The scenario
A user needs a variable low-frequency pulse train to pulse an electromagnetic lock for access control or vibration testing, with safe inductive load switching.
What is in this drawing
Read the decisions behind it.
01
Use a 555 timer in astable mode to generate adjustable 0-300 Hz pulses from standard DC supply.
02
Wire the relay-coil load with a flyback diode across it to suppress inductive kickback.
03
Include supply decoupling and control-voltage filtering for stable timing.
Reuse this circuit when a simple adjustable square-wave oscillator must drive a low-current inductive actuator or electromagnetic lock in prototypes, test rigs, or educational labs.
More like this