Need a footswitch schematic for a guitar amp

Thread Starter

Leighz1

Joined May 7, 2022
21
I need a 3-button footswitch where one switch shorts the tip of a TRS phono plug, one switch shorts the ring and one cancels the shorting. I want to step on any switch and get the needed response regardless of the last switch pressed. The amp I have can be switched through 3 channels this way. When the tip of the TRS is shorted it will switch to gain. When the ring is shorted it will switch to clean and with no shorting it will return to burn or high gain.
Does anyone have a schematic? Is there anything like this available?
One switch shorts tip and clears the short on ring. One switch shorts ring and clears short on tip and the third switch clears both ring and tip?
In addition, it would be nice to have led lights.
Please let me know if you can help, cheers.
 

MisterBill2

Joined Jan 23, 2018
11,880
It sounds like you already understand the connections, but really that would be a two button foot switch, each button being alternate action, which is common: Push ON, Push OFF. That is the normal scheme with a "stomp switch", which are the rugged ones. I have not seen mechanically interlocked button switches that would last with foot operation. A setup like you describe using the durable mechanical switches that I am familiar with will require some internal electronics and also some power source. It would also require knowing how the amplifier that you are using it with is controlled.
So yes, ia box can be built that will do exactly what you describe, but it will require external power and it will be a bit more complicated than just having two alternate action switches.

BUT there may be another option: I have come across a company that sells all sorts of electronics for the music performance crowd. It is called "Sweetwater", and they may possibly already have the product you described. They have a really good website, so I suggest contacting them and describing what you want.
 

eetech00

Joined Jun 8, 2013
3,154
I need a 3-button footswitch where one switch shorts the tip of a TRS phono plug, one switch shorts the ring and one cancels the shorting. I want to step on any switch and get the needed response regardless of the last switch pressed. The amp I have can be switched through 3 channels this way. When the tip of the TRS is shorted it will switch to gain. When the ring is shorted it will switch to clean and with no shorting it will return to burn or high gain.
Does anyone have a schematic? Is there anything like this available?
One switch shorts tip and clears the short on ring. One switch shorts ring and clears short on tip and the third switch clears both ring and tip?
In addition, it would be nice to have led lights.
Please let me know if you can help, cheers.
What is the Amp model?

What type of signals are being switched?
DC? Audio?
 

Thread Starter

Leighz1

Joined May 7, 2022
21
It sounds like you already understand the connections, but really that would be a two button foot switch, each button being alternate action, which is common: Push ON, Push OFF. That is the normal scheme with a "stomp switch", which are the rugged ones. I have not seen mechanically interlocked button switches that would last with foot operation. A setup like you describe using the durable mechanical switches that I am familiar with will require some internal electronics and also some power source. It would also require knowing how the amplifier that you are using it with is controlled.
So yes, ia box can be built that will do exactly what you describe, but it will require external power and it will be a bit more complicated than just having two alternate action switches.

BUT there may be another option: I have come across a company that sells all sorts of electronics for the music performance crowd. It is called "Sweetwater", and they may possibly already have the product you described. They have a really good website, so I suggest contacting them and describing what you want.
Thanks for the response. Yes you can control this amp with a 2 button footswitch. That is how I have been using it but you have to remember where you are at with the switches. There is a way to build a three button switch though. The amp originally came with one. The builder will not provide a schematic. I have gotten very close using a 3 button switch and alligator clips with NO and NC options on every switch. I can step on any switch and it will go there with the exception of one combination. If the ring and tip are both shorted there is no sound from the amp. There is also a way to connect the switching using a 6 pin connector that has 5 vdc on each pin.Kasha switch input jack.png
 

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Thread Starter

Leighz1

Joined May 7, 2022
21
It sounds like you already understand the connections, but really that would be a two button foot switch, each button being alternate action, which is common: Push ON, Push OFF. That is the normal scheme with a "stomp switch", which are the rugged ones. I have not seen mechanically interlocked button switches that would last with foot operation. A setup like you describe using the durable mechanical switches that I am familiar with will require some internal electronics and also some power source. It would also require knowing how the amplifier that you are using it with is controlled.
So yes, ia box can be built that will do exactly what you describe, but it will require external power and it will be a bit more complicated than just having two alternate action switches.

