Re: How do you connect a 12V DC solenoid to a 24V DC circuit?
- The diode to use as a snubber, could be almost any cheap silicon diode as it
is reversed across the coil, it only has to cut off the back emf when the
coil is switched off.....As long as the diode has a reverse rated voltage
say at least double that of the supply (1n4001 is 50 Volts, 1n4002 is 100
Volts 1n4003 is 200 Volts for example).
Also the 1n400x can take short duration current spikes of up to 30
amps......more than enough.
See here:- http://www.diodes.com/datasheets/ds28002.pdf
To anyone starting out in Electronics, never ever buy just one of the cheap
components, whether mail order or driving to the shop (petrol/diesel
Look carefully at the supplier and often there is a good deal for say 100
diodes, enough for years of fun, at around the same as the postage costs.
The same goes for resistors of the cheaper types, I always buy 100 at a
Buy for at least for the same value as the postage/petrol/diesel
costs.....you will never regret it. Store carefully in small labelled boxes
for future usage.
- Thanks again for the good advice. I don't think a resistor is needed in this application. When the devices are turned off, the devices will remain off for at least three seconds.
--- In Electronics_101@yahoogroups.com, "Kerim F" <ahumanbeing2000@...> wrote:
> I like adding a small remark. When I switch a relay 12V (or 24V) coil using a transistor with Vceo > 30V (or 60V) and the relay off response should be `relatively' fast, I add a resistor in series with the reversed diode having a value about the coil's one (or a bit less). In this case, the applied 'transient' voltage at turn off will be about 2*Vcc but the coil energy will also discharge much faster (ratio about Vcc/0.7).
> --- In Electronics_101@yahoogroups.com, "Andrew Mathison \(Alice\)" <mathison@> wrote:
> > You are correct, always place a reversed diode across any coil that is being
> > switched on and off with DC voltage.....the so called "Back E.M.F." can be
> > many times larger than the original voltage source, that's how a car's
> > ignition system makes high voltage for the spark plugs from 12 VDC.
> > Regards
> > Andy