# Can I use the Solenoid lock without an external power supply?

I have a question about the Solenoid lock: can I use it with a 12v relay module without an external power supply?

I'm using Raspberry pi 3 model B.

• Yes, you can use batteries, eg, Lip0, lead acid etc: raspberrypi.stackexchange.com/questions/124290/… Apr 11, 2023 at 2:47
• @tlfong01 a battery is an external power supply Apr 11, 2023 at 6:06
• There's only 3.3V & 5V available on an RPi so you'd need a buck converter to run a 12V solenoid. It would be possible if the current draw for the buck converter & solenoid is tiny but you'll be better off with a battery or 12V external power supply. Apr 11, 2023 at 6:44
• Please edit your question and add more details about "the Solenoid lock". (Model, type, link to data sheet.) Electromagnetic components draw a fairly high current and and can create currents when switched off. You normally need an external transistor and protective circuitry like a flyback diode or maybe even a relay, and external power supply.
– Bodo
Apr 11, 2023 at 15:34
• Thank you everyone, but I think you didn't get my question someone told me that I can use relay module with 12v without needing an external power supply so that's why I'm asking. Apr 12, 2023 at 15:35

### Your question is a bit vague. Perhaps the best answer is to show a couple of alternatives schematically:

I'll assume that your reference to `"a 12v relay module without an external power supply"` is blether, and your question is rather how to supply 12V of power to a Solenoid-driven door lock.

The answer to that question is an unqualified "it depends on how much power is required"! Shown below are two approaches:

##### Option 1:

IF your Solenoid doesn't require more than say 100 milliamps of current at 12VDC, you may be able to add a DC-DC converter to boost the 5V RPi Supply up to 12VDC as shown below.

simulate this circuit – Schematic created using CircuitLab

##### Option 2:

But unless you've got a substantial 5V RPi supply, I think the external supply may be a better option - shown below:

simulate this circuit

### Other Details:

These schematics aren't detailed enough to actually build a circuit. That's because you didn't give enough information to support these details. Suggest you now do a bit of homework, and edit your question to make it clear enough to allow someone to help with a properly detailed answer.

• Ok thank you so much. Apr 12, 2023 at 15:36