BUT there may be another option: I have come across a company that sells all sorts of electronics for the music performance crowd. It is called "Sweetwater", and they may possibly already have the product you described. They have a really good website, so I suggest contacting them and describing what you want.
Thanks for the response, Sweetwater is a great source but I have looked at every option there. Unfotunately I need something very specific to this amp.
 

eetech00

Joined Jun 8, 2013
3,154
It is called a Kasha. This was custom built for a known player. The switching on the amp is triggered by shorting the tip and the ring. It also has a 6-pin connector that has 5 vdc on each pin.
Wow...that's a cool snake skin amp head. :cool:

I think I can draw something up...but will take a little while...
It might take more than just buttons though....
 

AnalogKid

Joined Aug 1, 2013
10,055
A set of switches where any one switch cancels the actions of any/all other switches is called a bail function. This is common in a row of pushbutton switches or activators, such as the buttons on a (old) car radio. Hence, the name for an electronic circuit to do the same thing is called a "radio button" circuit. A search for that term will yield lotsa schematics, and there have been several threads on this and other fora.

The core of this type of circuit is a latch, or one latch per button. That is why one response said a switch box would need an external power source. My *guess* is that while many of the pins on the connector have 5 V on them, at least one of them is a 5 V supply to run the bail circuit, while the other 5 V inputs are in fact held at 5 V through a pull-up resistor, and you activate that input by pulling that pin to GND. Really need an amp schematic, but some careful poking around with a voltmeter and resistor might tell us which pins are sources and which pins are inputs.

Also, since putting electronics in a stomp box is by definition less reliable than putting them inside an amp (the word "stomp" is a clue), I gotta wonder if the only thing needed externally are switches, and the switching and bail functions are already inside the amp.

1. Are "Remote SW 1" and "Remote SW 2" TR, TRS, or other?

2. What do they do?

3. You have identified four of the six pins of the foot switch connector. Any idea what the other two do?

Interesting source for schematics, but nothing exactly matching your description:
http://millerguitar.com/schematics/

This sounds like it might be for your amp. Do you know if yours is based on the Rockmod I, II, or III - ?
http://www.instituteofnoise.com/bi/kashaman.html

ak

ps. Where are you located?
 
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MisterBill2

Joined Jan 23, 2018
11,880
OK, the function as described can be done with two relays, each having two sets of normally open contacts. The good news is that having indicator LEDs will be an easy add-on. two of the switches can be normally open, push to close momentarily. The third switch will need to have a normally closed contact, push to open. The circuit will be identical to the latching on circuit for motors.
The normally closed switch will be in series with the power to both, , and then each relay will have one set oof normally open contacts in series with the coil, fed by the power through the NC button. Then the NO contacts will have a NO button in parallel. So when a N.O. button is pushed, that relay will energize and stay energized when the button is released. It will be released when the third, NC button is pushed.
The indicator LEDs can be connected across the relay coils. If 5 volt pilot light LEDs are used then series resistors will not be required, only observing the correct polarity.
The second set of contacts will be used to connect the tip, ring, and sleeve circuits as required to enable the functions as listed in post #1. Use 5 or 6 volt relays and power them from the 5 volts available from the guitar amplifier. Or from a transformer type wall wart supply.

Probably it would be very simple to implement the whole control scheme via that six pin DIN connector but unfortunately the TS does not have the technical skill to check the connections and let us know where the DC supply is connected.
So the scheme with relays will work but possibly be more complex.
 
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Thread Starter

Leighz1

Joined May 7, 2022
21
A set of switches where any one switch cancels the actions of any/all other switches is called a bail function. This is common in a row of pushbutton switches or activators, such as the buttons on a (old) car radio. Hence, the name for an electronic circuit to do the same thing is called a "radio button" circuit. A search for that term will yield lotsa schematics, and there have been several threads on this and other fora.

The core of this type of circuit is a latch, or one latch per button. That is why one response said a switch box would need an external power source. My *guess* is that while many of the pins on the connector have 5 V on them, at least one of them is a 5 V supply to run the bail circuit, while the other 5 V inputs are in fact held at 5 V through a pull-up resistor, and you activate that input by pulling that pin to GND. Really need an amp schematic, but some careful poking around with a voltmeter and resistor might tell us which pins are sources and which pins are inputs.

Also, since putting electronics in a stomp box is by definition less reliable than putting them inside an amp (the word "stomp" is a clue), I gotta wonder if the only thing needed externally are switches, and the switching and bail functions are already inside the amp.

