I'm using a solenoid with a fly-back diode 1N001 and a mechanical switch as in the below diagram:

enter image description here

Now I want to add this 24V indicator lamp in parallel with the solenoid as shown above to indicate the status of the valve.

My concern is would this lamp have an upsetting effect to the purpose/workings of the diode? If the lamp was pure resistive, I wouldn't ask this question but the lamp looks like made of LED.

  • \$\begingroup\$ You should read this datasheet. The lamp is a LED in series with an electronic current regulator. It may be used with 5 to 28 V DC. It is not pure resistive. \$\endgroup\$ – Uwe Feb 25 at 16:33
  • \$\begingroup\$ If not sure how the lamp behaves for negative voltages, you could always add another diode (like the fly-back diode) in series with the lamp (and anti-parallel with hte fly-back diode). \$\endgroup\$ – Huisman Feb 25 at 16:42

No, you have nothing to worry about, assuming you have chosen the correct diode for your design. The current from the solenoid will flow through the diode as normal, especially if your lamp is an LED. The fly-back diode will clamp the reverse voltage to about 0.8V or so (its diode drop). Be sure your lamp can handle this reverse voltage. Then there should be no concerns.

If you lamp is just an LED in series with a resistor, the LED will be reverse biased and no current will flow in the lamp. If there's any active circuitry in it just be sure it can handle the ~ .8V of reverse voltage across it.

  • 1
    \$\begingroup\$ Sadly the datasheet leaves a lot to the imagination, I would have expected an Absolute Maximum section. \$\endgroup\$ – pipe Feb 25 at 16:22

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