DickCappels
- Joined Aug 21, 2008
- 10,169
Solenoids (at least like that one) require more current to pull-in than to hold in the actuated position. This technique gives the solenoid a high current to pull in the reduces the voltage across the solenoid and the total power dissipation until the solenoid is released.
You can find the amount of current necessary to hold the solenoid after it pulls in by experimenting with your bench supply and an ammeter.
After you find that current, figure out what value resistor to put in series with the solenoid then put a capacitor across the resistor.
When voltage is first switched on the resistor-capacitor combination looks a lot like a short so the solenoid appears to be connected directly to the power supply. The capacitor will then charge, reducing the power dissipated in the solenoid but causing the resistor to dissipate power. The overall power dissipated is less than it would be with just the solenoid and the power supply, and much of that power (into the resistor) can be dissipated in a convenient place.
You can find the amount of current necessary to hold the solenoid after it pulls in by experimenting with your bench supply and an ammeter.
After you find that current, figure out what value resistor to put in series with the solenoid then put a capacitor across the resistor.
When voltage is first switched on the resistor-capacitor combination looks a lot like a short so the solenoid appears to be connected directly to the power supply. The capacitor will then charge, reducing the power dissipated in the solenoid but causing the resistor to dissipate power. The overall power dissipated is less than it would be with just the solenoid and the power supply, and much of that power (into the resistor) can be dissipated in a convenient place.
