Hej Mikkel!

A PSU based on a 7805 is okay, if it is a propper design. For that amount of current you need some kind of heat sink


Maxim/Dallas does a lot of supervisor chips. They do some nice litle device in a to92 or sot23 case. They will provide active high or active low reset. The other one could be made with a few resistors and a NPN transistor.

Or you could use a DS1707 in a DIP8 package, with both active high and active low output, and a PSU monitor with a PFI output pin.

The diodes in you ULN2803 might be sufficient. But your problem could be noise radiated from the tracks betwen the relaiscoil and the '2803. If you put the diode directly on the relay, the noise is killed before it can make any trouble.

Ha' en fortsat god søndag

Per Guldmann