Another newby question dual simultaneous readings?

Hi all, I’ve been perculating thoughts and can’t seem to find the answer.
And I know you guys will know.

Here’s my question.

Im doing a door lock.
I have two separate 600lb magnetic locks on the door.

I have both hooked to a 125khz module right now.
I’ve cut a hole in the vehicle body to allow the signal to penetrate. So the module can read the key from outside the vehicle.

I’m wondering if it would be possible to use both a 125khz and 13.56 mhz module simultaneously?

So, have a 125khz module hooked to one magnet. And a 13.56mhz module hooked to the other magnet. And use the same access hole for both antenna??

Would it work for both to be read at the same time? Would they interfere with each other?

Also, if you have a ring or wrist band that can do both 125 and 13.56 can they both be read at the same time?

It just seemed like it’d be a lot more secure with using two different frequencies?

Not sure if it’s a viable idea though.

Is this a coherent question? Lol.
Please let me know if I’ve left out important details.

I’ll give it a try

Interesting concept and I can see how this will work.
We have discussed something similar before, as basically a 2fa lock

Im happy to answer this as theorhetical, but it sounds like you have the physical set up basically ready to go.
Personally I would have done a bench test for ease of testing, but lets see how we go…

I am just going to throw this out and not really formatted, so it will be a bit of a mess, and formatting will take me ages, but there are a lot of questions bouncing around in my head and I dont want to miss any of them, and im on my phone, so just a little less convenient

And its working? if so great

Theoretically yes, and this is really the only question that matters.


THIS is the crux.
To get this consistent and reliable may be the biggest issue here, but I have a couple of ideas to help increase this possibility.

Truely the SAME time may never be reliable enough to be viable BUT one after the other in quick succesion may be more realistic.

To do this I would, for example, Place one antenna above the other, then my opening motion would be a downward swipe across the 2 antenae and probaly using a NExT as an implant or a dual freq ring/ wristband.

I would have each of the readers set on a ~3-5sec OPEN to increase my chance of BOTH being opened.

I get your logic, and don’t disagree HOWEVER Personally I dont know if its worth ALL the considerations that come with adding an extra reader.
Individually, the readers are a simple install; together they are 2 simple installs, BUT they add unnecessary considerations .

  • If somebody can grab one of you access cards, they can probably grab both.
  • Is the car worth this hassle to somebody else?
  • Are there other access points that somebody could use to steal your car? Smash quarterlight, door lock, slim jim
    Personally I would stick with the simplicity of one reader.

But thats not what you asked, So therfore I do still have a couple of questions for you from a design perspective, just to help you make sure you have considered some options

  • Antennas not backed on to metal, the face covered with non metallic (including aluminium)

  • Orientation of antenna optimised for xSeries implant (the path you should be going down)

  • power considerations
    ** 2 access units will draw twice as much.
    ** Have you done the power calcs?
    ** do you have a LVCO to protect the battery?
    ** What happens when there is a power loss (Is your door unlocked or are you locked out?
    ** Do you have alternative entry option?
    **Would a Solar trickle charger help negate the current draw satisfactorily?

your question is far more coherent than my answer, sorry about that.
Ive probably missed a couple of things, but hopefully my answer is helpfull enough

heres MY abridged answer

It is possible, but just stick with one reader

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Thanks for being so helpful!!

I don’t know that I have enough of a level on the forum to reply with all the quotes imbedded (or if I do I haven’t learned yet). So I’ll try to make it make sense.

I don’t have a 13.56 module, but can definitely get one. It takes 3-5 weeks off of aliexpress.
I just got 4 of the 125khz ones that didn’t have the known fault from there.

I reallllly appreciate your time answering, and the formatting and thought and time put into it.
Yes, my 125khz module is working great for the door. No issues being read/working, etc.

“can they both be read at the same time”
Yes, this Is the crux. I have a 2 1/2" hole (yes, inches, and fractions, sorry, lol 6.4cm). cut in the side of the vehicle. I could definitely do a time delay. Assuming the new modules I’ve gotten have one built in… I think it’s a 1 second delay right now. If there’s enough room with the hole to get a signal to both modules, but I think there is.

I’d need a system that others can access too, so a dual frequency wristband, ring, etc would be perfect. The vehicle is a bus I’m making into an RV.

I’ve used epoxy to fill the access/reading hole, and I used a plastic cutting board on the inside to separate the antenna from the metal wall. I’ll try to upload a picture. It works well.

Power shouldn’t be an issue. I’ll have 4200 watts of solar, and huge batteries, and likely a generator backup, so the power should be constant. I don’t have a LVCO, but should be able to program my solar system to auto engage the generator if they ever get that low.

Power loss results in normally open, so the door would be open.
There would be exit switches hidden on the outside. I’d just need to have two close to each other to activate both in this case.

No alternate entry options. Except the exit switches.

