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Monday, 24 December 2012

DOD 280 Compressor

Here we go with another classic optical compressor. Original unit uses VTL5C2, so could get away with using any LDR with 1M dark resistance. So the LDR resistor would be  resistor leads of VTL5C2 and that green LED acts as LED leads of the vactrol. Positive/anode to strip four and negative/cathode to strip one. Haven't built it myself yet..




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45 comments:

  1. NoNE24 December 2012 at 23:01

    A nice addition thanks !
    And merry christmas

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  2. Equinox25 December 2012 at 02:12

    I can get the VT5C2 fairly easy for $5.24/ea. However, i have never used this component and it looks to have multiple leads (2 on one side and 2-3 on the other)! Thee layout shows 2 hookup points. Soo, how do we hook this up?? Thanks in advance and Merry Christmas!

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    1. mirosol25 December 2012 at 07:56

      VTL5C2 has four leaads - 2 for the LED and two for the resistor. The five leaded one is dual resistor one - and that is not VTL5C2. If i recall correctly it is VTL5C2/3 and those are used with one particular red box envelope filter.

      So basically you wouldn't hookup VTL5C2/3 for this one...
      +m

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    2. HGE Contraptions21 July 2013 at 09:22

      mirosol, in theory, a VTL5C3/2 (not VTL5C2/3) with the five leads, can be used to replace the VTL5C2. Comparing them side by side, you just have to ignore number 4 on the VTL5C3/2, and use 3 and 5 right? I'm thinking that this would be better than making an optocoupler.

      here is a comparison http://img692.imageshack.us/img692/769/h34a.png

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    3. HGE Contraptions28 July 2013 at 18:06

      This comment has been removed by the author.

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    4. HGE Contraptions28 July 2013 at 18:06

      Works like a dream ignoring the middle pin on a VTL5C3/2 :D

      Great compressor

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  3. sf30 December 2012 at 18:19

    any particular diode at the 9V input to the IC?

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    1. mirosol30 December 2012 at 22:53

      Knew i forgot something. That's for polarity protection, so 1N5817 or 1N4001 would be perfect.
      +m

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    2. sf1 January 2013 at 00:46

      thanks! figured it wasn't any sort of specialty model

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  4. Madferret14 January 2013 at 15:13

    Right, I've decided that I've got enough dirt pedals and random noise generators for this week so I'm going to start on this as I've not got a compressor and I've never tried the LED/LDR trick. Quick question; is the LED used going to make much of a difference? I've got a bunch of red 5mm, green 3mm and a handful of various ultra bright 3mm; having never tried an optical pedal build I've got nothing to base this on, I can socket the board but since I'll be using heatshrink wrap to cover the LED/LDR I'd really like to try and get this right first time. Any suggestions anyone?

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    1. Ross14 January 2013 at 16:46

      I read somewhere that green non-clears work the best. Whether this is correct, I have no idea.

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    2. mirosol14 January 2013 at 16:46

      Brigthness of the LED affects the LDR quite a bit. Only way to know for sure is to use sockets and try it out. What are your LDRs rated at?
      +m

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    3. Madferret14 January 2013 at 17:59

      I picked up a few to try different values, I think they're all 1M or higher after 1 second dark. Cheers for the help guys. Sockets it is I guess.

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    4. Madferret14 January 2013 at 20:23

      Ok this one's good for tagging. To be honest I've never really been a compressor pedal user, the last time I used one was about 10 years ago, so I may not be the best judge of the quality but it's definitely doing what I understand a compressor to do: makes things louder, warms things up a bit, works as a clean boost.

      I'll experiment with the different LDR/LED combos but I used a green 3mm and it worked first time, all the LDR's I had were unmarked so it's anybody's guess what value it was. Cheers for the advice before guys.

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    5. mirosol14 January 2013 at 21:26

      That's just super. Thank. You!

      I think that the LED/LDR combo will affect the depth, or squishiness. Next time i place order, i'll get some VTL5C2s and build it myself.

