switch for stombox!!!

[rx5]

MY hometown (Tacloban City) really SUCKS!!!!!!
:evil:  :evil:  :evil:  :evil:  :!:  :!:  :x  :x

cant seem to find a push button DPDT switch for the FX "on-off"... that would surely make life easier ...... :cry:  :evil:

btw, anyone here tried CMOS siwtching?? i used 4017 for "+"  input , not like the CD4013 which uses "gnd" to change state..you had to release the foot switch before it changes state....

then I used CD4053....problem is i hear "POPS" whenever switching take place.... I biased the inputs to half the power supply then caps for the input output....

what would be the best solution here??

does CD4066 "pop" too..??

tnx for any info.... :cry:  :?

[Mike Burgundy]

switching electronically often pops if not carefully designed. GEO has some switching stuff up, I think (link is on the top of your screen). One of the tricks is to get the switching ramps to be softer. Not a real hard instantaneous 0 to 1, but a slight slope. If you switch CMOS ort other electronic relays with a mechanical switch, the contacts may bounce which will also make for nasty noises.  
Also, it's real easy to order from smallbear (www.smallbearelec.com), and get real heavy duty Carlings or 3PDT Fulltones and be done with it. Steve ships all over the world.
hih

[rx5]

that would be nice considering if you order parts by bulk.... but what if 3 pcs only.... shipping costs are always the problem..... they cost more than the parts you order..... thanks anyway..ill try putting a high value cap at the output of CD4017....say 100uF to make the transition slower.. :wink:

[Nasse]

I may be wrong my knowledge about this is somewhat rusty but I remeber havin read that common CMOS switches "click" can not fully removed by slowing control voltage. JFET switching benefits this trick but has its drawbacks. I must read that Geofex info before I say too much.

[Mike Burgundy]

I think the Phillipines will be just $4 shipping for 3 switches (at $9 a pop, which is a good price).
Just pointing that out

[rx5]

maybe it "pops" if CD4053.... ive tried wiring a CD4066 chip for switching but forgot if they "popped or not" ....done it 3 years ago... :shock:

and through trial/error I got rid of the ref voltage(1/2 power supply) to the in/out pins and noticed the "pops" were REALLY minimized??!! i dunno why but thats how my project came out...used it to switch a flanger circuit...by the way, just used it as as a SPDT... switching the output iether from the fx output or from the signal input...i dunno if it would still "pop" if wired as true bypass... :lol:

for the DPDT mechanical switches?? hmmmm.... :?  maybe ill reconsider... if "popS" cant really be rid from CMOS switchers.... they would certainly make switching audio a lot more easier...

cya :wink:

[R.G.]

CMOS switches cannot be completely prevented from popping.

Neither can any other non-optically coupled electronic switch. What you can do is make the switching transient inaudible. That is quite possible.

Whenever you switch a CMOS device (or a JFET, or a bipolar, or a relay for that matter) the unwanted small capacitances in the device couple the switching voltage into the audio-conducting electrodes.  Whether this is a huge pop or an inaudible one depends on how well you do the design.

In CMOS particularly, there are two devices being switched at the same time. The control voltages are equal and opposite, so if the DC condition at the audio channel is in the middle of the power supply, the transients tend to cancel each other out. Hence the advice to bias them in the middle of the power supply.

Switching a high impedance audio line makes it worse; if you have a 1M input to the amp and couple in 25 picocoulombs ( a not-unreasonable figure) you'll get a pop. Shunt the amp with 10K and you get no audible pop.  Impedances matter. 100K and biasing in the center has worked for every brand of CD4053 I've tried, although they do vary and some are substantially pop free up to 1M.

The business of slowing down the switching works with all of the technologies. The idea is that if the voltage transition on the control element is slow enough, the tiny coupling capacitances will not be able to couple the slow moving voltage. Works great on JFETs, which are high impedance voltage mode devices. Works so so on CMOS, particularly Craig Anderton's 4016 circuit, where you have the control line go directly to the N-channel device. Unfortunately, the P channel device is driven by an internal inverter, so no matter how slowly you drive it, the P-channel device can still inject charge.

On relays, slowing down the coil voltage change works GREAT. I have several circuits at GEO to show how to do this.

Opto coupled things are in theory free of control line coupling. LED/LDRs work (but are expensive and not very good switches).  LED/photo FETs like the H11F1 are good, but don't stop in the middle of the swing for a variable resistor - you'll get distortion on guitar level signals. LED-MOSFET photo-relays hold great promise, but you have to use two MOSFETs to get around the integral diode in MOSFETs and they're quite expensive right now.

It's really all a matter of degree.

[rx5]

thanks for the explaination R.G.    

how about CD4007 chips...ive seen some on the net.... any info on how to use them??

btw: the input of the ultraflanger was 10M shunted to ground and the output was 100K.... would changing the 10M input shunt res to 100K solve my problem <popping> ??

i used 470K for the bias of the inputs and outputs of CD4053...arent they too high to hold those pins to Vref?? how about 100K??