Re: 465/475 Volts/Div range LED swap problem.


Ozan
 

decided to wire one parallel to the 10X LED. I was really trying to minimize
the complexity of this solution. This was the best I could come up with.
See my reply https://groups.io/g/TekScopes/message/179044
A 470-ohm from collector of the Darlington to ground (across the LED+current
limiting resistor) is all you need. No need for ten LEDs in parallel, and it
is not the most robust solution either.
I now see the solution, 10x was just the label, not the number of LEDs. No need for extra transistor, 470-ohm is all you need. Sim might have worked OK but in the proposed solution base of the new NPN is not pulled to ground strongly so noise could couple to the base easily.

Ozan

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