The input is,purely mechanical, consisting of the original contacts. So I would assume the gate would live at or near the 12vdc supply when the contacts are open.
Would a PNP transistor be a better idea? The clock wasn't installed yet. Thanks : > > See the picture. This little circuit was added to an older car clock > (electric wind by solenoid) to eliminate most current drain across the wind > contacts which tend to burn/pit over time. It worked just fine for 4 days, > then the solenoid went up in smoke and the mosfet shorted out ( I don't > know which event happened first) > > Firstly..a fuse or current limited power supply would have been a good > idea.... hindsight is always 20/02... > > [image: relay.gif] > They drive the solenoid very hard because it's only activated briefly > every 2 minutes or so. .It's not designed for continuous operation of > course, just a lot of pull to kick the wind actuator. In fact, if the > contacts stick the coil gets HOT in a big hurry! The math says the current > drain would be ~5 amps continuous, the coil winding looks like 30 gauge > wire. When it was working I measured about 3.2 ohms across the coil. > > My question is, do I need more protection for the transistor? Maybe a > diode? There is a 'flywheel' diode across the coil. > > It's possible the coil simply failed after 50 plus years, it's also > possible the transistor failed and destroyed the coil. The transistor is > rated at 19 amps so one wouldn't think it would fail... > > Thanks for any input.. > > > > > -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/8a620102-1d02-4fb9-acc3-953f98a58b84%40googlegroups.com.
