This is a library of perfboard and single-sided PCB effect layouts for guitar and bass. I'm not an electrical engineer by any stretch of the imagination, just a DIY'er who likes drawing layouts. It is meant for the hobbyist (so commercial use of any of these layout is not allowed without permission) and as a way to give back to the online DIY community.

Thursday, May 14, 2015

Electro Harmonics Pulsar Tremolo

Here's the original EHX Pulsar trem from the 70s (not to be confused with the modern Stereo Pulsar EHX manufactures today). It features Intensity and Speed controls as well as a switch to go between a hard and soft wavefrom. Original units often suffer from clock bleed from the LFO section. So I've drawn a second layout with mods to try and fix it. The 470Ω resistor above the IC and the 47µ cap below Q1 should be tweaked to find the values that work the best. Pots can be board mounted from the solder-side using right angle PCB pots.





9 comments:

  1. i like the sound it produces in this diy pedal but there's a heartbeat when you're not playing it.. i tweaked it last night and nothing happen. is there any way of eliminating that noise?

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    1. Which version did you use? The stock one or the modded one? The modded one is supposed to get rid of that clock bleed.

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    2. i used your version but it didnt get rid the bleeding.. =(

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  2. Hi man, What you think that sound better, this tremolo or the EA tremolo? Thanks

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    1. I'd probably got with the EA as this one can have some ticking issues. Consider the Heart Throb trem too. One of my favorites.

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  3. No pude solucionar el latido...

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    1. Utilice el circuito sin mod y salio andando!!!

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  4. Today i built the mod one, in my case there is a interesting issue, i had to invert the TL071 to got the effect. TL072 works at the first time when following the scheme and sounds better!
    Here the mods that i did: Cap 470 ohm changed by > 560 ohm, Q2 and Q3 > 2N3904
    Thanks a lot!

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