Why is this RFID lock PCB such a secret?

Thread Starter


Joined Feb 23, 2021
Hello all,

Happy to have found a helpful forum here!

I'm stumped by what I thought would be a simple problem.

I'm retrofitting an old moped seat with an rfid lock, and this means disassembling the lock and using it's parts in my own 3d-printed enclosures, etc.

I have run into the problem that I need to get/make a handful of antennas, but I cannot seem to find a datasheet from the lock's PCB in order to spec the antennas for purchase.

I would even consider purchasing the PCBs just for the antennas if that were possible.

I've attached photos of two of the boards in question. They look different, but have very similar pinouts and identical functionality when in use, down to numbers of beeps on button presses and lock/unlock.

I have looked into different RFID boards like the RDM630/RDM6300 which have much more readily available parts and info, but have been unable to find anything that doesn't require a much more involved and expensive setup. These boards operate a lock on their own, sending power to a motor when the correct tag is scanned.

Through process of elimination, I've determined that the boards are 134.2khz rfid, and do not play nicely with 125khz antennas and/or tags in any combination.

So, can anyone find me a place to buy less than a thousand coiled magnet wire antennas resonant at 134.2khz?
Or how to make them? I have a lathe, I could wind a coil easily enough, I just don't know the math required to make such an antenna.

Ideally, they'd be ~35mm round antennas, but I can work around whatever I find.

At this point, just a datasheet for one of these boards would be a miracle for me.

Thanks for listening to me blather if you're still here! The photos are below:1a.jpg
You are treading on forbidden ground when trying to un-ravel RFID. So many security devices are based on RFID technology.
A key-lock Interrogator is needed...Rotsa Ruck!

Cheers, DPW [Everything has limitations...and I hate limitations.]


Joined Jul 1, 2009
@terbospaghetti Instead of focusing on the PCB, focus on the conductors from it. What exactly do they do? Power, Ground, and then hi/lo, code, fsk, another signal, what (from the remaining pin(s))? If you can figure out what the pins are for, you can make your own RFID pcb, easily. If you have an o-scope, that would go a long way to telling you what the signaling pins do.