First of all, thanks to transmogrifox and Philip Bryant! Without their info this project would not have been possible.
This question comes up a lot. How do I true bypass a BOSS pedal? Answer(s):
- you can't
- you can't stuff a DPDT switch in there
- don't bother putting one in, the buffer is high quality and sounds good
- don't bother putting one in, just build an external TB box with four switches and a jack etc.
- you're an idiot, BOSS pedals rock why would you want to mess one up
Alrighty then! Well, I had an SD-1 lying around so I decided to mod it to "another pedal" specs. "Another pedal" is true bypass, so I figured I'd go whole hog and change the whole thing. SO, here's a pic of a BOSS pedal with true bypass:
(http://img60.exs.cx/img60/6168/SD1.jpg)
I know what you're thinking: HUH? That's just a regular SD-1, it's not true bypass. Well, let's open up the battery hatch and see what's in there, shall we? HMMMM, did CD manage to stuff a DPDT in there?!?!?!!
(http://img54.exs.cx/img54/9445/SD9.jpg)
OH. That was a bit underwhelming. There's no DPDT in there, it's just a regular SD-1. Which isn't true bypass. Well, you're right. That's the stock BOSS switch in there. So I didn't manage to stuff a DPDT in there. But I thought it was a BOSS pedal with true bypass. What did you do to the insides then? OK, here's the last pic:
(http://img54.exs.cx/img54/8692/SD10.jpg)
On the bottom right you can see the small bit of perfboard that houses a latching relay and the associated control circuitry. The relay is a DPDT which is used for TRUE BYPASS. Since it's a single coil, latching type relay, battery drain is minimal (even though I use a power adapter exclusively). Two opamps are used to drive the relay (circuit by transmogrifox - search for "latching relay" and a website with a link will pop up with the schematic). I used the stock BOSS flip flop as a latch to control the relay, so the momentary switch is left in place, as is the stock BOSS indicator LED. The whole thing works beautifully, with a tiny tiny bit of switching noise - nothing you wouldn't experience from a regular 3PDT though.
At first I thought I would rewire the stock BOSS switching FETs to a "Clinton Bypass" (see GEOFEX) since the FETs are already there, and FETs are good at that. When I opened up the pedal there was a lot of room so I thought if I'm going to rewire the damned thing, I might as well get rid of the FETs and go real TB with a relay. It took a bit of shoehorning in - the relay perfboard is a smidge too tall which made the backplate a bit tough to get on.
It would have been MUCH easier to use a 2 coil latching relay, that way you could use the latching relay driver on GEOFEX - but I couldn't find any locally so I went with the single coil. Thanks to transmogrifox for his relay driver circuit, and Philip Bryant for his excellent SD-1 schematic - without it I would have probably went blind figuring out all the connections.
I don't have the time or inclination to post up a full tutorial on this mod (and I don't want to help the commercial modders), but all of the relevant info can be found at the usual places: searching the forum, GEOFEX, Google, etc.
sweet idea. Where'd u get the relay/how much can they be had for?
I got the relay at a local store, cost was $2. You can get them at all the usual places though, Mouser, Digikey, etc. The relay I used was a 5V, single coil latching relay. You'll want to get one that is low profile (5mm or shorter). I used a socket for the relay so it's actually about half as high as it looks.
Nice job!
I like it because you didn't modified the box, so it looks original. And I like to keep the feeling of a Boss pedal even when modified. And you kept it.
Gilles
That's very cool!
Apparently you can true bypass boss pedals. I saw a pic that someone removed the top of a blue 3pdt footswitch and drilled the hole larger where boss one is to fit the footswitch..
I'm not the one who posted the pictures, but after looking that pics I did it to my Boss Delay, removed the top of the switch, sanded for lowering the height...
BTW: You don't need to drill a bigger size hole for the 3pdt !!!
Now my Boss Delay makes "clank" :D when I switch on or off!!!
Works nice, I've been giging with it and it's perfect!!!
Search the archives, now I can't remember all the details, but it's on the archives for sure.
Kleber AG
cd,
Where did you connect your relay into the flip flop circuit? I have a schematic from Phillip, too.
Thanks!
Quote from: syzygycd,
Where did you connect your relay into the flip flop circuit? I have a schematic from Phillip, too.
Thanks!
The flip flop is used as a switch to signal the relay driver to turn on/off.
nice.
