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Anyone consider this as an alternative?

Hi
I read an old electronics book where resonance chokes where sugested as a soulution for this dilemma.
Not just the regular resonance choke design, but to use a regular PSU transformer in 1:20 ratio (aprox. 110V:6V in US or 230V:12V in EU)
The secondary (6V or 12V) is used in the amplifier filter for really low DC resistance (aprox. 1-2Ω).
The primary (110V or 230V) is connected as a resonance circuit with a cap in paralell with the primary winding (The resonance freq. in found where L and C reaktance is equal. (L- and C-resistance neglected).
The book sugested a futher adjustable cap in parallel for fine adjustment of the resonance peak to 2 x mains freq = 120Hz(US) or 100Hz(EU) .
This could also be done in another way (-cheaper), by connecting a potentiometer i series with the fixed cap.
This is because the resonance freq. is actually where the Impedance of the L and C, so by adding a variable resistance to the C-leg of the resonance circuit, the Q-value vill vary somewhat, but most, the resonance freq. vill be adjustable.

Remember:

The DC current trough the secondary is only going through small amount of wire-turns, which make a regular x-former ok without an airgapped core.

The impedance will be reduced from primary to secondary side, but as the circuit is a resonance peak, the impedance is really high at 120Hz(US) or 100(EU).
The

The circuit has only a high impedance at a very narrow band (easy to calc. by using the Q-value), so perhapps a second fiterstage (smaller hi mu choke) should be used to eliminate hi freq. ripple.

I hope I made myself understud..
I just would like to hear your comments about it as an alternative to the one sugested in the tread.

Regards
Pix ;-)
Sweden

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  • Anyone consider this as an alternative? - ahlgren11@telia.com 13:19:28 05/06/07 (0)
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