I'm building just a basic 12v regulator circuit with a LM7812 (it will be knocking a 15v wall wart down to 12v) and pretty much every example I see online uses 100uF caps in the circuit. How critical is that 100uF value?
I have some a little lower and some a little higher on hand but I'm not clear on why its 100uF or if that can change. (Generally, I'm not clear on when to use what value cap yet in circuits…)
Best Answer
If you look at the data sheet you will see that the minimum requirement is a 330 nF capacitor on the input if the regulator is situated some way from the rectifier reservoir capacitor and a 100 nF capacitor on the output to improve stability and transient response. Those are the minimum requirements for the regulator itself. Additional capacitance is often provided for the circuit that is being powered; it depends on the characteristics of the load, and 100 uF is a popular value for most applications. I wouldn't worry much about the value, and use whatever you have.