I designed a small and simple circuit that can translate the internal BOSS flip-flop collector voltages into pulses (few mS) well suited for drive a two coils latching relay. Basically is a high impedance input buffer, a differentiator and a driver for each coil.
this is the PCB version:
(http://www.thundertomate.com/varios/TB_Boss2.jpg)
(http://www.thundertomate.com/varios/TB_Boss3.jpg)
(http://www.thundertomate.com/varios/TB_Boss4.jpg)
and this is the really small version (some boss pedals don't have too much free space): :lol:
(http://www.thundertomate.com/varios/TB_Boss1.jpg)
VERY nice.
Inspiring.
Fp
Quote from: Robertonice.
I designed a small and simple circuit that can translate the internal BOSS flip-flop collector voltages into pulses (few mS) well suited for drive a two coils latching relay. Basically is a high impedance input buffer, a differentiator and a driver for each coil.
can u post the schematic to share with us?
Slick !!!
IIRC There was some demand for that kind of thing.
That is brilliant Roberto. I would also like to see the schematic for that. I have a bunch of boss pedals I'd like to true bypass.
Thanks. I'll try to post the schematics tonight.
Roberto,
Looks awesome! Very james bond. Where did you get the ..ehh.. red electrical condom? :shock:
syzygy
Quote from: RobertoThanks. I'll try to post the schematics tonight.
That would be much appreciated ...
Quote from: syzygyRoberto,
Looks awesome! Very james bond. Where did you get the ..ehh.. red electrical condom? :shock:
syzygy
I would guess a red shrink tube; can be bought here everywhere
Yes is shrink tube.
This is the schematic:
(http://www.thundertomate.com/varios/bossrelay.jpg)
and this is the internal boss flip-flop where the inputs are connected:
(http://www.thundertomate.com/varios/bossff.jpg)
Thanks that's great ...
Yes, thank you! Will try it soon on my Boss pedals.
Hmmmmm, I've read the schematic of the Boss RV-3 and I guess this can't be true bypassed this way.........
I true bypassed my rv3 by installing a 3pdt inside the casing...
Filing the head of the switch allows you to make the pedal 'look' like a regular boss pedal untill you tap it and notice the click....
However... The damn thing pops
Quote from: Roberto on August 30, 2005, 05:45:03 PM
This is the schematic: Â
(http://www.thundertomate.com/varios/bossrelay.jpg)
I was looking at this and found myself trying to find a way making with this circuit a fuzz box... :o ;D
That's an odd experience...
Quote from: John Egerton on October 21, 2005, 05:20:57 AM
I true bypassed my rv3 by installing a 3pdt inside the casing...
Filing the head of the switch allows you to make the pedal 'look' like a regular boss pedal untill you tap it and notice the click....
However... The damn thing pops
Resistor loads anyone?...
I've tried 1 meg pulldowns but it still pops...
Beautiful job!!! 8) 8) 8)
My approach to true bypass is a small DPDT installed at the place where the original momonetary switch located. Then i add a bypass circuit for the status LED. The DPDT switch is in similar height to the momentary switch so i can step on the pedal to ON-BYPASS it like usual
This would make one AMAZINGLY popular project, I think... Tonepad? GGG? ROG? Fuzzcentral?
...i'm a beginner, i need babysteps :icon_mrgreen:
This is BRILLIANT!! I have to say, i've never really had a problem with the input buffers on Boss pedals, since I have the one and only one worth owning (DD-3), but I guess if you have a couple it might improve the signal chain a lot. Would this be worth it, or even possible with a DD-3?? I'm guessing there's not a lot of real-estate inside that little case ;)
Very cool (and clever). :icon_cool:
....is asking for layouts (standard pcb) against a forum rule? because MAN would i love one.
Quote from: no one ever on November 06, 2005, 05:08:10 PM
This would make one AMAZINGLY popular project, I think... Tonepad? GGG? ROG? Fuzzcentral?
...i'm a beginner, i need babysteps :icon_mrgreen:
All the information you need is in this thread. Not to sound like a complete d*ckhead, but this is not a beginner's project - if you need step by step instructions, I strongly suggest working on other simpler projects first. There's far too many things to debug and go wrong, or just not work for no apparent reason. For example, relay coil noise that won't go away no matter what you do.
At the very least, for a project of this sort to go smoothly you should be able to trace the signal path of an effect WITHOUT a schematic (though one helps) as well as build a complete working effect from scratch with little/no help.