      I'll tag it. You rule!
      +m

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  5. Madferret14 January 2013 at 21:45

    Haha, I've had a few days off work because my girlfriend's been ill, a combination of no work and a girlfriend in bed equals plenty of time to indulge the hobby! I just need to squeeze out a delay and a decent tremolo and I might need a breather for a few days

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  6. Findo27 July 2013 at 13:49

    Hi,

    is D2 the LED part of the LDR/LED? if so, which way round does it need to go? If not, what is it? (do you have the schematic for this too? it doesn't quite match the other DOD280 I found online)

    Cheers!

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    1. Unknown27 July 2013 at 14:41


      Yes, it's a part of the vactrol. The ldr goes in either way and if you look closely, the little cut on the led denoting a cathode is facing up. So that's cathode on row one and anode on row four.

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    2. Findo29 July 2013 at 10:31

      super.. thanks!

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    3. mirosol29 July 2013 at 12:08

      LDR/Led pins are noted in the post.
      Schematic is at http://www.tonepad.com/project.asp?id=21
      +m

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  7. Ross29 December 2013 at 16:43

    I finally got around to building one of these. Although I'm happy with my Really Cheap Bass Compressor, the attack time isn't exactly right for fast fingerstyle playing (it's absolutely perfect for slap, however). I changed quite a few values to let more bass in (470n input cap, 100n caps in the peak detector, and 4.7uf on the output). The most important mod I made was changing the 47uf hold cap to 10uf. This one's most likely going to get boxed, but it absolutely needs a 500K rev log pot for the compression control (plus the only 500K pot I have on hand is dodgy)

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  8. Tronc.the.cube18 June 2015 at 11:38

    Nice, I had to sub in some other resistor values but it came up good. Had to make one after I saw the Australian guy doing a pedal demo.

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  9. HGE Contraptions24 February 2016 at 11:29

    Hi good people! I've built this a few times by now with a home rolled optocoupler, and one with an original Vactrol...but I prefer my optocoupler better heh! Works pretty good, I like it, simple, and useful! Here are some links, you also have a sample under the photos:

    http://hgecontraptions.blogspot.ro/2016/02/dod-280-optical-compressor-third-one.html

    http://hgecontraptions.blogspot.ro/2014/09/dod-280-optical-compressor-aother-one.html

    http://hgecontraptions.blogspot.ro/2014/09/dod-280-optical-compressor-my-favorite.html

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  10. Nikolas Faraguna29 May 2016 at 02:09

    built this for my 2nd build ever.
    success!! and sounds great!! good sustain

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    1. Zack G29 May 2016 at 03:27

      Nice! I've built two of these, one for me and one for a friend. It sounds great on bass and guitar.

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  11. JSA Effects29 June 2016 at 16:56

    This is a great compressor IMO. I've never been a fan of compressor pedals as they tend to be too squishy, but i built one for a freind and, after playing around with some of the values, found you can make this really versatile.

    I took the advice somebody had mentioned in the comments about changing the hold cap from 47uf to 10uf and this really speeds up the release time. However, in some cases it was too fast so ended up putting the 10uf cap and a 100uf cap on a DPDT switch to be able to go between 'fast' and 'slow' settings. I also increased the input and output caps to 220nf so it would play nicer with beefy humbuckers and acoustic guitar. Finally I found that blue non-clear LED's worked best for my tastes.

    Word of (possible) warning; I built two of these using the same IC, transistors, and LDR's and they worked great. I then bulk bought 10 of each from a different supplier. The third one I build acted VERY differently; on the original two, with the 'comp' pot at zero you would only get compression if you really laid into the guitar. With the third one, with the 'comp' pot at zero, there was a lot of gain reduction being applied. After a lot of troubleshooting, I found that it needed 100k resistors instead of the 220k resistors that had worked fine the first two times. I'm *guessing* the transistors had a higher gain than the original four I'd bought but haven't measured then yet. Anyway, that's just an FYI if you experience the same thing when building more than one

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  12. Bill24 February 2017 at 08:03

    Kinda confused on the LDR legs. If theres 2 on one end and 2 on the other, do you stuff 2 legs in one hole? Shouldnt there be 2 side by side holes on the board? Sorry if this is a lame question!

