Hi all I am learning circuit design.

I have a logic probe circuit that I have breadboard and testing.

I used my multi meter to check the amps/milliamps and the max reading while checking a test PCB is(.024) .

I work on lcd tv / monitors / laptops / etc.

Question:= Is this an acceptable amount of amps/milliamps to draw while voltage testing a PCB that will not damage the PCB under test ?


sch below.

Thanks for your comments.

 

I believe your input impedance will be too low for many logic circuits. Also your transistors are the wrong way around; C and E are reversed Also your buzzer is connected directly to the input. I think there are two or three other problems as well.

 

I would like to have the buzzer sound if it is on a PWM pin or sine wave, as a basic test if the IC is puting out a signal.
Thanks for all the comments / help.

 

Does anyone know if this is an acceptable amount to use as a logic probe ?
Thanks