Quote from: cd on November 07, 2005, 11:10:44 PM
All the information you need is in this thread. Not to sound like a complete d*ckhead, but this is not a beginner's project - if you need step by step instructions, I strongly suggest working on other simpler projects first. There's far too many things to debug and go wrong, or just not work for no apparent reason. For example, relay coil noise that won't go away no matter what you do.
At the very least, for a project of this sort to go smoothly you should be able to trace the signal path of an effect WITHOUT a schematic (though one helps) as well as build a complete working effect from scratch with little/no help.
.. ok then, i'll assemble my own layout and such.
QuoteWould this be worth it, or even possible with a DD-3?? I'm guessing there's not a lot of real-estate inside that little case
AFAIK, all Boss pedals use the same bypass switching scheme. Therefore, it ought to work on a DD-3 just as well.
QuoteFor example, relay coil noise that won't go away no matter what you do.
Yes, that's a problem. The power supply for the realys circuit must be decoupled (RC filter, I use 100 ohm / 22uF... that filter don't appear in the schematics that I drew). Anyway, as you say, some "pop" coil noise are always present, even powering the switching circuit with a separate power supply.
Quote from: Paul Marossy on November 08, 2005, 03:13:53 PM
QuoteWould this be worth it, or even possible with a DD-3?? I'm guessing there's not a lot of real-estate inside that little case
AFAIK, all Boss pedals use the same bypass switching scheme. Therefore, it ought to work on a DD-3 just as well.
That's halfway right - virtually all BOSS pedals use the same momentary switch with flip flop which controls FETs, however the placement of those FETs and the routing of the bypass signal varies. In the SD-1, the FETs switch out the OD section. In the DS-1, same thing except with an added mute. In the DD-3, it's simpler, only the wet signal is disabled yet the signal still goes through the pre-emphasis/de-emphasis circuit. etc. etc.
Quotevirtually all BOSS pedals use the same momentary switch with flip flop which controls FETs, however the placement of those FETs and the routing of the bypass signal varies.
That's basically what I was getting at. :icon_wink:
does this use the low sensitivity omron relays?
That is so great! I didn't know there was such a thing as latching relays. If I'd known that I wouldn't have given up (temporarily) on my ultra-low-tech remote switching project. I'm just getting started with electronics, and this is such a gas - so useful.
This has been my approach to retrofitting Boss type pedals: "Hulk SMAAASH bypass! Grrrrrr."
(http://i23.photobucket.com/albums/b364/teledumpoff/Hulk-SMASH-TS5.jpg)
LOL - I'm so not clever... I'm getting really good with a Dremel cutting disc, tho.
How the hell did you mount the switch?
I just took my TS-5 and put it into another enclosure (Hammond 1590BB) and changed a few things around to make it true bypass (with much help from cd). I figured the cheapo plastic case would break sooner or later. It was a major pain in the arse for my 1st project, but I learned a lot.
Quote from: moandj on November 15, 2005, 03:12:47 PM
How the hell did you mount the switch?
Sorry - didn't mean to hijack the thread; I was just trying to show the end of the spectrum opposite genius...
I drilled out the indentation that lines up the spring and dremeled out the inside buttresses so the switch stood up high enough. Had to replace a couple caps so they could lie down flat on the PCB and clear the switch. Put the hinged lid back on and drilled it, too, to give it that not-thought-out-very-well look everyone likes. Next I'm gonna put some gold rims on it.
Then I'm gonna try this relay trick.
This can be reduced to two transistors and a 4.7uF capacitor. Buffer one of the sides of the flip-flop with a complementary transistor pair (npn and pnp) with the emitters tied together like a class B amplifier. Connect this to one side of a relay coil. Connect a 4.7 uF cap between the other side of the coil and ground. This configuration can be found with my spst switch driven relay driver circuit. All you're doing is using the complementary pair transistors as an on/off signal buffer from the flip-flop.
The two transistors can be glued to the ends of the relay, and the cap can be glued to the top or one of the sides depending on how it can be best arranged inside the BOSS pedal. Wire it up and heat shrink it like Roberto, and you have something in a smaller footprint.
The classic trade-off to this topology is that the LED is not always in synchronization with the relay state at power up. You have to tap the pedal once to get the LED to match the relay position right after you turn on the power --- not a big deal for me, but I can imagine somebody finding it a bit of a pain to tap the switches on 10 pedals in their pedalboard right after they power it on.
The alternative is Roberto's circuit, which is more parts, but does seem to fit in the space constrained box.
Very clever idea! :icon_cool: