Maximizing RFID Reader Operating Range

Hey Guys,

First, as a bit of background for my project. I have connected an RFID reader to my Arduino Pro Mini. Initially, I had connected a 9V 650 mA adapter to the Arduino raw pin. However, when I connected a 9V 1A adapter, the read range of the RFID reader increased.

I'm trying to figure out the maximum current rated wall wart I can input attach to my Pro Mini so that I can maximize the read range.

Also, here is the spec sheet of the RFID reader - it looks like the operating current is 38 mA.

Any tips would be great, thanks!

SkiBum326:
Also, here is the spec sheet of the RFID reader...

Where?

Still, from your description, something seems amiss.

Sorry, right here:

Also, could you elaborate please? I'd be happy to provide more details.

Thanks,

Austin

SkiBum326:
I have connected an RFID reader to my Arduino Pro Mini. Initially, I had connected a 9V 650 mA adapter to the Arduino raw pin. However, when I connected a 9V 1A adapter, the read range of the RFID reader increased.

SkiBum326:
Also, could you elaborate please? I'd be happy to provide more details.

Maybe the 650mA supply is a dud?

What I'm taking from this is that you're running the RFID from the ProMini 5V pin?
When you had the ProMini running off a "9V 1A" the RFID did better than when using a "9V 650mA" supply.
Now that I see the data sheet, Page 2 (table 1) informs us that it can run from a wide supply range, 5-15V.
So, why not run it from your "9V" supply directly?

Perhaps you could dispel all doubt and attach or link to a sketch of your hook-up diagram of what you have going?
Or take a good quality picture with everything in shot?

The data sheet says the input voltage is:-

5.5V-15V input supply

So yes running it at a higher voltage will give you more range because the coil gets more voltage and so generates a higher field.

When I designed RFID readers we used to run them off 12V, but the higher the voltage the better the range.

If you want to increase the range even more then try changing the capacitors across the coil slightly.

I attached a block diagram to better illustrate my design.

Also, after attaching a 12 V power supply directly to the RFID reader, the read range increased dramatically.

Thanks everyone for the help!

Grumpy_Mike, one more quick question. When you say add a capacitor, are you referring to tuning the LC circuit to an optimal operating frequency, or something else that I’m not aware of?

Yes it is the LC tuning. This needs to be close to resonance but not bang on resonance. There is a peak range to be found just either side of resonance. Getting this right coul potentially double your reading range.

Ok. I'm actually tuning by varying the inductance (it's a lot more work, especially since the leads no longer exit the coil at the same place, but it seems to be an incredibly accurate method). Are there any benefits to tuning by varying the capacitance instead?

Are there any benefits to tuning by varying the capacitance instead?

Only that it is easy to keep putting smaller and smaller capacitors in parallel.