Re: [ATM] Making glass blanks.

["Bob May" <bobmay@nethere.com>]

The PWM design is indeed the most efficient.  The SCR and TRIAC control
systems are all PWM designs.
The problem with full analog control is that you build  circuit just for
that purpose and you have to be very careful of cleanliness of the
mechanical parts of the circuit as you are asking the electronics to hold a
charge on a cap for a long time and to discharge that cap at a very regular
rate over another long period of time.  Better to use a computer which can
repeatedly give the same time each time it is requested to count down the
clock ticks.
----- Original Message -----
From: Geoff Nelson <gjnelson@absamail.co.za>
To: <atm@atmlist.net>
Sent: Friday, May 14, 2004 12:56 AM
Subject: Re: [ATM] Making glass blanks.


> > A fully self contained circuit would be great, but circuit that can
> > read the temperature and give it to the computer, and another circuit
> > that would be able to lower the voltage to whatever voltage the
> > computer tells it to would work just as good.  I have no problem
> > writing software.  I already have a temperature sensing circuit, but
> > the circuit to control voltage eludes me. This is probably very simple
> > for someone, and hopefully that someone subscribes to this list. <g>
>
> How about PWM circuitry. I am not an electronics expert but have
> thought about this kind of thing. Current control is often done by
> PWM which means your net power will be controlled if your voltage
> remains constant.
>
> It may be possible by using a number of light dimmer circuits in
> parallel with the same input signal.
>
> Your temperature sensing circuit will give you feedback control so
> you should be able to compensate for any differences.
>
> The control of the system could be done using a similar concept to
> Mel Bartel's system for computer control of a telescope.
>
> All these are opinions that may be based on sound principles of which
> I am unaware. If they are actually usable it is coincidental.
>
> Geoff
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