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Soft Bypass w/o micro-controller

Started by madbean, July 13, 2017, 10:56:26 PM

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madbean

I was watching some youTube videos and came across this:



(his channel is great, BTW)

Anyway, it got me thinking of how to adopt his idea for pedal bypass. Turns out it is very easy! Hence, soft bypass switching using only a few transistors. It doesn't work perfectly (can get a a false trigger now and then) but it's reasonable enough. Plus, it will toggle on and off rapidly if you hold the footswtich down...I call that a feature! Anyway, I've only bread-boarded this so far but I do have a little PCB designed for the Etcher's Paradise so look for that soon after I get a chance to test it some more. Or, try bread-boarding it yourself!

A note: his schematic has a little error in it (1M and 47k resistor values are swapped) which I have corrected on my schem drawing of the bypass.


Boba7

Interesting and fun to watch, thanks for sharing!

I think you should read about Mictester's relay circuit, looks quite similar, though simpler: http://www.freestompboxes.org/viewtopic.php?f=13&t=13295

I built the 1st version of it, using a simple latching switch (a dpdt cause I needed the other pole to switch something else, but a simple latching spdt would work), it works flawlessly. There's a version using a momentary switch later in the topic.

nzCdog

A most entertaining vid.   :)
mictesters one looks cool too!

Freppo

#3
Cool. Thanks for sharing Brian. :)
Fun channel, but I can't stand that overly excited acting  :P

Anyone else has some tips for other nerdy electronic channels?
I'm a fan of the EEV blog and the Ben Heck show.

I believe that you can improve on your design a bit and remove one transistor (Q4) if you exchange Q2 to a NPN (2N3904), emitter to ground, R2 to collector. Then you can drive the relay switching directly from Q2 collector (going negative side of the coil, positive side to vcc, just as Q4 is set up now). That way you can remove R7 and R8 aswell. :)

I also suggest using 12V DC relays insted (and skipping the 5v regular). Most work perfectly with 9 volts aswell, since the switch threshold is usually around 6v (half of 12).

culturejam

Quote from: Freppo on July 18, 2017, 07:28:54 PM
Anyone else has some tips for other nerdy electronic channels?

AfroTechMods. 

I love watching the videos from aVe, which are not electronics but rather more about power tool, milling, metalwork, welding, etc. But the guy cracks me up so hard. His accent is great. NSFW, by the way (unless you have headphones). He apparently sells stuff on Etsy as well: https://www.etsy.com/listing/519921651/welders-ruler?ref=shop_home_active_2
Partner and Product Developer at Function f(x).
My Personal Site with Effects Projects

somnif

Quote from: Freppo on July 18, 2017, 07:28:54 PM

Anyone else has some tips for other nerdy electronic channels?


Big Clive: https://www.youtube.com/user/bigclivedotcom/videos and/or http://www.bigclive.com/

Scottish dude doing reviews/teardowns of various cheap electronics, with schematic explanations of how/why they could be better, plus assorted how-to's and cool stuff