diode across solenoid coil
diode across solenoid coil
(OP)
Conventionally I have always used a 1n4004 diode across a relay coil to prevent any back EMI. I have this solenoid application and was going to put diode across its coil. I have read previously that a fast recovery diode is recommended, rather thant the standard 1n4001-4004 series. Any thoughts on this?





RE: diode across solenoid coil
RE: diode across solenoid coil
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: diode across solenoid coil
RE: diode across solenoid coil
Let's not feed and care the myths.
Gunnar Englund
www.gke.org
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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: diode across solenoid coil
The magnetic field will decay much more slowly than without the diode, the decay of flux will be aproximatly exponential with a time constant of L/R. Note that the vale of L will change as the magnetic circuit varies due to armature position.
I once tried to improve contact life in the fuel pumps of a Jaguar E type with diodes but the delay made the solenoid operated pumps cycle time to long to give good fuel delivery at large (heavy footed) throttle openings. The final cure was an arc suppressor of 10 ohms and 0.01uF in series over the points, just like SU used to fit. An alternative cure would be a voltage dependent resistor or possibly a zenner over the switching device.
RE: diode across solenoid coil
RE: diode across solenoid coil
The problem with a resistor is the power draw goes up whenever the solenoid is energized. In this day & age of energy conservation, that's not necessarily a good thing.