Boss Bypass Momentary Hack?

thehallofshields · January 19, 2018, 02:58:27 AM

Hey guys, a lot of digital pedals using micro-controllers for bypass offer toggle switches to go between Momentary / Latching modes.

If anyone has ideas on how to achieve that with a Boss type bypass, I'll gladly breadboard them and try them out.

duck_arse · January 19, 2018, 09:05:03 AM

break the connection between R41//C23 and C26//C27. connect instead R41//C27 to R48//C27, and that will only switch while you hold down. if your initial on is the wrong one, swap the connection over to the other transistor base.

thehallofshields · January 19, 2018, 04:26:50 PM

Quote from: duck_arse on January 19, 2018, 09:05:03 AM
break the connection between R41//C23 and C26//C27. connect instead R41//C27 to R48//C27, and that will only switch while you hold down.

Awesome. I drew up what I think you are describing.

Used a DPDT On/On/On to get: Normally Bypassed | Latching | Normally Engaged
What do you think? Will it work? Overkill?

duck_arse · January 20, 2018, 08:35:14 AM

interesting - are you made of switches? I would have just used a single pole double throw - do you have a use for normally engaged?

and yes, that seems pretty much what I was thinking, have you tried it on the BB?

thehallofshields · January 20, 2018, 01:03:55 PM

Quote from: duck_arse on January 20, 2018, 08:35:14 AM
interesting - are you made of switches? I would have just used a single pole double throw - do you have a use for normally engaged?

No I don't have a use for normally engaged; it's just theory crafting. If I were to build it I'd go with an SPDT and skip that option. I'd probably skip the Zener Diode too.

blackieNYC · January 21, 2018, 10:32:40 AM

Guys, this is great. I had been recently exploring ways of doing this - mom switch, latching switch, and switch between. And the (slow) JFET switch seems to be the best way of silently, or perhaps smoothly, switching an audio path while audio is actually passing.

thehallofshields · January 21, 2018, 03:23:32 PM

Quote from: blackieNYC on January 21, 2018, 10:32:40 AM
Guys, this is great. I had been recently exploring ways of doing this - mom switch, latching switch, and switch between. And the (slow) JFET switch seems to be the best way of silently, or perhaps smoothly, switching an audio path while audio is actually passing.

Absolutely. Noiseless, soft-touch switching with some flexibility.
I could see it being very useful for Oct-Up, Tremolo, Noise Effects etc.

The only problem is we're looking at 8 Transistors to implement it.

-- 2 BJT for the Flipflop
-- 1 BJT for the LED
-- 3 JFET for the Bypass
-- 2 BJT for the Buffers

blackieNYC · January 23, 2018, 10:49:24 PM

Built this, using BC182s then BC547s. (Just like the lower drawing-just lighting the LED) I have it working in normal Boss mode, alternating on, off, with each button press.
It misses a switch about 1 out of 15 closures. I've used all the values in the first drawing. What might I need to do?
In momentary-effect-insert-mode, I'm getting no momentary response - one output is On, one is Off. They will respond to the first button press, then they are done. Is it possible we have a flaw?
"..connect instead R41//C27..." Do you mean C27 here, or just C23?
Thanks

duck_arse · January 24, 2018, 09:06:00 AM

yes, I think I do. R41/R42/C23 provide the pulse or the pull-up. connected to C26 and C27, they [should] toggle, connected to either R48/C27 OR R47/C26, they will pull-up normally open, pull down when pressed. turns out, no I don't.

ahhh - I see now - there is one thing I missed to say - remove R48, and switch to that base for momentary. sorry about that.

thehallofshields · January 26, 2018, 03:16:37 PM

I'll gladly redraw the schem if you guys get it to work.

blackieNYC · January 26, 2018, 03:27:49 PM

R48 - cool, thanks.

I also need to figure out why mine is working "almost consistently". I'll post some voltages.

thehallofshields · January 26, 2018, 06:21:57 PM

Just curious, what type of switch are you using?

blackieNYC · January 26, 2018, 08:52:01 PM

Usually I must admit I'm touching a wires together, but for this I happen to have a very nice momentary stomp.
Still need to sit back down to the breadboard, make duck's change, and record some voltages. I must be out of tolerance with a part or my transistors are a poor substitute.

duck_arse · January 27, 2018, 08:37:35 AM

I don't want to mention the value changes on the circuit I built all that time ago, because they are only minor, one up and one down-like. I've always found the flip-flops, in every version I've tried, from all the manufs, to be a little not-100% on test on BB.

blackieNYC · January 27, 2018, 12:17:11 PM

Quote from: duck_arse on January 27, 2018, 08:37:35 AM
I don't want to mention the value changes on the circuit I built all that time ago, because they are only minor, one up and one down-like. I've always found the flip-flops, in every version I've tried, from all the manufs, to be a little not-100% on test on BB.

As in, prone to noise/errors until you put in inside an enclosure?

Momentary function is perfect now - remove R48 and attach the switch circuit there instead of where the caps meet. I can also remove R47, leave them both out, and get momentary insert on the base of Q7, and momentary removal on Q8.

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Boss Bypass Momentary Hack?