Help with wien bridge diagram

Thread Starter

hadoque

Joined Jul 24, 2007
10
Hi
I'm very new to electronics, and I thought a fitting first project would be a Wien-bridge oscillator. Since I have a lm386 amplifier lying around, I thought I'd use the circuit discribed in the datasheet of this component (attached, see page 5). Now I have some questions about this diagram.
What kind of component is the round thing marked "ELDEMA CF-S-2158"?
What is \(R_{L}\), \(V_{S}\) and \(V_{O}\)?
What is the "Bypass"? What voltage should I use and where do i connect the output (speaker or whatever)?

Many thanks for help with answering these probably simple questions.
 

hgmjr

Joined Jan 28, 2005
9,029
Hi
I'm very new to electronics, and I thought a fitting first project would be a Wien-bridge oscillator. Since I have a lm386 amplifier lying around, I thought I'd use the circuit discribed in the datasheet of this component (attached, see page 5). Now I have some questions about this diagram.
What kind of component is the round thing marked "ELDEMA CF-S-2158"?
What is \(R_{L}\), \(V_{S}\) and \(V_{O}\)?
What is the "Bypass"? What voltage should I use and where do i connect the output (speaker or whatever)?

Many thanks for help with answering these probably simple questions.
The round thing is a light bulb. It is used in this application because it exihibits negative resistance.

Vs is the positive power supply input.

Vo is the output of the oscillator.

hgmjr
 

Thread Starter

hadoque

Joined Jul 24, 2007
10
ok, thanks
what kind of bulb can I use? The specified bulb seems to be hard to get, aswell as any bulb with the 3V 15mA specs. Can I use a bulb with higher voltage or higher current?
 

beenthere

Joined Apr 20, 2004
15,819
Mouser carries lamps and has no minimum order. It is possible to substitute bulbs with different ratings by experiment. The filament voltage should be no more than about 15, and the rated current should be no more than 40 ma. You just have to find a resistor for the feedback that works with the bulb, using more current - smaller resistor as the basis.
 

Thread Starter

hadoque

Joined Jul 24, 2007
10
I live in Sweden, so I'd rather not order from the US. I found 3V 10mA bulb in sweden though, do you think that might work?
 

DanRilley

Joined Jan 13, 2008
107
This post is real old but maybe the poster still reads. Where do you buy bulbs from in Sweden? I'm also here and looking to complete the same project.
 
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