Actions
Forum Thread Details
  • State Suggested Answer
  • Replies 2 replies
  • Answers 1 answer
  • Subscribers 303 subscribers
  • Views 1078 views
  • Users 0 members are here
Related
See a helpful answer?

Be sure to click 'more' and select 'suggest as answer'!

If you're the thread creator, be sure to click 'more' then 'Verify as Answer'!

Momentary Guitar Footswitch Mode Toggle Modification

warezwally

Hi Guys,

 

I am learning as I go here and I have set myself a challenge...

 

My guitar amp is switched by a 4 button footswitch all switches are momentary and the channel switching logic is done (I believe) in the amp by a pulse to ground over each switch.

 

Clean, OD1, OD2 & Reverb

 

The footswitch is connected over a DSub9 and the pinouts (from memory) are:

 

1 - Clean LED Anode

2 - OD1 LED Anode

3 - OD2 LED Anode

4 - Reverb LED Anode

5 - 0v

6 - Clean

7 - OD1

8 - OD2

9 - Reverb

 

 

What I'd like to do is repurpose the switch on OD2 for something else, so I was thinking I could use the OD1 switch as a toggle between OD1 & OD2 modes. The research I've done has led me to believe that I can do this by using a combination of JK Flip-Flop and 556 (or 2x 555) timer as a one-shot monostable:

 

Here is my circuit, is this right? What's missing and what resistor values do you suggest I use to with the 10uF polarised caps I'm going to use to allow a very quick pulse (HIGH) from the 556?:

image

 

The 556 outputs will go to a pair of NPN's (not LED's as shown) that will pull the pins 7 or 8 to 0v (pin 5)

Parents
  • 0

    Starting at the beginning, the switch will almost certainly bounce when you press it. [The contact, instead of landing cleanly, bounces and then breaks and makes a few times before settling. If you have an oscilloscope, wire up just the switch and the resistor and capture the waveform.]

     

    So you'll probably need to debounce the switch to stop it clocking the flip-flop more than once.

     

    Here's what an old momentary toggle switch that I fished out of a spares box looks like on a 9V supply with a 10k down to ground.

     

    image

Reply
  • 0

    Starting at the beginning, the switch will almost certainly bounce when you press it. [The contact, instead of landing cleanly, bounces and then breaks and makes a few times before settling. If you have an oscilloscope, wire up just the switch and the resistor and capture the waveform.]

     

    So you'll probably need to debounce the switch to stop it clocking the flip-flop more than once.

     

    Here's what an old momentary toggle switch that I fished out of a spares box looks like on a 9V supply with a 10k down to ground.

     

    image

Children
No Data