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Topic: Seeking guidance on electronic locks, and battery/power sources (Read 376 times) previous topic - next topic


Hi everyone,

Recently gotten into the wonderful world that is arduino, and seeing some of the projects out there, I wanted to see if I could rig up my own project.

I'm looking to create a system in which a cabinet is locked (using an electromagnetic lock), and to unlock it, an RFID scanner needs to be activated across the room.

The coding part isn't my issue - it's my knowledge of the hardware and what the ideal/most efficient hardware to use would be.

Here's my thinking so far..

RFID sensor hardware:

Arduino Uno
RFID Scanner
all connected to a wired power supply

Here's where I start to get confused...

For the Electromagnetic lock inside the cabinet, here's what I THINK I need..

Arduino Uno
An electromagnetic lock of sorts (nothing like a 600lb magnet, but something that can't be easily pried open.. maybe 100lb?)
Some form of power supply that will last a significant amount of time (at least a week)
Unfortunately, there's no power source available nearby at all.

Here's my questions:

- first and foremost - is this even achievable?
- do you guys have any product suggestions/links to a relatively inexpensive, reliable and efficient electromagnetic lock?
- what type of non-wired power supply can I achieve that will reliably last a week long in a cabinet and keep my cabinet locked?

Thanks in advance for any suggestions or advice you can provide!

I'm also open to other types of locks that are maybe more power efficient that will serve the same purpose, but electromagnetic locks seem to be the cleanest delivery


You can get solenoid operated door locks. Here's one from Jaycar, with a good description of its operating method. You should be able to power this off a 12 lead-acid battery for years, depending on the usage.
"The problem is in the code you didn't post."


Hi everyone,

An electromagnetic lock of sorts (nothing like a 600lb magnet, but something that can't be easily pried open.. maybe 100lb?)

That type requires a considerable power supply.

The type mentioned by morgans is probably the most economically available type
but probably not suited to a cabinet.

You could try using a simple servo to retract a latch.
If its a display cabinet you can hide the servo out of the way and use a Bowden cable (bycicle brake cable)to operate the catch.

If the battery goes flat do you have a secondary means of opening ?


Thanks for the reply guys!

- that electric strike lock looks interesting, but there's 2 issues..
a) it looks like it would require a considerable power supply
b) it's a bit too big of a footprint for a small cabinet application

- generally speaking, what would be my best option for a 'portable' power source for a long term duration?   :smiley-slim:

- are there any mini/small scale electromagnets available out there?  what's the smallest one, with the lowest power drain?


You can buy latching relays - give them a pulse and common connects to NC, pulse the other direction and it connects to  NO.
I wonder if you can find similar latching solenoids - pulse one to move into locked position, pulse the other way to move back.
Or wind your own with some mechanical bits.
H-bridge drive to supply the bidirectional current.

Or use a servo - turn one way to lock, power down.
Power up, turn back.
You see that in geocache boxes.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

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