Measure the wattage used by the heater at 24V and room temperature.
This is what's required to keep the oven at the proper temperature.
Lower the voltage to 20V and see if the heater draws the same wattage.
As a second check, measure the current drawn at 20V at startup and then
after warmup. The difference tells you how much headroom you've got
until the heater runs full on.
Ed
Mike Millen wrote:
Many thanks to both of you.
Is it safe to assume that the oven has its own temperature control
system?
I ask, because I'd prefer to run it from approx. 20v instead of 24v.
With a controller (& a room-temperature environment) I'm hoping that
it would still be
operating at its design temperature with a lower voltage.
Comments?
Mike
Bob Camp wrote:
The board looks a lot like a pull from a Lucent base station. The
voltages would all make sense in that context. The unit swaps in for
an LPRO and the 15V would be easy enough to come up with. I'd bet
they ran both pins off of +24 though.
Bob
On Mar 19, 2011, at 5:20 PM, Arthur Dent wrote:
The pinout shown is close. The oscillator supply voltage on the
one I have in circuit is +15 @ low current. The Oven requires
24VDC @ .25A and this drops to under 100ma when the unit
reaches operating temperature. There apparently is an internal
regulator on the oscillator supply and if you watch the output
level as you increase the oscillator supply voltage you will see
it increase until you hit about 13.5VDC then it remains constant.
This may mean that you could run the oscillator on either 15 or
24 volts but where I'm only guessing what's inside the case I'd
stick with 15VDC to play it safe. The pin next to the output that
goes through the on board diode is apparently an oven o.k. signal
that drops from 5VDC (cold) to around .8 when the oven reaches
operating temperature in around 3 minutes. This probably could
go to the base of a transistor with or gate input if you want to
use it to drive an LED. 0-5DVC on the EFC pin changes the output
by about 28Hz
-Arthur
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