[Boatanchors] Theory Question

[rbethman]

Keith,

Remember that capacitors in parallel, are calculated the same as 
resistors in series.

The two you used as an example:  .01 and .001  becomes a capacitance of 
.011.

Depending on where in a circuit, the instance you gave as "bypass", will 
change the resonance.

It indeed may not be much, but it can be a good bit more effect than we 
think.

One old tube type radio was modified in the tuning section by 
paralleling one 10pf across an air variable.  It dropped the lowest 
frequency of the tuning section from 2Mc to 1.660Mc.

Sometimes we have to step back and consider how the resonance is altered.

It may appear as making no sense, yet it has a bit more impact than we 
think, until we look at the circuit in its entirety.

Regards, Bob - N0DGN


On 7/29/2015 10:55 AM, Keith Densmore wrote:
> Have a question I know someone will know the answer to.
> Very often in tube bypass capacitors, both b+ and cathode, two caps are used, a
> lower value and a higher value, ie .01 and a .001.
> What is the purpose of this, would not the .01 do the job alone? Never seen
> this addressed.
>
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> Thanks,
> Keith ve3ts