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Steiner VCF mod for self-osc

Steiner VCF mod for self-osc

2013-03-20 by Steve Inselman

Hello Ken,
Which resistor should I change to achieve self-osc in the Steiner filter?
I used the 2N2222 + 2N907 transistors.
Thanks,
Steve


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Re: Steiner VCF mod for self-osc

2013-03-20 by cg_synth

It's in the notes on the page.

>When using 2N3904 and 2N3906 I had to tweak the 2k2 in the resonance part
of the circuit (connected to the emitter of the NPN in the amplifier) to
compensate for transistor gain. A 15k across it brought it to the point
where with the resonance full up, it was slightly ringing. A signal on the
HP or LP inputs would then send it onto full oscillation, requiring the
resonance to be backed right off to stop it, which is normal behavior for
this design.

Ken

>Hello Ken,
> Which resistor should I change to achieve self-osc in the Steiner filter?
>I used the 2N2222 + 2N907 transistors.
>Thanks,
>Steve
>
>
>[Non-text portions of this message have been removed]
>
>
>
>------------------------------------
>
>The CGS Modular Synth home page: http://www.cgs.synth.net/
>Yahoo! Groups Links
>
>
>
>
_______________________________________________________________________
Ken Stone sasami@... otherunicorn@...
Modular Synth PCBs for sale <http://www.cgs.synth.net/>
Australian Miniature Horses & Ponies <http://www.blaze.net.au/~sasami/>

Re: Steiner VCF mod for self-osc

2013-03-20 by Steve Inselman

Okay, I just assumed that it only applied when using 2N3904 and 2N3906 transistors.
Thanks again Ken,
Steve




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From: "sasami@..." <sasami@...>
To: cgs_synth@yahoogroups.com
Sent: Wednesday, March 20, 2013 7:32 PM
Subject: Re: [cgs_synth] Steiner VCF mod for self-osc



It's in the notes on the page.

>When using 2N3904 and 2N3906 I had to tweak the 2k2 in the resonance part
of the circuit (connected to the emitter of the NPN in the amplifier) to
compensate for transistor gain. A 15k across it brought it to the point
where with the resonance full up, it was slightly ringing. A signal on the
HP or LP inputs would then send it onto full oscillation, requiring the
resonance to be backed right off to stop it, which is normal behavior for
this design.

Ken

>Hello Ken,
> Which resistor should I change to achieve self-osc in the Steiner filter?
>I used the 2N2222 + 2N907 transistors.
>Thanks,
>Steve
>
>
>[Non-text portions of this message have been removed]
>
>
>
>------------------------------------
>
>The CGS Modular Synth home page: http://www.cgs.synth.net/
>Yahoo! Groups Links
>
>
>
>
__________________________________________________________
Ken Stone sasami@... otherunicorn@...
Modular Synth PCBs for sale <http://www.cgs.synth.net/>
Australian Miniature Horses & Ponies <http://www.blaze.net.au/~sasami/>




[Non-text portions of this message have been removed]

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