Set-Reset flipflops do not need switch debouncing. Toggle circuits usually do.

Possible option: If you add pull up resistors from both D inputs to VCC, and insert removable shunts between D and Q-, the alternate-action functions of the two switches now are individually selectable in the field.

ak

The capacitor is not there for debounce, it is there to pop a reset of the other flip flop. If the reset remains low, that flipflop is no longer active for the next foot press.

 

The OP said, the "default" switch would turn the active state off and back to the initial startup state regardless of which state was active. It can be ignored in my circuit if you just

??

 

The capacitor is not there for debounce, it is there to pop a reset of the other flip flop. If the reset remains low, that flipflop is no longer active for the next foot press.

I didn't mention any capacitors, so I'm not sure what you are replying to.

I know what the caps are doing in your circuit, and why they are necessary. That's why I didn't do it that way. I'm saying that if you do not *add* debouncing to the switch inputs, the toggle circuits will not behave predictably.

Also, I do understand how differentiators work. In your circuit they also provide DC isolation to block an unwanted feedback path, which is needed because you drive the other circuit resets from the flipflop outputs. In #30, I drive the resets with the switch inputs, which are momentary and thus do not present a conflict, and diode-AND them with the Burn input. Same effect.

BTW - It is difficult to tell from a wiring diagram, but I think you want to drive the CLR- inputs with the Q- outputs, not the Q outputs.

#30 probably would look a bit less complex if it used a dual flipflop part such as the CD4013 instead of individual gates, but the overall body count is the same.

ak

 

I don't know to whom this is directed but I felt compelled to reply.

Every guitar amplifier hat I have ever seen has the default mode that when no effect is selected the default is no effect is applied, thus the clean mode.
BUT if an input is required for the third mode, that can easily be provided by a series connection of an NC contact on the two relays, with no additional relay required..

If you read post #39-40, you'll see I asked this questions about this, but the TS stated "Burn" was the default, which makes no sense to me. Neither does the description on how the pedal is activated. But I realize its the TS's choice.

I agree that "no effect active" (a clean, unaltered sound) should be the default when the pedal is first plugged in. I thought moving the selector switch to "remote" deactivated the panel selection, activated the footswitch capability, and made the default "clean". But apparently, that's not what remote does.

 

Just my opinion, but having a "default" mode on an effects unit is kinda strange.
Most guitar players I know ( and I know alot of em) don't want anything "on" until they step on a button.

In the circuit I posted, all the function are off at power up, and you step on a switch to begin.

Personally, I think using relays is a bad idea. There's plenty of vibration on stage (aside from stomping on the switches). If it were me, I'd use a solid state switching like MrSalts, but configure it for a 9v battery. Musicians always have 9v batteries or 9v adapters.

Yes, a power supply is not an issue. I always have 9-18 volts available on my stage rig.

 

Ok. Here's my attempt at a relay based version:
This uses 3 DPDT relays, 3 momentary footswitch buttons, and includes LED's
All switching is done via ground but can be easily changed to +5v.
This circuit will require a 5v supply, probably less than 100mA capacity, but could be changed to run the LEDs and relays from a 9V battery.
The buttons all operate in a mutually exclusive manner, with only one output active at a time.
Ignore the stuff in the "for simulation only" box.

View attachment 266803

Thanks you this looks great.

 

Thanks you this looks great.

If you want to use a 9V supply instead, change the relays to a 9v, low current type relay

 

From the photo of the initial effort, with all of those clip leads, my impression is that the buttons are Spdt, with both a normally closed contact and a normally open contact. If that is the case then only 2 relays are required, since the switch common NC connection can be used to release the opposite relay, with the third button releasing both of them.
Like I said at the beginning, not hard, but complex wiring. And forget those diodes for spike protection, because the indicator LEDs with the resistor will take care of that,
The basic circuit is unchanged, the cancel-all button breaks the main feed, and the NC contact on each effect button breaks the hold-in for the opposite relay, while the NO contact pulls in the selected relay. Of course if there were more than two effects to be selected it could not be done in such a nice manner.