1. Are "Remote SW 1" and "Remote SW 2" TR, TRS, or other?

2. What do they do?

3. You have identified four of the six pins of the foot switch connector. Any idea what the other two do?

Interesting source for schematics, but nothing exactly matching your description:
http://millerguitar.com/schematics/

This sounds like it might be for your amp. Do you know if yours is based on the Rockmod I, II, or III - ?
http://www.instituteofnoise.com/bi/kashaman.html

ak

ps. Where are you located?
I'm located on the Central Coast California.
I have found remote sw 2 is TRS and controls the channel switching.
The remaining two pins do not switch channels but make speaker noise when grounded even on standby. I am assuming they control the effects loop.
Thanks for the response.
 

MisterBill2

Joined Jan 23, 2018
11,880
If the original remote pedal contained any active devices then one of those pins may have been a power source for those devices. In which case it could simply power the small relays that I suggested using..
 

MrSalts

Joined Apr 2, 2020
1,762
What happens if an effect is active (ring or tip) and you step on that switch a second consecutive time? Does it toggle back to "clean"?
 

MisterBill2

Joined Jan 23, 2018
11,880
What happens if an effect is active (ring or tip) and you step on that switch a second consecutive time? Does it toggle back to "clean"?
Not if the relay scheme is used. Once set the only choice becomes reset, done with the reset button. Repeated "ON" commands have no effect. The Latch/Unlatch system is not subject to repeated input problems.
 

MrSalts

Joined Apr 2, 2020
1,762
Not if the relay scheme is used. Once set the only choice becomes reset, done with the reset button. Repeated "ON" commands have no effect. The Latch/Unlatch system is not subject to repeated input problems.
Sorry for the confusion, I wasn't asking what your design does. I was asking the OP what he wants.
 

eetech00

Joined Jun 8, 2013
3,154
There is a way to build a three button switch though. The amp originally came with one. The builder will not provide a schematic.
Any chance you could get a photo of the original switch?

I have gotten very close using a 3 button switch and alligator clips with NO and NC options on every switch. I can step on any switch and it will go there with the exception of one combination. If the ring and tip are both shorted there is no sound from the amp. There is also a way to connect the switching using a 6 pin connector that has 5 vdc on each pin.
1. In the earlier post, you said you "shorted" the pins to get it to work. What did you mean by that? Shorted to what?

2. Also, you said the 6 pin connector has 5v on each pin. Then.....what is being switched?

3. How do you intend to connect this new footswitch to the amp? with a TRS cable?

4. Do you know which pins actually need to be switched? I ask because in looking at a schematic (I don't know if it is actually represents your amp), the tube inputs are shunted to ground when each switch is closed. I'm not a tube person, but I think that would shunt the input signal to that particular effect and shut it off (clean, S4, for example).

See below:

1651987909209.png
 

MrSalts

Joined Apr 2, 2020
1,762
Any chance you could get a photo of the original switch?



1. In the earlier post, you said you "shorted" the pins to get it to work. What did you mean by that? Shorted to what?

2. Also, you said the 6 pin connector has 5v on each pin. Then.....what is being switched?

3. How do you intend to connect this new footswitch to the amp? with a TRS cable?

4. Do you know which pins actually need to be switched? I ask because in looking at a schematic (I don't know if it is actually represents your amp), the tube inputs are shunted to ground when each switch is closed. I'm not a tube person, but I think that would shunt the input signal to that particular effect and shut it off (clean, S4, for example).
1) "shorted" means connected. In this case, to ground.
2) all the pins (except ground) appear to be 5v because they either supply 5v or have a pull-up resistor. The pull up resistor is needed so there is no dead short between 5v supply and ground when the switched pin is "shorted" to ground.
3) tbd
4) see the image in post 6. The three pins not labelled ground must be shorted to ground to switch to the labelled effect where "clean" disables either of the other two effects. Clean is actually the lack of any effect.
 

AnalogKid

Joined Aug 1, 2013
10,055
That is not the correct schematic. None of the switch locations have +5 Vdc in the open condition. Plus, the (maybe correct) manual clearly indicates TTL control of analog switch functions. The switches might be relays, but my read of the text implies solid state analog switches (or switch circuits) of some kind.

ak
 

Thread Starter

Leighz1

Joined May 7, 2022
21
What happens if an effect is active (ring or tip) and you step on that switch a second consecutive time? Does it toggle back to "clean"?
If you step on the same switch it just goes back. The issue is if both ring and tip are shorted it goes to nothing. I need to be able to go directly to the channel needed.
 
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