Hello everybody, ¿can somebody help me please?!!!!! :'(
I using a arduino duemilanove board, and LCD display LCM1602A (blue backlight), and a 74HC595 that drives a ULN2803A and this drives relays to 12VDC.
When I tested the relays to drive a load(with a PC power supply), I had conected the load trough a solid state relay, I mean, between the relay and the load is the SSR, under this configuration all has worked nice. now the configuration is without SSR(with 2 tiny cheap power supplies) , the weird thing is the garbage in the LCD once the relays turns on, the system continues working fine except the LCD(full of garbage!!!).
The problem is in the external electric system 110AC? cause noise for switching relay? or the internal electric system 12VDC? when the coil of the relay turns on?.
first I used 2 tiny cheap power supplies, one for 5VDC another for 12VDC then the garbage get very fast in the second or third switching.
After I used a PC power supply and the problem take more time to appear, 30 minutes or more.
I am pretty sure that is the power supply. I am using a IDE 0018 with the LCD library that comes with it.
Please help me. and Thanks for your time.