Hi All,
I was hoping someone maybe able to explain how the 'diode feedback' in a circuit I'm using works? I know it does but not how? Its a RFID reader working in the 125-134khz range using fdx-b protocal. I'm using appliction 2 on page12 of the data sheet(without the transistor, its all running at 5v) I tried to attach just the schematic but it wouldn't play the game! I would like to drive the coil at a higher voltage to increse read range using a H-bridge, looking at the circuit it appears that the 68k resitor and the 43k resistor form a potential divider? (pin rf is 1k to ground according the data sheet) If I've worked it out right, that means the first two diodes have 1.76v (running the circuit at 5v) above ground across them? As coil1 and coil2 alternate between gnd and 5v, how do the diodes increase the range? If I use my H-bridge to drive the coil (taking its input from coil1 and coil2) should the diodes have a seperate pdiv to put the same proportion of the voltage across the h-bridge at the head and tail of the first two diodes?
Thanks Geoff
I was hoping someone maybe able to explain how the 'diode feedback' in a circuit I'm using works? I know it does but not how? Its a RFID reader working in the 125-134khz range using fdx-b protocal. I'm using appliction 2 on page12 of the data sheet(without the transistor, its all running at 5v) I tried to attach just the schematic but it wouldn't play the game! I would like to drive the coil at a higher voltage to increse read range using a H-bridge, looking at the circuit it appears that the 68k resitor and the 43k resistor form a potential divider? (pin rf is 1k to ground according the data sheet) If I've worked it out right, that means the first two diodes have 1.76v (running the circuit at 5v) above ground across them? As coil1 and coil2 alternate between gnd and 5v, how do the diodes increase the range? If I use my H-bridge to drive the coil (taking its input from coil1 and coil2) should the diodes have a seperate pdiv to put the same proportion of the voltage across the h-bridge at the head and tail of the first two diodes?
Thanks Geoff
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