[ARC5] Power Supply Filter Question

[Mike Feher]

The way I remember it, it was effectively a capacitance multiplier by the
beta of the transistor. - Mike 

Mike B. Feher, N4FS
89 Arnold Blvd.
Howell, NJ, 07731
732-886-5960 


-----Original Message-----
From: J. Forster [mailto:jfor at quikus.com] 
Sent: Sunday, December 22, 2013 2:37 PM
To: Mike Feher
Cc: 'Ben Hall'; arc5 at mailman.qth.net
Subject: RE: [ARC5] Power Supply Filter Question

Similar, but not really the same.

The Miller effect is due to capacitive feedback from plate-to-grid. The
plate has to move in voltage or it doesn't work.

The Beta-C basically uses a current amplifier to amplify the
filtered/regulate voltage across the capacitor/zener.

-John

=================






> If I remember right, this is known as the Miller effect. - Mike
>
> Mike B. Feher, N4FS
> 89 Arnold Blvd.
> Howell, NJ, 07731
> 732-886-5960
>
> -----Original Message-----
> From: arc5-bounces at mailman.qth.net 
> [mailto:arc5-bounces at mailman.qth.net]
> On
> Behalf Of J. Forster
> Sent: Sunday, December 22, 2013 2:09 PM
> To: Ben Hall
> Cc: arc5 at mailman.qth.net
> Subject: Re: [ARC5] Power Supply Filter Question
>
> It's basically an emitter follower.
>
> The pass traqnsistor's collector goes to the supply; the emitter to 
> the load.
>
> One version uses a resistor between coll. and base & a capaciytor to 
> ground.
> This filters ripple, but does not regulate. It effective capacitance 
> is roughly beta x cap value.
>
> Another version uses the same resistor position, and one or more 
> zeners in place of the cap. This regulates the output voltage.
>
> -John
>
> ===============
>
>
>
>
>
>> Hi John and list,
>>
>> Sounds very interesting.  Where can I find information on the Beta-C 
>> filter?
>>
>> On 12/21/2013 7:37 PM, J. Forster wrote:
>>> A Beta-C filter is relative simple and more than adequate. With a 
>>> couple of protective diodes, it's just about bulletproof. The 
>>> version with a Zener will easily add sufficient regulation.
>>
>> thanks,
>> ben
>>
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