Hi, I trying to use a USB DAQ board to control and monitor an Optical shutter/beam dump. However, the out put from the DAQ module is 5v 29mA and I require 5 v and at least 50/70 mA to operate the shuttter. Is it possible to build a current amplifier and can anybody suggest the best way to go about this.

 

You could do it with an integrated amplifier or buffer capable of supplying that current. You would likely need a higher voltage than 5v to supply the IC, unless it's rail-to-rail.

Would be possible with an opamp with an emitter follower inside the loop, but then you definitely need more than 5v supply.

 

You could just use a transistor. Use your O/P to switch the transistor. Not quite sure why Norfindel said you would need more than a 5v supply. If you select the right bias resistors 5V should be more than ample.

 

Oh, sorry i didn't realized you need this just to work as a switch. I think that a logic-level mosfet used as a switch over the gnd wire of the shutter will do the trick.

 

Or a MOSFET and you wouldn't need to worry about bias current or anything else...

You could use an N-channel FET on the low side or a P-channel FET on the high side, and use the output of the DAC on the DAQ to control the gate.