This is a custom door with a custom RV. It will end up being my home (yes it will have windows if I can get a picture, it currently doesn’t. The door has lexan “glass” and yes, there are always ways to break in, but it would be theoretically difficult unless one bashes out the windshield. No slim jim or anything would work. There is no external handle or lock.

The reason I’m posing the question is that naysayers have always told me the RFID is not very secure and that the door would be easily opened by someone who knew about RFID. (for example there’s supposedly universal “keys” that just open everything?) Obviously, I’m not well versed in it…
So I was thinking if one had two different modules it might make it more secure, and keep the honest thieves out, lol.

Thanks again for your reply! I can order a 13.56 module to play around with. I could even have two separate power supplies so that if one of the systems fail the other is intact.

Or maybe just stick with the one reader, haha.

Still pondering, thanks.


just highlight the text and a quote button should show up, like this


That I understand

AH, yes, I remember now

You are at MEMBER level, so sharing images should be no worries
EDIT ( I see them attached now )

Link? I can have a look for you if you are unsure

Yeah, no worries there

Don’t listen to idiots. especially idiots that can’t back up their statements or provide links.

rebut them with this
“A mechanical lock can be easily opened by somebody who knows about locks”

Both are slightly true, but also neither accurate nor realistic…

Here’s one

Sledgehammer GIFs - Get the best GIF on GIPHY

But as far as RFID skeleton key, It does not exist, so ignore those idiots.
Just like physical keys don’t have a single skeleton key.

Now, let’s take ME as an example, I would say my skills in physical and RFID locks are on par, and there are other people with far better skills in both

The LF system you have, would be easy to clone BUT people would need:
The Need and Want to access your bus
Know which RFID system you are using
Know where you are keeping your key/fob/implant
The right tool to clone it
Need to get personally “close” ~10mm ( there are some tools that can extend that range ~1m ) and implant, they would need to touch you with their tool :rofl: .

So you are correct, If I was inclined, I am confident I could get this from you with the tools that I have, but I would have to know who you are, where you are, and get very close to you

If however, you went down the mechanical lock route, I would have 2 attack vectors ( and the way I would choose ), I would simply wait until you moved away from your bus, and I am equally confident I could get into your bus, I would just wait until you moved away from it, I wouldn’t need to get close to you, OR I would wait to get an opportunity to get a photo of your key and make myself one. ( photo of keys when put on the table at a cafe etc. )

How to keep me out
Install a DESFire access system, utilising security features
Don’t tell me you have one
use an RFID blocking wallet/ or have an implant

Mechanical Lock
Install a Bowley Lock

I would also say, the people that have this same knowledge are probably not the people that would use it against you.

The person that would, are more likely to be like this


The people telling you about universal “keys” have far less knowledge than you do

Can’t hurt, they are cheap, so nothing lost

If you run them in parallel. that would work, but I don’t think it is practical

Ha, well, now you have reminded me it’s the bus, with “unlimited” power. To me your dual frequency option is now a more viable option, not saying you SHOULD, but just now it is more POSSIBLE

Me too…
What you have now is working, and also installing an HF option is trivial and you will achieve the 2FA that may make you feel more secure

I would just say, you probably need to asses your threat model

This is the most important thing I think.
My threat level is probably quite low.
And there’s a much higher chance of the guy with the sledge hammer trying to get in than some computer hacker.

So I think maybe I’ll put in the power leads and maybe a mount for putting in a second module in the future, just in case. But I won’t bother with hooking anything up now.

Essentially it’s just introducing another level of technology that can fail. Or at least fail to work in sync with the other one. And it’s not broke so…

I’ll answer the other stuff as well. But will be holding off.

I think I’ll get a couple of the 13.56 modules just to play with.

This is the link. I read up on it and it says theres 1 second and 5 second options. So that’d work fine.

I’m going to get the 13.56mhz versions of this same board.

They were likely looking at something like this. But, like you said, you need access to the key. And knowledge of the system. I’ll ignore that for now.
They were also saying it would randomly pop open from interference as well. Hopefully I can discount that as well.

Thanks again for the insight and the help!
It’s much appreciated.

And I did the reply in my phone to experience the pain you went through with your original reply. Haha. It was significant. :rofl:

Thats what I would do

A Universal RFID Key
That us a neat little project but you can also buy an off the shelf version

same goes for a key.

If you had access to the key, you could take a photo abd cut your own.
They would need to re-key the lock to keep you out

On a fob/card, this is kind of true, but barely.
You can also unenroll it, change it, so if someone saw it, they would see a red herring.
Also, they cant see your implant.
The threat is easily mitigated/irrelevant

I meant to share this in my previous reply.

Heres a great little video

Thanks again.

I ordered the 13.56 module and will play with it.

But not worry about it for now. There’s plenty else to do.

Thanks for the help!!

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