Variable capacitor circuits

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walters said:
varactor diodes the capacitances are in the picofarads

Can i use Varactors in "series" to increase the capacitances?
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Of course not! The value is less when capacitors are in series.

Or i would need a "Custom" Varactor diode to have the capacitance in the microfarads?
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Ridiculous.

What would the Varactors doping process do different and how? the PN junction needs to be Bigger?
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Not possible.


I need a Varactor is the Mircofarads? which ones is there please?
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Not available.
 
walters said:
I still don't get have PWM can make a (pf) Varactors into a (uf) varactors?
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You will be taught how PWM works when you learn something about electronics.
 
walters said:
PWM have duty cycle which changes the time constant of the Varactor capacitance
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No. PWM has a duty-cycle that changes the value of any capacitor.
Varactor diodes use a DC voltage or modulated DC voltage to change their tiny value, not PWM.
The tiny value of varactor diodes is useful only in radio circuits. I thought you are working with audio circuits using capacitor values that are thousands of times greater than varactor diodes.
So forget about varactor diodes for your circuit.
 
You can use them in parallel.

Or i would need a "Custom" Varactor diode to have the capacitance in the microfarads?
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Ridiculous.
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microfarads??? :shock:
omg!
That means you will need at least 100,000 diodes in parallel that can produce a 10pF capacitance! By the time you inserted the 100,000th diode, you would probably have ran to us again :lol:

I need a Varactor in the Mircofarads? which ones is there please?
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Not available.
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Thats it. and Walters, WHY would you need a varactor in Microfarads?

Why not increase the resistors that also affect the frequency you are dealing with so that you can lower the capacitance? Increasing resistors can help reduce power requirements and potentially extend battery life.
 
mstechca said:
Why not increase the resistors that also affect the frequency you are dealing with so that you can lower the capacitance? Increasing resistors can help reduce power requirements and potentially extend battery life.
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Brilliant! Really.
I am glad to see that you have learned a lot and truly understand these things. :lol: :lol:
 

At the risk of taking his side, it doesn't help when the entire thread is pointless and confusing! :?

Still, as they say, "a little knowledge is a dangerous thing!".
 
Brilliant! Really.
I am glad to see that you have learned a lot and truly understand these things. :lol: :lol:
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I knew that well before you even said BOO to me :lol: :wink:

At the risk of taking his side, it doesn't help when the entire thread is pointless and confusing! :?
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Unless Walters has a definite goal in mind, I can see this thread entering more confusion.
 

Unless that is the goal
 
Walters is confused because he wants to make electronic wah, wah sound effects mechanically in his 50 year old Leslie rotating speaker, by modulating its speed with exotic waveforms.
I think he also wants to make the Leslie speaker's sound electronically.
He also wants to fix his worn out 50 year old wah, wha pedal, but its special pot isn't available so he wants to convert an ordinary pot.

It would be confusing to a nooby and to an engineer to analyse the rotating phase shifts and Doppler FM effects of a Leslie speaker, then try to make the same sound and new ones with opamp variable allpass filter circuits.
If I had a guitar then I would also try to make the sound electronically, but I would probably use DSP instead of millions of opamps.

It boggles the mind, doesn't it? :lol:
 
Nigel Goodwin said:
you can buy DSP based effects for very little money these days!.
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I like to hear those words and didn't know that. I think Dr. EM and myself would like to look at (hear?) some. Please post a link.

Walters probably won't be able to get them for 50 years.
 

Almost any modern modern effects pedal, particularly the multi-effect ones. My daughter had this one for Christmas 2004
 
Samson's A2 effects pedal has millions of features but no price. I'll Google around to find out its price.
 
Walters is confused because he wants to make electronic wah, wah sound effects mechanically in his 50 year old Leslie rotating speaker, by modulating its speed with exotic waveforms.
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I like your use of the word "exotic" :lol: you make it sound like his waveforms are so interesting, you just want to elaborate on them. (because they are exotic)

50 years old :shock:
No offense Walters, but I think the whole arrangement should be thrown in the garbage. Why not buy a set of walkie talkies, and make wah-wah sound effects into them? In fact, get some tape, and wrap tape around one walkie talkie until the transmit button is held down by the tape. Then smash that walkie talkie into pieces, and maybe you will get extraordinary waveforms :wink:

I think he also wants to make the Leslie speaker's sound electronically.
He also wants to fix his worn out 50 year old wah, wha pedal, but its special pot isn't available so he wants to convert an ordinary pot.
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Throw the walkie talkie I was talking about at the working leslie speaker. I wonder how exotic the sound effects will be in the receiver :lol:

Thats why I say throw the whole thing out!

It boggles the mind, doesn't it?
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Walter's ideas boggle my mind.
 
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