Need to bring down a 12V PWM/TTL signal to 5V with a LM7805. Do i need the capac

Hey folks,

This is not a strictly arduino question, but somewhat related. I bought a laser for my 3D printer and it requires a 5V TTL/PWM signal to control it. My printer only spits out 12V PWM signal and someone allready pointed to me that i could use a LM7805 to lower the voltage.

In the how to's the LM7805 I found that people suggest to use some capacitors to smooth out ripples it might produce. however, it feels like these would mess with the PWM signal.

Do i really need those capacitors?

Hey Liam....Usually, LM7805 is a voltage regulator and common circuit for it is it has 2 capacitors both at the input and output side.

1uF Ceramic capacaitor at - INPUT side
10uF Ceramic capacitor at - OUTPUT side

However, you can try out other caps like 0.22uF at input or 0.33uF at input according to your application. But, above mentioned values should go well.

Typically the higher uF cap is on the input side, and the lower uF cap is on the outside.
10uF on input and 1uF on output has worked well in my applications.

liamkonviks:
My printer only spits out 12V PWM signal and someone allready pointed to me that i could use a LM7805 to lower the voltage.

Are you talking about the power output or the signal input. I wonder if you are getting the two mixed up.

TTL implies 5v.

Please post a link to the datasheet for the laser module.

...R