A few more effect questions

[cream123]

What pots (linear vs. audio) are normally used for effects if it's not noted? this one says 1M-log gain.

Artie, I know you answered this already but doesn't Vref means Voltage reference point?

What are the parts of (J)fets?

Last but not least, what does drain biased mean?

Thanks
-Marc

 

[cream123]

Re: A few more effect questions

A few more

I see all of these resistors on the bottoms of the circuits. One end of the resistors is grounded and the other is hooked up to the rest of the effect. The same is with a few capacitors. What do these do with the circuit? Just lower the voltage to get it to a ground level? I think I may have just answered my own question.


What does a polarized cap do for a circuit? These are two 100 micro-farad polarized capacitors located on the top of the circuit.

I know this is a bit complicated but I do want to do this pedal. Not boosters and what not. My goal is to get this pedal done. Then I'll feel like I've actually accomplished something. Again, I just want to get this done. Even if it means spending a lot of time just pounding out how everything works; and it probably will. I've got too much time on my hands anyway. (cue styx)

 

[Robert Delahunt]

Re: A few more effect questions

Uh, as for linear versus audio taper pots, log means logarhythmic (sp?), and I would assume that audio taper is log taper, since linear taper is a perfect equal amount from 1 to 10.

 

[cream123]

Re: A few more effect questions

Uh, as for linear versus audio taper pots, log means logarhythmic (sp?), and I would assume that audio taper is log taper, since linear taper is a perfect equal amount from 1 to 10.

Well it's a good thing I know what I'm talking about then. :laugh2:

 

[Rich_T]

Re: A few more effect questions

Yeah, you dont want them log pots, they will have a useable range of basically zero.

 

[Artie]

Re: A few more effect questions

I see all of these resistors on the bottoms of the circuits. One end of the resistors is grounded and the other is hooked up to the rest of the effect. The same is with a few capacitors. What do these do with the circuit? Just lower the voltage to get it to a ground level? I think I may have just answered my own question.

The resistors form a voltage divider with the one thats above it in the circuit. Thats how they set the bias points of the transistors. The caps either block or pass certain frequency ranges. You want the "audio" to pass through. You want RF noise suppressed.

What does a polarized cap do for a circuit? These are two 100 micro-farad polarized capacitors located on the top of the circuit.

They take some of the "pulse" load off of the battery. Audio is a dynamic signal. They supply current for the brief moments when you slam a chord. They recharge on the softer notes.

I know this is a bit complicated but I do want to do this pedal. Not boosters and what not. My goal is to get this pedal done.

Cool, but remember, you can build the pedal without knowing the electronics. Someone else has already designed it. Just don't change anything.

Artie

 

[Artie]

Re: A few more effect questions

What pots (linear vs. audio) are normally used for effects if it's not noted? this one says 1M-log gain.

There is no "normal" in this case. It just depends on how the circuit was designed.

Artie, I know you answered this already but doesn't Vref means Voltage reference point?

An audio signal needs to extend above and below a reference point. In most line-powered applications, that reference would be "ground". In a battery operated, or single-ended supply circuit, you need to set a 1/2V reference. (In this case, 4.5 volts determined by those two 10k resistors.) Since the signal now "floats" at 4.5 volts, you need that output cap to trim off the DC.

What are the parts of (J)fets?

Gate, Drain, and Source.

Last but not least, what does drain biased mean?

They've use a pair of resistors to set a DC voltage on the Drain. Its just how it works.

 

[cream123]

Re: A few more effect questions

The resistors form a voltage divider with the one thats above it in the circuit. Thats how they set the bias points of the transistors. The caps either block or pass certain frequency ranges. You want the "audio" to pass through. You want RF noise suppressed.



They take some of the "pulse" load off of the battery. Audio is a dynamic signal. They supply current for the brief moments when you slam a chord. They recharge on the softer notes.



Cool, but remember, you can build the pedal without knowing the electronics. Someone else has already designed it. Just don't change anything.

Artie

Thanks for the help!

 

[Artie]

Re: A few more effect questions

You're welcome. Good luck on this project.

 

[cream123]

Re: A few more effect questions

One more question: What tolerance and wattage of resistors are to be used?

 

[cream123]

Re: A few more effect questions

Where can I find capacitors with n-farads?

 

[GuitarStv]

Re: A few more effect questions

Yeah, you dont want them log pots, they will have a useable range of basically zero.

That's not entirely true . . . if you're using the knob to control an effect parameter (like say, number of delay repeats) then you would want a regular linear taper pot. If you have a knob controlling the volume of the effect then you would probably want a logarithmic taper. The human ear doesn't hear linearly, it hears differences in volume logarithmically. When you adjust volume with a linear pot it sounds like it's doing almost nothing at all untill you get about half way or so . . . then it sounds way too loud. A logarithmic pot sounds smooth as you're adjusting the volume from quiet to loud. That's why log taper is also called audio taper.