[Amps] Don't do this

[Ian White GM3SEK]

Carl wrote:
>
>
>Ian, do you have any references to those diodes NOT protecting a 
>SB-200/220 meter?  I certainly dont and have seen many failed 1N400x 
>diodes that saved the meter. Redesigining the Heath circuits is not an 
>option to most users.
>
Granted - for those particular meters in that particular amplifier.

Carl and I are approaching the problem from two different directions. He 
repairs many examples of the same models with the same faults, so he 
builds up a wide database of experience. But my boards sell mostly to 
individual constructors - every amp is different, and the only way I can 
cover that wide range of unknown situations is to aim for the maximum 
possible protection.

The "0.5V full scale" idea can do that. Bill's method using a series 
resistor is the simplest, while mine will work with a wider range of 
meters.


-- 

73 from Ian GM3SEK
http://www.ifwtech.co.uk/g3sek/boards