Re: interesting part

At 05:12 PM 8/28/97 -0700, you wrote:
>
>Apex Microtechnology SA02 PWM amplifier
>
>80v max in 10A continuous out. Looks like you could run it off of the +V
>side of either the WG or G08 supply (needs +12 too..) and have most of
>the deflection circuit done, except for an external error amp. Has current
>limiting and overtemp protection. I'll have to find out how much they
>want for them.

Getting a PWM amplifier to run the deflection would be really cool (pardon
the pun).

Can this amplifier use split voltages? Or is it a bridged output? You're
going to need to drive current through the yoke in both directions.

If it's a bridged output you might have a hard time supplying the error
correction needed. I'm not sure where you would tap to determine the amount
of current flowing through the yoke.

Be sure to use a current to voltage resistor as your part of your feedback.
Most amplifiers use voltage feedback as their error correction. The big
difference between the deflection amps and a standard audio amp is the way
they feed back the error correction. Since the yokes are very inductive,
the voltage across the yoke does not always indicate the current flowing
through it, and the amount of deflection is controlled by the amount of
current flowing through the yoke, not the voltage across the yoke, hence the
current to voltage resistor -- those big 10-20w Non-Inductive resistors that
all deflection boards use.

Good luck, I've seriously thought about doing this, but it's that damned
*time* thing. Somebody want to sell me some of their free time?

-Zonn
Received on Thu Aug 28 17:34:11 1997