Why Couldn't This Be Used For True Bypass?

Harry · February 16, 2006, 01:09:15 AM

Or could it?

gez · February 16, 2006, 03:02:03 AM

Because the diode will create crossover distortion in every effect you built using this.

Edit: plus halfwave rectify everything...

Harry · February 16, 2006, 11:15:56 AM

Anyone care to elaberate. Is it because a guitar signal is AC? What if you were to halfwave rectify the signal before and then reverse the process after (Is it possible to reverse rectify it?). Sorry if this is very beginnerish, but I've never taken an electronics class.
Electrons

theblueark · February 16, 2006, 12:19:18 PM

The signal goes back and forth. In this circuit it can only go forth and not back. Thus half of it is gone.

gez · February 16, 2006, 01:11:54 PM

Exactly, plus the signal needs to meet the threshold of the diode before you hear anything, so everything until then isn't heard - you slice the bottom off your half-wave rectified signal!

Harry · February 16, 2006, 01:24:46 PM

Okay, so that all makes sense. What about the rectify de-rectify idea? Like, converting the guitar signal to dc then back to ac later on (I guess it'd involve transformers). I know this wouldn't be practical for this switching usage, I'm just trying to understand how you could use diodes in guitar effects.

gez · February 16, 2006, 01:29:58 PM

Difficult enough to 'de-rectify' a waveform where it's just a test signal and you know the exact frequency, imagine the headache with an actual signal!

Harry · February 16, 2006, 01:58:06 PM

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Well OK then how bout using transformers to go from ac-dc-ac?
I've been looking all over the internet for this stuff without much luck.
There has to be some way to limit the direction of a guitar signal right?

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gez · February 16, 2006, 02:37:11 PM

QuoteWell OK then how bout using transformers to go from ac-dc-ac?
I've been looking all over the internet for this stuff without much luck.

Don't really understand. A signal can ride on the back of a DC bias - this is how most amps work - and capacitors block DC either side (input and output)...is this what you mean by going 'from ac-dc-ac'? If so, yes transformers have been used to couple/isolate stages.

QuoteThere has to be some way to limit the direction of a guitar signal right?

Yes, you've shown it - use a diode. If you want to get flashy and want more accurate rectification, google ideal rectifier/ideal diode...or use the search.

Harry · February 16, 2006, 03:21:36 PM

Sorry if my questions a poorly posed, like I said before I'm still trying to learn this stuff. I apologize for my ignorance.

QuoteYes, you've shown it - use a diode.

Without rectifying it though.

QuoteWell OK then how bout using transformers to go from ac-dc-ac?

I was thinking that maybe if I converted the signal to DC (Is this possible) then send it through the diode and then convert the DC signal back to AC.

gez · February 16, 2006, 03:37:47 PM

Quote from: Harry on February 16, 2006, 03:21:36 PM
Sorry if my questions a poorly posed, like I said before I'm still trying to learn this stuff. I apologize for my ignorance.

Not a problem, the forum is here to ask questions.

QuoteI was thinking that maybe if I converted the signal to DC (Is this possible) then send it through the diode and then convert the DC signal back to AC.

OK, you've lost me a little. Why do you want to do this? If it's for bypass forget what you posted - or any idea remotely similar - as it's just not going to work and is pointless considering the cost of a DPDT switch.

If you want to experiment with half-wave rectification, great... then google the phrases I quoted in my last post.

Harry · February 16, 2006, 04:00:23 PM

QuoteOK, you've lost me a little. Why do you want to do this? If it's for bypass forget what you posted - or any idea remotely similar - as it's just not going to work and is pointless considering the cost of a DPDT switch.

QuoteI know this wouldn't be practical for this switching usage, I'm just trying to understand how you could use diodes in guitar effects.

Actually after thinking about this for a while I don't think I'm going to need this. Thanks for your help, though.

scaesic · February 16, 2006, 04:16:23 PM

signal can't be sent in d.c format. (unless you use digital, and i'm assuming you're a long way off from that)

Harry · February 16, 2006, 04:48:19 PM

O.K. Thanks that's nice to know

gez · February 16, 2006, 04:53:54 PM

Quote from: Harry on February 16, 2006, 04:00:23 PM
QuoteOK, you've lost me a little. Why do you want to do this? If it's for bypass forget what you posted - or any idea remotely similar - as it's just not going to work and is pointless considering the cost of a DPDT switch.
QuoteI know this wouldn't be practical for this switching usage, I'm just trying to understand how you could use diodes in guitar effects.
Actually after thinking about this for a while I don't think I'm going to need this. Thanks for your help, though.

Sorry Harry, didn't see that. Diodes tend to get used in clipping circuits. They can also be used in the signal path, along the lines of what you drew up, in order to create distortion, though this will be harsher (crossover).

Diodes are also used for half or full-wave rectifying a signal. This creates octave effects and distortion. Plenty in the archives about all these circuits.

PS Please don't feel put off posting questions, that's how you learn.

Harry · February 16, 2006, 06:37:11 PM

QuoteDiodes are also used for half or full-wave rectifying a signal. This creates octave effects and distortion. Plenty in the archives about all these circuits.

Yeah, after all that talk about rectifing I rectified me up a halfwave distortion. It's pretty interesting, definately something worth considering in a home brewed distortion.

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Why Couldn't This Be Used For True Bypass?