ALC 'problem'

[Multi-Volti Devices]

I haven't tried it, but see if you can use this idea to solve your
polarity inversion.

Firstly, let me say that I don't know whether ALC voltage is a varying
DC level, or a modulated signal.

My idea is something I learned from Heath schematics. The power input
circuitry for many small low voltage Heath products was able to handle
ac or dc. The slick part was that they woulds handle either dc polarity.
This was accomplished by applying the input power, be it ac, +DC or -DC
thru a rectifier bridge. With the desired output from the bridge wired
to it's load (usually the +DC was utilized), the bridge diodes would
'steer' the applied voltage thru the appropriately forward biased
diodes, always resulting in the desired polarity output.

If the modulation is required for ALC, perhaps this circuit could be
used without a filter capacitor. If excessive alc is available, a
resistive voltage divider string could be used.

The opposite problem, higher required ALC voltage than is available, is
another problem.

Murray

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