555 Timer Momentary Soft Touch Relay Bypass circuit Troubleshooting

[Senor Avocado]

Hey guys,

I had a quick question on what might be causing my current issue with my pedal build.

I built two of these layouts from the perfboard layouts website to put in a dual overdrive build that I was working on.

It is the 555 Timer Momentary Soft Touch Relay Bypass circuit. When I tested them individually, they worked great, I was able to get the LED to turn on and change the state of the relay with the momentary switch. The issue I have now though is when I connect the ground and power of the 2 individual circuits and power them from the same power supply. If I want to try and run both effects at the same time in series, I cannot get both LEDs to stay on. For example, if the switch is engaged for Effect #1 and has the indicator LED on, when I go to turn on Effect # 2, it will turn off the LED for Effect #1 and then illuminate the LED for Effect #2. Right now it is functioning more like channel select switchs which is cool, but not what I am trying to achieve with this build. It is almost like the two circuits are somehow interfering with each other.

I am not sure if there is a way to better isolate the 2 circuits to prevent the cross talk or what other steps can be taken to resolve the issue

I hope that makes sense and I am hoping to tap into your brains to see If I can fix it!

Thanks!

[PRR]

> I hope that makes sense

We may want to see the actual schematic; sussing the workings of a layout is too hard.

However I would assume that such a neat drawing probably works, especially as you say each one does work.

Then it is probably not the modules but _your_ wiring. Draw that out so we can see what you got.

A dim stab: a very weak power supply may drop-out when the second relay comes on, and that may upset both modules. However it would have to be quite weak. And it is unlikely it would make a reliable flip-then-flop as you report.

[Senor Avocado]

Thank you PRR for your response! I did double check my wiring and was going to draw something up something to show you all but I got the opportunity to troubleshoot some more yesterday and was able to get both modules working together!

I was looking at how sometimes in power supply filtering there is a 100R resistor in series with the 9v supply so I implemented that here! I put 1 resistor for each module and then after that no more cross talk!

Thanks again!

[Kipper4]

Is this it ?


http://stompville.co.uk/?p=260

[trixdropd]

I would highly suggest you modify your layout with the relays to ground the input of the effects send when bypassed. This will result in a quieter setup with high gain equipment.

[Rob Strand]

Is this it ?

It's more like this:
http://talkingelectronics.com/projects/50%20-%20555%20Circuits/images/Toggle.gif

but with the output driving some transistors and the LED; and 10n on pin 5 of the NE555.

Had a look the other day but gave up.  It's hard to give advice off those layouts.  You spend more time tracing the circuit than helping!

I was wonder if the Senor Avocado is using one switch and two circuits?   That will screw things up.
All switch contacts must be completely separate, no common wires.

[Groovenut]

Is this it ?

It's more like this:
http://talkingelectronics.com/projects/50%20-%20555%20Circuits/images/Toggle.gif

but with the output driving some transistors and the LED; and 10n on pin 5 of the NE555.

I've used this configuration before and it's solid. Though I would recommend the CMOS version of the 555 as it wont crowbar the V+ rail, keeping things quieter. Be aware the CMOS version has lower drive capacity but that really doesn't matter too much if your driving your loads with transistors.

[Rob Strand]

I've used this configuration before and it's solid.

The idea seemed OK to me too, it's used in many pedals just not with 555's.