electronic switching, grumbling, and more

[kvb]

I am working on a Tremulous Panneur that has two speeds and a defeat feature.
I am using a 4049 and a 4053 as illustrated by R.G.

Everything is working just fine, except that I can hear the switch.

The speed switch toggles between two different pots. This is actually the worse of the two. I can hear the switch bottom out, and I can hear the switch as it is released.

The defeat feature disconnects the LEDs at the LDR from the LFO and connects them to 9v through a pot for volume control. (The LEDs need to be switched at both anode and cathode because of another modification that I will explain when this thing is done.) I thought the clicking here had something to do with the LEDs being disconnected. Putting a resistor and cap on the control to slow down the switching only made the click worse.

I'm bummed out. The whole point of using momentary switches is first, to learn about this stuff, the second thought was that if I was playing at low volume I could turn the thing on/off and change speeds quietly.

I took out the 4049 and switched the 4053 manually with clips. I could still hear a small click.
This tells me two things: One, that the 4049 is not necessarily the source of the click. Two, that the switch itself is a bit noisy.

Why can I hear the switch?

I may try the 4013 and see if that somehow isolates the sound of the switch a bit better.
If that does not work, then what am I going to do?

The thread talking about LDRs makes me want to try that. BUT that is going to involve many LED/LDR – 8 for a 4 pole switch – and then something is still going to have to do the flip flopping. Plus because the LDRs are imperfect the resistance will mess with the LED brightness.

So, I will be trying J270 P FETs, or J201s, or BS170 mosfets. This will help deal with the problem of things being disconnected/reconnected. But, I am still wondering what I am going to do if after all of this work I end up still hearing the click.


I suppose I am posting this in hopes that someone else has had this problem and may be able to offer some advice or maybe a link to some other switching scenarios.



OOHH!  What about an LDR at the 4053's control? That would isolate the 4049 and switch from the 4053.
See, there's a good reason to talk this stuff out.

Any other ideas? Thanks

[gez]

I have a Dano pedal with 4053 switching.  It makes a feint click whenever engaged.  It's acceptable.

Without seeing a partial schematic showing how you've done the switching, it's difficult to advise.  If you're connecting/disconnecting a LED via switching then there's scope for create spikes due to the sudden introduction/disruption of current.  Make sure you have a separate grounding path for the LED.  Also, use a low-current LED (if you can) to keep current down.

[kvb]

I put the LDR on the 4053's control. It is switching just from the light in the room. I can toggle the switch just by making a shadow over the LDR. There is still the switching noise. So it must be as Gez says - "spikes".

The weird thing is that I can get the switch to be kind of in between, if I hold my hand just right.  The circuit starts picking up radio.


I think that I am going to have to try LDRs or FETs for the switching and see if I can set things up to be something like a "make before break" switch.

Maybe move the cathode first and then the anode.