Is a 1N4004 Rectifier Diode 1A 400V good for a fly back diode on a 12 volt electric mag lock, should not use more than 0.5 amps. Reason I ask is I don't know if rectifier diode are specific for a different purpose
Yes that would be a typical diode to use for that...
Flyback current is the same as the operating current was through the solenoid.
But that current only lasts for milliseconds, and decays quickly.
The 1N4004 has a continuous current rating of 1Amp, but a peak current of up to ~25Amp.
Should not be a problem to use that diode for a mag lock that draws several amps.
Assuming you don't use PWM.
Thanks for the responses!