NOTICE: This webpage and associated files is provided for reference only. This is not a kit site! It
is a collection of my work here at the
University of Toronto in the
Physics department. If you are considering using any schematics, designs, or anything else from here then be warned
that you had better know something of what you are about to do. No design is guaranteed in any way, including
workable schematic, board layout, HDL code, embedded software, user software, component selection, documentation, webpages,
All that said, if it says here it works then for me it worked. To make the project work may have involved undocumented
additions, changes, deletions, tweaks, tunings, alterations, modifications, adjustments, waving of a wand while wearing
a pointy black hat, appeals to electron deities and just plain doing whatever it takes to make the project work.
Contact is Chris/Mirco for Aephraim Steinberg's Lab. The TOP coil modulation and drive is done with a signal generator
and amplifier. This circuit generates the AM (Amplitude Modulation) control for the signal generator.
The voltage range for the AM input on the signal generator (make? model?) is +6V for full signal to -3.7V for zero
signal, a 10V range. An external analog voltage from an arbitrary function generator which supplies step voltages
inside that range is fed into this circuit. The circuit simply tracks the step voltages with a controlled slew
rate (AKA dV/dt). The slew rate is adjustable with a user accesible potentiometer from 1Sec/10V to 30Sec/10V.
This controlled slew rate can be overridden with a TTL signal. When set to "fast", it will track at <100uSec/10V.
How To Use
Connect the supply ±12V at <25mA, connect the input to the arbitrary signal generator, the output to the AM input
of the TOP signal generator and the TTL "fast" control input to a TTL source. With "fast" low (false), set the
output slew rate with the pot.