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Oscillator/frequenct question

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ddreier

New Member
Hello, just found the forum, which is great because I've got a question about an oscillator.

I want to build the "simple" oscillator featured here (Figure 1). The only problem is that the schematic does not include the values for "RT" and "CT".

So what I'm wondering is if anyone could suggest values for these so that I could generate at least 1 kHz and whatever other frequencies around that.

Thanks!
 
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audioguru

Well-Known Member
Most Helpful Member
I've got a question about an oscillator.

I want to build the "simple" oscillator featured here (Figure 1). The only problem is that the schematic does not include the values for "RT" and "CT".
It has two frequency ranges as shown in the spec's at the end of the article. The RT and CT formula is also there.
 

ddreier

New Member
Ok, so then in the formula he gives, f=1/(2*pi*R*C), R is RT and C is CT for both times that they show up in that schematic?
 

audioguru

Well-Known Member
Most Helpful Member
Ok, so then in the formula he gives, f=1/(2*pi*R*C), R is RT and C is CT for both times that they show up in that schematic?
Yes.
Both C's are the same value and since the pots are ganged then the R's are also the same value.
 

ddreier

New Member
Ok, thanks!

Oops, one more question: I'm assuming that R is in Ohms, but what about C? I suppose it is in Farads?
 
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Roff

Well-Known Member
The first two stages are commonly called all-pass filters. Google can find more information if you are interested.
 

ddreier

New Member
All I'm trying to figure out right now is what values I need for RT and CT. And if my assumptions are correct about F=(2*pi*R*C), I have found them.

But I would still like to know for sure if R is in Ohms and C is in Farads.
 

Roff

Well-Known Member
All I'm trying to figure out right now is what values I need for RT and CT. And if my assumptions are correct about F=(2*pi*R*C), I have found them.

But I would still like to know for sure if R is in Ohms and C is in Farads.
Yes, R is in Ohms and C is in Farads.
 

ddreier

New Member
Okay, one more question, do I need two seperate Pots and caps for RT and CT since there are two in the schematic, or do I just use one physical connected to both pins?
 

audioguru

Well-Known Member
Most Helpful Member
The dotted line between the two pots shows that they are ganged together with a single knob. Each pot has the same adjusted resistance.
 
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