Hi everyone. I am currently working on a circuit with a 18F452 PIC. I have developed my code and everything is working fine on breadboard + oscilloscope.
Next step was to connect the servos on the circuit. I noticed that whenever I connected the servos my circuit stopped working properly. Disconnected them and the circuit is working fine again. The response of the PIC showed that something was wrong with the power supply of the circuit so I connected the oscilloscope on the 5V (after the 7805).
What I noticed is that:
Servos DISCONNECTED - Powering up takes few ms and it is a clean line from 0 to 5V
Servos CONNECTED - Powering up is extremely noisy taking about 80ms+. Many times during those 80ms, the power signal drops 1V+ and then up again until it settles.
Questions:
1) Why this happens? I have few ideas but I think they are wrong
2) In order to fix it I tried to place a capacitor between + and ground after the 7805 (additional to the ones of the 7805 datasheet). The capacitor was 0.33uF. There was NO improvement. Do I need to buy a bigger capacitor?
I will put up a couple of pictures I took from the oscilloscope when I go home.
Oh and something else. The power supply was adjusted to 0.5A. I raised that to 1.5A and the circuit is working fine. The circuit uses about 8mA
Thanks for reading! Any advice would be really appreciated!
Next step was to connect the servos on the circuit. I noticed that whenever I connected the servos my circuit stopped working properly. Disconnected them and the circuit is working fine again. The response of the PIC showed that something was wrong with the power supply of the circuit so I connected the oscilloscope on the 5V (after the 7805).
What I noticed is that:
Servos DISCONNECTED - Powering up takes few ms and it is a clean line from 0 to 5V
Servos CONNECTED - Powering up is extremely noisy taking about 80ms+. Many times during those 80ms, the power signal drops 1V+ and then up again until it settles.
Questions:
1) Why this happens? I have few ideas but I think they are wrong
2) In order to fix it I tried to place a capacitor between + and ground after the 7805 (additional to the ones of the 7805 datasheet). The capacitor was 0.33uF. There was NO improvement. Do I need to buy a bigger capacitor?
I will put up a couple of pictures I took from the oscilloscope when I go home.
Oh and something else. The power supply was adjusted to 0.5A. I raised that to 1.5A and the circuit is working fine. The circuit uses about 8mA
Thanks for reading! Any advice would be really appreciated!