Best place to put a DC filter (noise reduction) cap

[jsleep]

I'm sorry Mat, I didn't mean to confuse things, just trying to find out the switching so I could discuss it.  I think this is the typical switch (to ground) that most of us use and it is the same idea I use on GGG diagrams.

Maybe I'm a "special" case, but I have yet to find, in my own personal experience, any scheme of filter caps  (placed anywhere in the circuit) that stops switch pop caused by the LED.    My poster child for LED POP is the Stratoblaster in stompbox form.  The only thing I could find that would stop the pop was putting the switching on a Geofex Millinium 2 switch.   Most of the verbiage on the internet about the Mil-2 switching is to save money on those darn expensive, hard to find 3pdt switches.  The thing is now days, (in USA anyway) they are not expensive and not hard to find.  So, it actually took me a while to try it as a pop suppressor.  Whadda ya know, it worked! and now I have an extra SPDT switch unused on my 3pdt footswitch :-)  I tried everything else I could think of, including filter caps all over the place, everything on AMZ, 4066 switching (which seem to have small click through the amp), etc, etc.

That being said, most stompboxes that I've built don't have any problem with LED caused pop, even with no filtering.  so my default is not to take any precautions and deal with it if there is switch click.

JD

[PRR]

> I suggest that the LED be powered directly from the raw +9v and not from the filtered supply

Right, and not only in electronics.

My house gets water from a well. Not real deep, and the rock here is a little nasty. We filter the well water.

But filters are expensive. We filter only as much as needed. And in sequence from big dirt to small dirt.


There's a screen in the well to keep rocks out of the pump.

I have faucets for garden/lawn water. Dirty water won't hurt the grass. But I have had trouble with sand jamming the faucets. I have a screen, which I can flush-off and re-use "forever". I take garden water from that. I flush the sand to the yard.

The water is still brown. Mostly Iron Oxides and related material. It looks bad in bathtub or drinking glass. I have a big paper/plastic filter which takes most of that out. This fills with mud and has to be thrown-out. Not putting garden water through it reduces the filter replacement rate.

This well was neglected for decades. While we can get a "safe" test result after shock chlorination, we are not 100% sure it is germ-free. So we had a UV germ killer *just* for drinking water. This is a very small slow thing, would take all day to fill a bathtub.

So just enough filtering for what the water is for.

Underneath I show a 3-stage amplifier with weak-signal and big-signal stages. The big power stage eats slightly filtered DC. The small stages get added filtering.

Your LED will light-up fine with any kind of crappy DC. As Jack says, don't filter its power (but you might polarity-protect, like I screen the sand from my garden water). The reduced load of the rest of the pedal may allow better filtering in less size/cost.

Electronic current always flows in LOOPS. We try to forget this, but things don't work if the loops aren't working. Water supply is the same, almost. All our water goes up to the clouds and down in the earth over and over. We don't have to lay pipes. But if we do, we have to keep the loop flowing. (There is a little difference because a filter can store a handful of mud. But if that trash can fills up the mud will back up in the filter because I can't throw it out.)

So I drew all the loops. The well-rocks fall back to ground. I flush the sand-screen to the lawn, to earth. The paper/plastic filters can't be cleaned- I knock the cruft off and regretfully send them to land-fill. The UV "filter" doesn't actually remove germs, they pass (dead) through us and back to ground.

[amz-fx]

6 Reasons Guitar Pedals Pop When Switched

..and some of them are very hard to prevent. The only totally popless solution that I have tried is jfet switching, as in Boss pedals.

regards, Jack

[Rob Strand]

6 Reasons Guitar Pedals Pop When Switched

Good summary.

..and some of them are very hard to prevent. The only totally popless solution that I have tried is jfet switching, as in Boss pedals.

Yes, you can't beat the cross-fading action.