All my Radio Shack carries are 200 volt 1 amp. Are they okay to use on my alarm or should I buy some 12 volt ones offline. I know the forward voltage drop on the 200 volt ones are 1.6. Any one have any ideas?

 

200v is fine

 

forward bias voltage should be around .7v. So the voltage on the other side of the diode will be 12-.7=11.3V

200v is the breakdown voltage. Meaning at 200V the diode will flow current in both directions. These diode are fine for your alarm use. You'll never see 200V in your car.

 

Thanks for the help.