basic square wave voltage pulser, low frequency

I posted something earlier about this, I am just hoping to get a little more insight. I am very new to arduino.

I need to make a basic low frequency (somewhere between 0 to 20 Hz) low voltage (5-50 mV) voltage pulser to stimulate some cells. I'm using a mega. I tried the simple blinking LED project for starters, but I am confused on how to implement the voltage output or how to regulate it. Should I just use a power supply and some resistors to make a voltage divider that produces the desired voltage? If so, how do I get the arduino to pulse this particular voltage? Thanks so much for the help, it is greatly appreciated. :)

Your blink sketch is fine, you just need to adjust the timing and change the LED pin from 13 to one of the pins on your board. Any will do, perhaps D7 for the sake of argument.

The pair of resistors as a potential divider goes on the output pin.

D7 —

< R1

---------- output

< R2

GND ---------

Google yourself a potential divide calculator to work out R1 and R2, where Vin is 5V.

low voltage (5-50 mV)

The voltage divider will work quite well, but consider to use a potentiometer for R2 [MIN -> 0mV] ... [MAX-> 50mV]