 

From the photo of the initial effort, with all of those clip leads, my impression is that the buttons are Spdt, with both a normally closed contact and a normally open contact. If that is the case then only 2 relays are required, since the switch common NC connection can be used to release the opposite relay, with the third button releasing both of them.
Like I said at the beginning, not hard, but complex wiring. And forget those diodes for spike protection, because the indicator LEDs with the resistor will take care of that,
The basic circuit is unchanged, the cancel-all button breaks the main feed, and the NC contact on each effect button breaks the hold-in for the opposite relay, while the NO contact pulls in the selected relay. Of course if there were more than two effects to be selected it could not be done in such a nice manner.

If your referring to my post…leave the spike protection diodes in, the LEDs do not provide reliable EMF protection.

 

Getting the diode polarity reversed will cause all sorts of problems. Definitely not the sort that a newbie will want to be struggling with.
So how about adding the diodes after the system is working?

 

Getting the diode polarity reversed will cause all sorts of problems. Definitely not the sort that a newbie will want to be struggling with.
So how about adding the diodes after the system is working?

The TS was able to figure out the switching, should be able to handle the diodes...

 

It would be helpful to know if any of the available (XLR?) pins on the amp is directly connected to 5V (as a useful LED supply), or whether all "5V" pins are connected via pull-up resistors to 5V.
@Leighz1
Could you connect a ~1k resistor between T and S (or R and S), ground the XLR pins via 1k in turn, and in each case measure the voltage across the resistor?
If we can deduce the source impedance of the pins this could avoid over-engineering (or under-engineering) a solution to your switching requirement.

 

The connector shown is not in the "XLR" family. And a question: Is the multi-pin connector simply in parallel with the two TRS-quarter inch connectors? Or is there a separate set of connections to different circuits internally?

The big advantage of using relays for the switching is that the control voltages are totally isolated from the controlled circuits. That certainly was important in some of the older tube type amplifiers.

 

Getting the diode polarity reversed will cause all sorts of problems. Definitely not the sort that a newbie will want to be struggling with.
So how about adding the diodes after the system is working?

I appreciate the advice here. I have built several guitar amps but nonetheless I am new to a lot of these schematics. Thanks again.

 

This is an example of what is called "dead bug assembly". You glue down the parts with the legs pointed up, and then wire the circuit point-to-point with insulated wire. I've found that solid wire is easier to work with because it stays in place when you bend it. If you glue down each relay with a small dab of RTV, and tack on about 4" of wire to each pin, you should be able to wire up everything in an hour or two. Not counting the wires from the isolated contacts to the connector, it looks like around 10 wires in the #34 schematic (plus things like LED indicators ans suppression diiodes).

The photo shows copper-clad pc board material, but you don't need anything like that. In fact, you probably can glue the relays directly to the case in-between the switches.

What type of switches are you planning to use? Photo?

ak

 

For the amplifier control foot-switches, reliability is usually quite important because they are also used in performances. And consider that they are also referred to as "stomp switches" by many folks.Besides that, traveling to Gigs and setting up often includes harsh treatment. So I suggest that the dead bug assembly system is not appropriate for this application.

 

For the amplifier control foot-switches, reliability is usually quite important

I knew someone would pipe up. Actually, that is why I recommended RTV rather than hot-melt glue - it is *the* standard adhesive in shock and vibration environments. Plus, the TS already has good wire management technique.

I built about a dozen stomp boxes back in the 80's using a variety of techniques, including dead-bug relays in two of them. Worked for decades.

ak

 

If you want to use a 9V supply instead, change the relays to a 9v, low current type relay

The lowest current ones I could see online specified 16.7mA coil current. Two or three relays, plus indicator LEDs, would be a significant drain on a poor little 9V battery.

 

The lowest current ones I could see online specified 16.7mA coil current. Two or three relays, plus indicator LEDs, would be a significant drain on a poor little 9V battery.

Only one relay and LED on at a time...

 

Only one relay and LED on at a time...

Thanks again for the technical support. Power is not an issue as I can always find 9-18V on stage, but I think I can tap into the 5V power supplied by the amp.