way round, and should be wired differently.

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  29. I'm almost finished with this build and I've run into a strange problem. The effect works as long as the speed setting is between about 10 o'clock and 3 o'clock. If I go to a setting outside this range the effect stops working, (I still get sound and still have full functionality from the level knob, just no trem in audio or LED). Another strange observation: If I set it outside of the 10-3 range, and then set it back it lags for 2-3 seconds befor the effect kicks back in. This is true for the sound and the LED.

    Anybody have any ideas about what I should check? Really appreciate the help and I love this site. Thanks to all for the effort.

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    1. I figured it out.

      I had forgotten to mention that I substituted the 2n5088s with 2n3904s (pretyy important detail, my bad). I went back and tried several other NPN types and found that 2n4401 worked much better. My issues are gone now.

      I am wondering if I could have also used trimmers with the 2n3904s to get around this. I am still pretty new to this so I don't know exactly how that would have gone, does anybody know of any references on how/where to user trimmers when swapping transistors (or any other time they may come in handy really)?

      Maybe I just need to read more about transistors.

      Anyway, I did it, it sounds great, and my first attempt at etching the enclosure went really well. http://imgur.com/Uo1joKF

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    2. I've not built this, but I can't see any reason why 2N3904 should not work, but 2N5088 and 2N4401 work ok. They are roughly eqiuvalent, and along with 2N2222 are commonly swapped around in the same circuits as substitutes. It could be an issue whereby the specific gain of the transistors in this circuit is important, and your 2N4401 were nearer to the required figure than your 2N3904.

      Also bear in mind that it is possible that it has nothing to do with the transistors at all, and it could be you have a cold solder joint somewhere.This can give you that mystifying "works fine until I touch or move something" effect.

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    3. Interesting. I did try the 2n2222 and got similar results to the 2n3904. Also, I doubt it was a cold solder joint because I rigged it up to be able to easily swap and try all my NPN transistors by soldering jumpers to the transistor positions with alligator clips on the other end to attach transistors. The issue with 2n3904 was repeatable, as was the success with the 2n4401.

      Is there any chart or other reference that details the gain of various similar transistors?

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  30. Works perfectly (for those who have problems , let me tell you that I recently discovered while building this, that I had a full batch of 2n5457 that was faulty :| causing the led only to work. I changed it with to a J201). Here is a video! :) and some pics https://forums.rgc.ro/uploads/monthly_01_2016/post-2645-0-57354400-1451988981.jpg https://forums.rgc.ro/uploads/monthly_01_2016/post-2645-0-05670100-1451988981.jpg https://www.youtube.com/watch?v=Oytv5aqqzW4&ab_channel=RazvanS.

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    1. Unfortunately there are an awful lot of fake JFETs on ebay, so you are not alone in having problems with them!

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  31. Could you let me know why the led is blinking on both mode (bypass & effect on)?
    If not the effect sounds really good. Thanks for the layout.

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  32. Hi everyone!
    I tried this one and the chopper trem by Ian Mcdermott, and i have the same "issue" with both. The effect is OK on all points but the depth is very... subtle. When depth knob is at maximum, the tremolo effect is far from what i could see on working clones on YT. I tried several 5088 from fairchild but no luck.
    Any idea? THanks!!

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  33. I'm not having any tremolo effect coming out and the LED lights very very dimly, with no pulse. The boost sounds great though, so I've got signal going all they way though.

    I used 1uF Monolithic Ceramic capacitors, so there was no pos/neg side. Would this cause the problem?

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  34. I got pulsing led with no audio, I tracked all connections ans seems to be all ok, any ideas?

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  35. It works good! Min 1:18 https://www.youtube.com/watch?v=Y-N6OtHT49U

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