Car project geting spike from the car elect circui

I am using a circuit in my car that include some CMOS logic gates and 555 timers.
I know this chips work OK within 3 to 15 Volts.

The projects work perfectly in my bench with a 12 volt battery BUT when I conect it with the battery from the car it work ok until I actvate a switch in the car like the door lock.

Its look like my project is getting some type of spike or glitch from the car electrical circuit.

What I have to do in order to fix this??? Do I have to install some kind of debounce circuit???

Do I have to install a Voltage Regulator???

Can somebody give me detailed instrucctions or point me to a wep page were I can find more info about this or a circuit that I can copy.

Thank you for your time and help.

Posted by malibu 307 on 25/08/2003, at 01:58 GMT

Heres something to iliminate spikes

Hi malibu,

What you may want to try is a 1n4001 across the supply of your circuit in reverse ie. anode end of diode to -volts of supply and cathode of diode to +volts of circuit, this will stop any back emf going through your circuit. Also what you may want
to try is a decoupling capacitor also across the supply rail of your circuit a 0.1uf capacitor polyester and try a mylar type but what is very important is to have some sort of smothing capacitor(electrolitic 220uf-2200uf also across the supply of your circuit.

I know a bit about power supply design and this may help you ok and good luck

Posted by grant1 on 20/10/2003, at 14:06 GMT