61354Magnetic Tracking Herbie circuit
- Jun 6, 2014
Here's the simplest circuit I've been able to find for reading recorded magnetic pulses. The circuit is from the old National Semiconductor Linear Applications Handbook. No doubt there are newer quad comparators out there that can run rings around the LM139, but this will do as a starting point for discussion.
Two comparators would be used for the 2-channels of the stereo tape head tracking idea I've been talking about, leaving two comparators free for other purposes.
I don't know if I'll need to differentiate each channel then use the zero crossings to do peak detection; that's the way it would ordinarily be done if the object were to recover recorded digital data. I'm only interested in the relative phase and amplitudes of the left and right pulses, so maybe following the amps with a simple phase discriminator circuit would do the trick (or at least part of it).