Does anyone have a true bypass schematic for a momentary relay setup?

[acehobojoe]

And for me when I think about the sheer amount of things people have done with the technology. 

It is amazing to look at all of the little chips that are designed to do every process imaginable.

[R.G.]

I actually just meant a relay that can be used with a momentary soft touch to supply that pulse it needs.

There aren't any relays that do that on their own. There are relays that must be held on, and "relax" to an off state - non-latching, that is; and relays that will latch to either state. But no relays I've seen will do the flip-flop operation of flipping to the opposite state with a single switch closure. There's an article on just relays and how they work at geofex.com, too.

I'm not super concerned about battery, as most of my pedals I just run on 9v supply.

For this, a single latching footswitch works fine. The footswitch supplies the flip-flop function. Latching relays are screamingly useful for turning off the 9V power when the relay has moved to a new position.

I've also seen the "click less true bypass" by jack deville. I'm guessing his is similar to one of the transistor setups above with a TQ2-L2-5V Relay.

It's almost certainly a latching relay driven by an 8-pin microprocessor. Pretty straightforward. But not clickless unless some other criteria are met. And every relay I've ever heard clicks at least a little. Never could figure out that name.

[Groovenut]

The JD Clickless Truebypass (now Mammoth Electronics Clickless True Bypass) uses a Microchip PIC12f509

[R.G.]

Microchip Technology if it's a 12F509. $0.65 each in 25 piece lots.  Cheaper in SMD. 8 pin dip.

A CD4049 costs $0.43 in 10s, and needs a couple of transistors and a few other parts. 16. pin dip.

Shrug.

[MrBinns]

>It looks like I'll be trying out the 4053 CMOS driven by the CD4049. I'm not sure if this is the most efficient way, but it looks simple enough.

>For some reason my eagle software won't let me draw in the supply pins though, I may have to manually route pin 1 and 5 of the 4049 to supply as with the 4053.

I bread boarded something similar recently for a larger circuit I'm working on. It's pretty cool. The reset on power section brings 'R' high when the power is first applied. This resets Q to low. Then 'R' drops low and with 'S' being low it puts the j-k flip flop in changeable mode. J and K get tied together to high so the j-k flip flop acts like a t flip flop(toggle). Than whenever you press the momentary switch it toggles Q low/high and that activates the true bypass switch part.

[acehobojoe]

I guess the question remains if it's better to do pic chip technology or to just use the CMOS stuff

[Transmogrifox]

I guess the question remains if it's better to do pic chip technology or to just use the CMOS stuff

If you're comfortable programming, or you want to learn and give it a go, this is a good project for learning how to use microcontrollers.

If you just want to get it done without ramping up the learning curve on uC programming then just stick to the CMOS IC's or 2-transistor flip-flops.

For example, the typical BOSS pedal bypass can be easily connected to a pair of transistors through capacitive coupling like RG's dual-coil latching relay schematic and do the same thing.

I linked a schematic/thread earlier in this thread that converts a momentary switch to an on/off toggle to a single coil latching relay or it's a 2-transistor circuit if you use a standard non-latching relay.

Along with a microcontroller you also need to create a 3V to 5V rail for the thing.  Not complicated, but it's yet another part.

More and more I'm finding that a microcontroller isn't really a great benefit unless:
A) Complex switching logic (like switch one enables relay 3, disables relay 1 and allow switch 2 to toggle relay 2, and switch 3 masks switches 1&2 functions and toggles relay 1).
B) Lots of different switches (amp channel 1, amp channel 2, FX loop, reverb or looper matrix)
C) Microcontroller can be used to do something interesting in your circuit like tap tempo, or LFO waveshape generator.

If it's just a simple on/off with a momentary pushbutton try the 4-transistor circuit or CMOS equivalents.

As RG stated above, one way of skinning this cat can't really be held very high above another. 

I can certainly suggest some really complicated ways to do it.  If you really want to use a sledgehammer for a tack, then implement this on a $50 FPGA in a BGA package and see how well you solder hair-sized wires onto a dead-bug mounted FPGA.  Then implement some logic to count the number of switch presses, the on time vs off time, etc., and store the log in some external RAM and compute statistics on the data every once in a while.  Then you need to implement a USB interface so you can use your computer to access the statistical data. It will serve as a pedal scoring card if you get to a point of trying to decide which pedals to take off your pedal board when you run out of space. That would keep you busy for a few months I'm sure  

[R.G.]

I guess the question remains if it's better to do pic chip technology or to just use the CMOS stuff

As I keep flogging people to think about, "better" has no meaning unless you also state the metric you use to measure how much good-ness each version has.

8-pin PICs (and other uCs) are smaller, and vastly more capable in terms of being able to do more fancy stuff, as noted. 14/16/18 pin uCs can do many switches and complex states at the same time. I have a set of code I re-use over and over that will read many switches in parallel, debounce them, then set an output from the switches to complicated states; some of these are to make one momentary switch have a momentary or alternate-action operation depending on the state of another pin (or program variable) so you can have Mark Hammer's favorite, a footswitch that can be *either* off/on or momentary, on the fly. And they do this at very nearly the same cost as hard logic.

On the other hand, hard logic, whether CMOS gates or transistor logic, is much easier to understand. Some people have a strong aversion to programming, and perhaps with good reason. I have programmed in probably a dozen languages, and have no fear of adding a new one, but that's not typical. I also can't do intense, operating-system style programming. It gets complicated. Sometimes, simple is better IF your metric is to have both low cost and easy to understand.

This is an intellectual extension of the exchange between Alice and the Cheshire Cat:

    "Would you tell me, please, which way I ought to go from here?"
    "That depends a good deal on where you want to get to," said the Cat.
    "I don't much care where—" said Alice.
    "Then it doesn't matter which way you go," said the Cat.
    "—so long as I get SOMEWHERE," Alice added as an explanation.
    "Oh, you're sure to do that," said the Cat, "if you only walk long enough."

If you don't know what better is, and you just do something, you'll eventually get to better - and decide how it's better once you get there.

Setting objectives is crucial.

[acehobojoe]

 

That would keep you busy for a few months I'm sure  

Well, I'm making it a goal to just learn as much as I can in my spare time. I could try reading a geofex article a day or something 

I'll probably stick with the non microchip one for now, I want to grab a pic programmer, but I'm not sure where to start! I might just start with an already existing code and just figure out how to make it program with my computer.

I would like to put a simple 2 chip bypass design on pedals just for kicks.. but really, it does kind of help with the hassle of a 3pdt! It's way more components, but not too bad if you're really fast 

I doubt it will be "worth it" in the end, but it's just another trick to add to my mind.

[acehobojoe]

I guess the question remains if it's better to do pic chip technology or to just use the CMOS stuff

This is an intellectual extension of the exchange between Alice and the Cheshire Cat:

    "Would you tell me, please, which way I ought to go from here?"
    "That depends a good deal on where you want to get to," said the Cat.
    "I don't much care where—" said Alice.
    "Then it doesn't matter which way you go," said the Cat.
    "—so long as I get SOMEWHERE," Alice added as an explanation.
    "Oh, you're sure to do that," said the Cat, "if you only walk long enough."

If you don't know what better is, and you just do something, you'll eventually get to better - and decide how it's better once you get there.

Setting objectives is crucial.

Great advice for getting a start anywhere in life.

[bluebunny]

. . . I'm not sure where to start

This might be a good place to start.  Have a read.  I'm a microcontroller noob and it seems like an easy way in.