Help with my Wah Wah

[djstumerch]

Hi everyone I'm new to the forum as well as the world of electronics. I'm working on a project (wah wah pedal) and I'm just wanting some clarification as well as a little help. I have attached a photo of the schematic to help. The switch for turning the device on/off does not seem to work. Does it connect to the positive rail as well as pin 7?

I also bought a SPST foot switch which will activate the wah effect as pointed out in the parts list. This however should have been a SPDT switch with three pins. Is there anyway of modifying the schematic to allow an spst switch to work?

Thanks

Stuart

 

[KMoffett]

Maybe, but it would requiring extra circuitry and would probably cost you more than buying the right switch.

Ken

 

[BrownOut]

Does it connect to the positive rail as well as pin 7?

Um. Pin 7 is already connected to the positive rail. They are one in the same.

Is there anyway of modifying the schematic to allow an spst switch to work?

What switch did you buy? Are there swtiches especiall for this application? Can you get a foot switch correctly configured? If not, you might have to try to make some kind of contraption to hold two SPST switches. Otherwise, you're gonna open a can of worms trying to mod the circuit, as post #2.

 

[djstumerch]

Thanks for the replies

I hav just been to maplin get another switch, the only ones they had were a DPDT so this would do the job right? Just use one side of the connecters?

That should solve one problem, the other is the on/off switch. I'm unsure where to connect the cables. Looking at the schematic it seems both are connected to positive? The chip is a LF351N if this helps?

Thanks again for your help

Stuart

 

[House0Fwax]

That should solve one problem, the other is the on/off switch. I'm unsure where to connect the cables.

The on / off switch is connected between the positive (usually red wire) from your battery supply and the rest of the circuit.

 

[KMoffett]

As an aside...and not knowing all the details of using a Wah-Wah peddle...and to add to your confusion ......The DPDT switch could be wired to power the circuit only when the in the Wah-Wah mode and not use the battery when in the bypass mode. That would replace S1 and S2 with the one switch. Don't know if that would cause problems with the sound as that circuit took a finite amount (miliseconds?) to power up.

Just a thought.

Ken

 

[djstumerch]

Switch problem

Hi guys thanks for you getting back to me and helping me with my project. Think I'm finally getting somewhere but the switch is still bewildering me. I have attached two photos, one a close up which shows my circuit on a strip board. I have used jumper cables on this project (my first) rather than etch out the copper rails underneath. I did this for the IC though.

I would be very grateful if any of you could point out where the switch would go.

Thanks again

Stuart

 

[House0Fwax]

I would be very grateful if any of you could point out where the switch would go.

The switch goes in the battery positive lead.

 

[djstumerch]

Thanks

Thanks again everyone for your help. Sure I'll be back here soon asking questions regards future projects.

Cheers

Stu

 

[djstumerch]

Converting Voltage to Resistance

Hi everyone, I am wanting to use an LFO module I have created to modulate my wah wah effects pedal. I have been advised at university that I will need to change the voltage output from the LFO to a resistance. How will I do this? I know I will need to use a transistor but have no idea where to start?

My other query is where my output from the LFO will input to the wah wah?

Any help would be great. I have attached both schematics for both modules.