About ampilifing the current

Thread Starter


Joined May 17, 2007
:confused: Hi guys,:)

I'm working in project called "Smart nursing", in this project we use microcontroller to control drawers to open in a certain times to remind the concerned people about the time of the medicine and the type.

The microcontroller is sending signal to the drawers at a certain time to open and then another signal for the closing, but unfortunately the output signal which is from the microcontroller is V=5V and I=20 micro A. But the drawers need I = 200mA actually I tried many circuits to solve this problem like Darlington but I can't get the required current. Can any one help me please?.

How can I amplify current from 20micro A up to 200mA?:)


Joined Apr 20, 2004
Use the 5 volt signal from the microprocessor to switch a logic-level FET. Select one that will handle 500 ma @ the desired voltage.

Probably be better advice if we had a circuit to look at.


Joined Jan 22, 2004
can you post the circuit you have made? maybe you have configured it in the wrong way. show us the schem and we can make appropiate suggestions.:)



Joined Apr 27, 2007
You could use a op-amp wired as a voltage follower. You just have to connect the op-amp output to its "-" input, so negative feedback could be performed. For that you have to use an op-amp capable of delivering 200mA (I had in mind the LM324 but that won't do).
You could search in: http://www.national.com/products/tree/table.do?treeId=14.

But do you really need a current amplifier? Or you just want to process digital signals?