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ZP Delays

Started by GrindCustoms, July 15, 2014, 07:31:46 PM

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GrindCustoms

Yo! I'm putting together 2 of Brian's ZP delays, SDX and DD.

BOM asks for BC550, wich variant would be the best to use, A, B or C?

Also, anyone up for doing a little resume about the purpose of those transistors? :D

Thanks

Rej
Killing Unicorns, day after day...

Building a better world brick by brick:https://rebrickable.com/users/GrindingBricks/mocs/

midwayfair

They're a current mirror.

http://en.wikipedia.org/wiki/Current_mirror#Basic_BJT_current_mirror

You can use literally any NPN there and they'll do their job, but you probably want them to be the same part because the gains will be more closely matched (which is better but hardly necessary for proper operation); and the BC5xx transistors are pretty consistent, which I'm guessing is the reason for the 550 being specified.

GrindCustoms

Quote from: midwayfair on July 15, 2014, 07:47:34 PM
They're a current mirror.

http://en.wikipedia.org/wiki/Current_mirror#Basic_BJT_current_mirror

You can use literally any NPN there and they'll do their job, but you probably want them to be the same part because the gains will be more closely matched (which is better but hardly necessary for proper operation); and the BC5xx transistors are pretty consistent, which I'm guessing is the reason for the 550 being specified.

Cool! Thanks Jon :)
Killing Unicorns, day after day...

Building a better world brick by brick:https://rebrickable.com/users/GrindingBricks/mocs/