Grade my bypass/power/input/output stage

[Boner]

So what do people think? This is what I have come up with after a lot of research and reading here.




-U7 is the input jack, TRS, T going stomp switch 2, R to positive battery, S to ground
I used input for power switching, if thats the right terminology

-U8 is output. I've heard its preferred to do the switching here?

-C7 should be 10uF

-BATT1 is a 9V battery. 1 (positive) to ring of input jack, 2 (negative) to DC9V sleave (pin 2) switching point so when nothing is inserted, pin 2 is shorted to pin 3 to compete the connection between battery and the rest of the circuit.

-R32 (100ohm) is to protect against static dischage

-D1 is for power reversal.
so I can use a boss regulated power supply

-The red 'input' and 'output' are for amp, distortion or whathaveyou input and output points.

[amptramp]

It looks like your external power supply is wired in series with the battery.  It should be an either / or choice.

The input and output jacks seem to be unlike anything available.  The electrodes with the 'v' on the end actually contact the tip or ring terminals or ground.  If you have other switch contacts wired to these (and this was very common with telephone jacks used from early days), they are usually shown as switches with dashed lines to show they are ganged but the 'v' always makes contact with the plug - not necessarily what you want.  Remove the extra 'v's' and you would have the correct symbol.

The output jack does not need any complication.

Since LED2 is always on, it does not need C9 or R33.

[Boner]

Thanks for the pointers! Question about the protection diode, should that be in series with the 100ohm resistor? Take out the resistor because the diode could take care of a static discharge?

The input and output jacks seem to be unlike anything available.  The electrodes with the 'v' on the end actually contact the tip or ring terminals or ground.  If you have other switch contacts wired to these (and this was very common with telephone jacks used from early days), they are usually shown as switches with dashed lines to show they are ganged but the 'v' always makes contact with the plug - not necessarily what you want.  Remove the extra 'v's' and you would have the correct symbol.

Yeah thats a very poorly drawn symbol that  I made. I didn't have one for TRS with switching so I had to make my own "art". From the top down its S, Sn, R, Rn, T, Tn.

[antonis]

What's the purpose of dual 220μF & 100nF..??

[amptramp]

What's the purpose of dual 220μF & 100nF..??

An electrolytic capacitor has an impedance that declines as frequency rises up to a point, usually within the audio band where the impedance starts to rise again, making it look like an inductor.  The 100 nF film or ceramic capacitor has a declining impedance with rising frequency into the tens of MHz so the circuitry sees a low power supply impedance at all frequencies of interest.  The parallel inductance and capacitance may form a tuned circuit resonant at some frequency but the ESR (equivalent series resistance) of the electrolytic usually damps that out.

[ElectricDruid]

What's the purpose of dual 220μF & 100nF..??

An electrolytic capacitor has an impedance that declines as frequency rises up to a point, usually within the audio band where the impedance starts to rise again, making it look like an inductor.  The 100 nF film or ceramic capacitor has a declining impedance with rising frequency into the tens of MHz so the circuitry sees a low power supply impedance at all frequencies of interest.  The parallel inductance and capacitance may form a tuned circuit resonant at some frequency but the ESR (equivalent series resistance) of the electrolytic usually damps that out.

I think Antonis meant "why are there two 220uFs and two 100nFs?", not "why is there a 100nF as well as a 220uf?".

And it's a reasonable question - why *are* there two 220uFs and two 100nFs?

[antonis]

Quite right, Tom..!!
(maybe I should underline "dual" or use something like "a pair of"..)

If electros desirable capacitance is 440μF (220//220) look for a single 470μF - same as for 200nF (100//100) & 220nF..

[anotherjim]

Those extra power caps might be distributed on the FX circuit - which is not shown.

It actually looks ok to me. The DC jack is a switched type and looks absolutely standard to me.

I prefer series protection diode before the resistor.

The LED's could actually be very bright with those resistance values unless they are ordinary "standard brightness" types for which I find 6k8 is perfect. I've never yet had to smooth LED switching with caps, but it probably does no harm. High brightness/efficiency LED's need to have much higher series resistance (unless you fancy some cheap laser eye surgery) and really don't need caps to smooth out the switching current pulse. Also, I power the LED circuit from before the power input resistor, which lets the resistor and supply caps smooth out any LED switching noise at source.

[Boner]

Thank you all!

Those pair of 220uF and 100nF caps I saw somewhere and the explanation made sense to me at the time, so I went ahead and ran with it. I honestly do not remember now the purpose. Should I go ahead and ditch the idea and just have one of each?

I do have filtering caps on each of my transistor amplifier stages, as well as buffers. I have a 10ohm resistor and 100uF electrolytic cap going to ground

[antonis]

Those pair of 220uF and 100nF caps I saw somewhere and the explanation made sense to me at the time, so I went ahead and ran with it. I honestly do not remember now the purpose. Should I go ahead and ditch the idea and just have one of each?

Feel free to go ahead with that.. 

Usually, those pair of caps appear before & after voltage regulators (so they aren't pair, strictly speaking) although electro before regulator is (should be) much bigger than the one after it..

100nF single ceramic(disk) cap should be fine (well explained by Ron)..
220μF   //         electro      //     //    //  set according to the ripple voltage of your taste..

As for individual stage filtering caps, it's an overkill (IMHO) which can do no harm.. 

Also, C25/R10, C37/R64 & C38/R68 form deeeeep sub-sonic HPF.. 
(100nF caps should be more than fine, 10nF should also be OK, 1nF should be acceptable..)

Don't know about J201 leakage current so I can't say if 4M7 bias resistors are of proper value..
(possibly they are OK..)

[amptramp]

I believe the paralleled 220 µF capacitors may give less equivalent series resistance than a single capacitor of the same total capacitance.  It may also kill any tendency for the inductive portion of the electrolytic's frequency response from forming an L-C resonant circuit with the 100 nF capacitors.

[ElectricDruid]

I believe the paralleled 220 µF capacitors may give less equivalent series resistance than a single capacitor of the same total capacitance.  It may also kill any tendency for the inductive portion of the electrolytic's frequency response from forming an L-C resonant circuit with the 100 nF capacitors.

I suppose that would make sense. The ESR's would be in parallel, so would follow the rules for parallel resistances (hence halved), whereas the capacitance would add.

[antonis]

Well said Ron & Tom but, guys  , we are talking about few mA power supply..

[ElectricDruid]

Yes indeed. I didn't say that ESR is an important fact in this situation necessarily (I don't see why it is) but just that it's true that paralleling the caps like that would reduce it. I'd never thought of that before (and I have occasionally had cause to need a low-ESR cap).
I don't know anything about anything inductive and never claimed to. I leave that to the wire-winders.

T.

[PRR]

> I do have filtering caps on each of my transistor amplifier stages

Make the R at least 5% to 20% of the load. The filtering action gets much better, and the voltage loss can still be small.

At a glance, for 6.8K drain loads, think 500r to 2K. 2K may be significant voltage loss. But 500r is small loss and 50X better filtering than your 10r.

I don't see why you have a filter cap on your Power LED. It is always on, will never switch while you play. (LEDs are NOT "noisy".)

I'm unsure about how you switch the FX ON LED. With the switch in the low side, closing the switch will send a BIG spike through the LED to ground. Which is maybe what you were trying to avoid? As-is, move the switch to the high end, above the 6.8K dropper. Or if low-side switching is essential, and battery drain not a problem, run power to the LED all the time but short-out the LED for the Off condition. Current is near-constant that way.