3046

[Martin Czech]

Do you remember my experiments with the temperature chamber?  It is by far
overdimensioned, thus the heater can not blow.  It is impossible, because
the PSU can not deliver so much power.  This is the easy way. I don't
have to worry at all. If you want oxygen and fuel hoses not to be eroneously 
interchanged (BOUMMM), make it impossible via connection shape.  The japanese 
method.


In the case of an 3046 immortality is not so easy to buy.  Any kind of
such heater regulation MUST ENSURE AN UPPER LIMIT FOR TRANSITOR HEATER
POWER CONSUMPTION. This is because any kind of servo loop will get into
nonlinear saturation at start up, the I part must be killed then and
the sensor must limit the actual temperature to a safe limit.  I.e. if
the temp goes over that limit, switch the heater off.  If sensor and
heater are too far away, the actual heater temp could differ. In this
case current/voltage has to be measured to ensure power limitation 
any point of time. Since circuits need some time to settle after start
up, there must be some kind of POR that keeps things OFF as long as the
protection circuits are not effective.


Every circuit design that misses that kind of SOA limit is a failure.


m.c.

:::Date: Wed, 24 May 2000 12:54:54 +0100 (BST)
:::From: Ken MacBeth <macbeth2600 at yahoo.co.uk>
:::Subject: Re: 3046 
:::To: Paul Perry <pfperry at melbpc.org.au>
:::Cc: synth-diy at node12b53.a2000.nl
:::Content-Transfer-Encoding: 8bit
:::
:::Paul, I've been building Prodigy oscillators for some
:::time now. They are a great building block for more
:::sophisticated designs, and extremely close to the
:::minimoog mk2 oscillators. The nice bit is that you
:::don't need to go hunting around for TC resistors to
:::keep them stable. Problem is though, any time I use
:::the 1A regulators, the transistor oven blows. Someone
:::once suggested to me that while 3046 is cold, it will
:::drag to much current from the 1A regulator and then
:::blow. The bit that blows by the way is only the
:::heating element. The rest works fine. Are you familiar
:::with this circuit? I think it's at Anders Spontons'
:::site. i've actually been looking at designing an LM723
:::based PSU for future projects, as I only have a few of
:::the now obsolete LM79M12's left.
:::
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