[Amps] Led display problem

[Ian White G3SEK]

Steve Thompson wrote:
>On Tuesday 19 April 2005 08:51, G3rzp at aol.com wrote:
>> In a message dated 18/04/2005 22:31:16 GMT Standard Time, pegloff at gmail.com
>> writes:
>>
>> But a  bit more difficult to measure the other currents and voltages for
>> which  the reference et the cathode level.
>>
>> Has anyone an idea how to do that,  on a simple way ?
>Opto isolators? Some have a reasonable linear range, or you can use a second
>one and an opamp to correct any non-linearities.

Maxim make a range of current monitoring ICs for exactly this kind of 
purpose. The two input terminals are connected by a low-value shunt 
resistor, and can 'float' up to about 30V. Output is a voltage directly 
proportional to the current, referenced to ground.

However, I agree with most others here, that a bargraph with only 10 
LEDs is generally not the best way to monitor an amplifier - they can 
hide useful information that a meter needle will show.

>With any of the suggested
>solutions, you'll need to take care to protect the monitoring circuit under
>fault conditions.

Details are on Rich's website, and in the Triode Board manual which is 
downloadable from my site:
www.ifwtech.co.uk/g3sek/boards

-- 
73 from Ian G3SEK