[ARC5] Power Supply Filter Question

[J. Forster]

See:

http://en.wikipedia.org/wiki/Miller_effect

The Miller effect depends on the voltage gain of the amp. In an emitter
follower, there is no voltage gain.

-John

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




> 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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