I am using a magnetic gate latch to hold a swing gate closed. It is rated at 24Vdc . It has a resistance of ~200 Ohms and a huge inductance. I am using it on 13Vdc, and it is taking about 3 sec before the gate can be pulled away from the latch after the current is interrupted.
I am looking for a way to control the inductive spike as the magnetic gate latch is switched off and shorten the delay before the gate can pull away and begin moving. Here is an LTSpice sim of both the Original Snubber and my proposed fix:
In the Original, only a Si Rectifier is inverse connected across the coil (Green traces for V(a) and I(L2)). The Better circuit replaces the Rectifier with a complex network consisting of the same Rectifier, a Capacitor, and two Resistors. Note the voltage V(b) and the current I(L2) which reverses slightly, but first gets to zero in about 1/4 of the time in the original circuit.
Does anybody have a snubber circuit that would dissipate the energy in the latch magnet even faster while still keeping V(a) below Vce(max) for the switching transistor and while keeping the dV/dt on the cabling to a reasonable rate (so that I don't glitch the Arduino)?
I am looking for a way to control the inductive spike as the magnetic gate latch is switched off and shorten the delay before the gate can pull away and begin moving. Here is an LTSpice sim of both the Original Snubber and my proposed fix:
In the Original, only a Si Rectifier is inverse connected across the coil (Green traces for V(a) and I(L2)). The Better circuit replaces the Rectifier with a complex network consisting of the same Rectifier, a Capacitor, and two Resistors. Note the voltage V(b) and the current I(L2) which reverses slightly, but first gets to zero in about 1/4 of the time in the original circuit.
Does anybody have a snubber circuit that would dissipate the energy in the latch magnet even faster while still keeping V(a) below Vce(max) for the switching transistor and while keeping the dV/dt on the cabling to a reasonable rate (so that I don't glitch the Arduino)?
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