Hi all,
I've been thinking recently about trying to increase the range of my RFID reader system, I'm stuck with the lf type of RFID 127~134 kHz used for id in livestock. I've a reliably working system using the Atmel U2270b front end chip.
Range of these tags is quite short and as far as I can see there are two ways to increase range, a bigger reader coil or pushing more current through a given size coil?
I've got pretty much as big a coil as practical for my hand held reader so am now thinking of ways to get more current through. I think I'm going to have to use a MOSFET H-bridge and drive it with the PWM module on my pic as I think I've reached the limit of supply on the Atmel.
This is where I could do with some help, the reader at the moment uses a 9v battery and also has to detect a HDX transponder (which means the field is turned off to wait for the HDX to respond).
Is it practical to use a step up boost converter to charge a capacitor to a higher voltage, say 30v while the field is off then use the 30v to supply the H-Bridge and hence drive the coil at a higher current? All be it briefly!
I've been doing a bit of reading up and read that a capacitor used for storage is about 50% efficent? Is this correct? Anyone have any idea what sort of losses I might experience with the boost converter etc? I've a funny feeling they might be quite high.
Thanks Geoff
I've been thinking recently about trying to increase the range of my RFID reader system, I'm stuck with the lf type of RFID 127~134 kHz used for id in livestock. I've a reliably working system using the Atmel U2270b front end chip.
Range of these tags is quite short and as far as I can see there are two ways to increase range, a bigger reader coil or pushing more current through a given size coil?
I've got pretty much as big a coil as practical for my hand held reader so am now thinking of ways to get more current through. I think I'm going to have to use a MOSFET H-bridge and drive it with the PWM module on my pic as I think I've reached the limit of supply on the Atmel.
This is where I could do with some help, the reader at the moment uses a 9v battery and also has to detect a HDX transponder (which means the field is turned off to wait for the HDX to respond).
Is it practical to use a step up boost converter to charge a capacitor to a higher voltage, say 30v while the field is off then use the 30v to supply the H-Bridge and hence drive the coil at a higher current? All be it briefly!
I've been doing a bit of reading up and read that a capacitor used for storage is about 50% efficent? Is this correct? Anyone have any idea what sort of losses I might experience with the boost converter etc? I've a funny feeling they might be quite high.
Thanks Geoff