Wire following robot - signal processing

Kiwi Bruv

Guys, I am building a wire following robot. I have successfully detected a 5KHz signal in a wire using an op amp in a detector circuit.

I'm now stuck. How do I make this signal suitable for a Picaxe input. I will have 2 or 3 sensors ultimately and need to have the picaxe know the signal strength for each sensor(proximity to the wire) and from this work out direction.

I was planning to put the sensor outputs through a comparator and use this as the picaxe input but I can't see a voltage change happening upon detection. I know the sensor works because I have an earphone rigged up.

I think I need to use a bandpass filter to clean the signal up a bit, but then how do I get the signal in a form the comparators or picaxe can process?

The supply is 12V, but I can use less if necessary. When detecting the amp output sits at just over 6V, but isn't it just showing the average value of the amplified signal? ie the signal is going 0 to 12 V at 5KHz

Help much appreciated.


We need to know a bit more about your transmit and detection method.
Feel free to e-mail me the circuit of your "detector" and I'll have a look for you.

If your dectector output is 5kHz with a strenght that is proportional to distance from the wire, then it could be a simple case of a single diode from the detector feeding a potential divider with a capacitor across the bottom resistor. A PICAXE analog input can then read the voltage across the cap.