Hi, I'm a little bit daunted posting on here with my comparatively feeble electronics knowledge, but here goes.
I'm looking to make a 125 kHz RFID programmer. I made one with an Arduino using an off-the-shelf module but it's not as versatile as I need it to be. So I thought I'd try and make a circuit myself. The programmer needs to create a nice 125 kHz signal for its antenna (typically a coil and capacitor at resonance for obvious reasons, wavelengths are pretty big). To communicate with the chip in the RFID tag, the field needs to be modulated with on-off keying.
I've been reading around the internet, looking at what other people have been done for RFID projects. Some seem to have had success using a PWM input into an LC tank and using the coil as the antenna. Obviously there's no amplification stage but I don't need a huge read range so I don't think it's absolutely necessary. I thought maybe I could use an output from an IC, connected to the base of a transistor to do the keying.
Now, part of me thinks I ought to go for a traditional oscillator design, like a Colpitts. But then I wonder whether I might be getting a bit out of my depth. I know what inductor and capacitor values I need for resonance, but it seems a bit overwhelming.
I appreciate that this post might sound like me babbling on but I suppose I'm asking for any advice or thoughts that might help me. I feel that this is doable but I probably need a shove in the right direction.
Many thanks,
Rob
I'm looking to make a 125 kHz RFID programmer. I made one with an Arduino using an off-the-shelf module but it's not as versatile as I need it to be. So I thought I'd try and make a circuit myself. The programmer needs to create a nice 125 kHz signal for its antenna (typically a coil and capacitor at resonance for obvious reasons, wavelengths are pretty big). To communicate with the chip in the RFID tag, the field needs to be modulated with on-off keying.
I've been reading around the internet, looking at what other people have been done for RFID projects. Some seem to have had success using a PWM input into an LC tank and using the coil as the antenna. Obviously there's no amplification stage but I don't need a huge read range so I don't think it's absolutely necessary. I thought maybe I could use an output from an IC, connected to the base of a transistor to do the keying.
Now, part of me thinks I ought to go for a traditional oscillator design, like a Colpitts. But then I wonder whether I might be getting a bit out of my depth. I know what inductor and capacitor values I need for resonance, but it seems a bit overwhelming.
I appreciate that this post might sound like me babbling on but I suppose I'm asking for any advice or thoughts that might help me. I feel that this is doable but I probably need a shove in the right direction.
Many thanks,
Rob