[sdiy] varactor/varicaps?

[Steve Carter]

They were used a lot in 70s/80s TV sets for voltage controlled push button tuning. These were smaller values being for VHF and UHF use. There is a 500pf Varicap intended for AM bands which is the BB112 - it comes in a TO92 type package.  I've often wondered too whether these can be put to synth use, maybe even used in a capacitance multiplier configuration to become useful in the audio range. 

Steve 

On 18 Nov 2010, at 20:40, dan snazelle wrote:

> anybody know much about varicaps? they sound too good to be true...voltage variable capacitance up to 200pf?
> 
> 
> of course a lot of them come in weird form-factors (sot-23,etc)
> 
> anyway, wondered why i never see them in any projects.
> 
> thanks
>