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  13. Bill24 February 2017 at 08:07

    This comment has been removed by the author.

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    1. Bill24 February 2017 at 08:08

      Razvan S obviously used a different layout?
      https://hgecontraptions.blogspot.cz/2016/02/dod-280-optical-compressor-third-one.html

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    2. HGE Contraptions16 March 2017 at 11:44

      Hello Bill! I'm not certain what are you saying...It's exactly like in the schematic! Maybe you misinterpret the fact that I put heat shrink tubes on the LED and LDR legs, and it seems like there is something else there. Respect the layout exactly, and it will be ok!

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    3. Bill16 March 2017 at 14:46

      Hey Razvan! I'm looking at your gut shot and you have a 4 legged ldr, the layout above just has 2 legs? Its the layout diagram above thats confusing me.

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    4. Bill16 March 2017 at 14:48

      If I used a VTL5 opto how would I install it in the above layout?

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    5. tinkercreak18 April 2017 at 16:21

      Bill Kasper

      The layout shows the opto circuit assuming you are using and LDR/LED combo. If you are using a vactrol, the LDR is one half of the vactrol, and D2 on the layout is the other half of the vactrol. Check data sheet for orientation. Does that make sense?

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  14. tinkercreak18 April 2017 at 15:09

    This comment has been removed by the author.

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  15. HGE Contraptions27 May 2017 at 07:18

    Did the fourth, with some mods, very nice pedal indeed! Another one will follow, 5th :)) haha

    https://hgecontraptions.blogspot.ro/2017/04/106th-pedal-built-dod-280-modded-custom.html

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  16. neal gardner14 October 2017 at 07:41

    just built (with 10uf/100uf toggle switch. such a perfect, transparent compression!

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  17. Timothy Watkins31 October 2018 at 02:55

    Hey there! Thanks for this awesome website.
    I am having a problem with this one... when I first plug the power in, I see the LED go from bright then slowly dim to off (assuming expected because of the cap in series). But I get no sound from the pedal. I have checked for bridges and cold joints, no luck. Here are the measurements from GND to each pin of the LM358:
    0.00 1----8 8.86
    0.00 2----7 0.00
    2.99 3----6 0.00
    0.00 4----5 4.39

    Clearly something is up because I have V+ and Non-inverting input voltage, but that's it...
    Any ideas for troubleshooting or even tutorials/videos you can point me towards?

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  18. TedS4 December 2019 at 23:11

    so my LDR is 20K..yeah.. all Tayda had. It worked..but with way too much compression and no sweep to the pot....I put a 680K resistor in series and now it is a little better

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  19. Unknown23 November 2020 at 23:16

    Hi, I can't get the Lm358, could I replace it with 4558 or TL072? thanks

    Hola no consigo el Lm358, podria reemplazar por por 4558 o TL072 ?? gracias

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    1. IvIark23 November 2020 at 23:19

      Yes no problem. Any dual channel DIP8 opamp should be fine

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  20. Unknown25 November 2020 at 01:52

    Ok muchas gracias!! lo e armado pero no funciona, seguramente hice algo mal
    OK thank you very much!! I put it together but it doesn't work, surely I did something wrong

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  21. Ricco Seixas24 May 2023 at 00:19

    Work,thank you so much,great sound!!!

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  22. Rafael Matos27 June 2024 at 16:17

    I've built that one and it worked for a while, after a couple of days it have a bad clipping like a broken overdrive. When I touch the compression knob there is a loud hum, any advice?

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    1. Rafael Matos7 July 2024 at 18:49

      Figured it out, it was a cold solder joint

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