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Replacement for BC558A and BC548B

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New Member
They are used in an EMS (electronic muscle stimulating) machine, close to the 9V supply. I burned a couple of them when i short circuited while in full power. Don;t have the scematic as you can assume.

Any ideas of replacements that can stand higher current but still protecting the rest of the circuit?

hope anyone can help. Ideally with a schematic.


Their selection by the manufacture would have been based on the operating parameters of the circuit...they are fit for the job........

replace them with the same device, and then leave it alone, dont mess with the circuit........ :lol:


New Member
i have an idea, stop shorting it!!!!
the transistor you are talkimng about is 100mA if i am not mistaking, so maybe they are there so that no more than 100mA pass trough the circuit. i think that you shouldnt replace them with highter power because you might get fried!!!


New Member
Thank you people,
i am planning to replace them with the samw ones but the problem is that i am not sure if they are the ones i told you about.
It;s a guess looking at the nearby transistors.

Anyway i am waiting an answer from the manufacturer.

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