Help

KiwiNuB

Hi

I know this all going to be basic stuff, but help would be appreciated.

I am using a basic stamp to control a number of DC motors through a 595 shift register.· The 595 is linked to the motors though an NPN transistor and relay (using the basic circuit detailed on page 302 in Scott Edwards book - "Programming and Customising the Basic Stamp Computer", snd Edition).· I have a diode across the relay to protect the transistor.· The program essentially turns the motors on in sequence for short periods.· One motor is fairly hefty and draws about 15A at 12v.

I am getting all sorts of random events occuring.· Some times the program works perfectly, other times I seem to get noise flowing back to the BS, other times two relay trigger at once despite the logic circuits being correct.

Any help would be appreciated.

Thanks in advance.

LoopyByteloose

Try disconnecting the 15amp motor and observing if the circuit cleans up its behavior.

If so, you can focus on specific fixes [noparse][[/noparse]like adding a capacitor and/or ferrite bead to the motor lead; improving your power supply; building a better drive circuit for that particular motor].

If the problems don't go away, it is something more general [noparse][[/noparse]like no bypass capacitors on the ICs; too small a power supply]

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······································································ Warm regards,····· G. Herzog [noparse][[/noparse]·黃鶴 ]·in Taiwan