[time-nuts] 10811-Parts... (Using the thermal regulator circuitry)

[Richard (Rick) Karlquist]

The 10811 oven loop is only barely stable.  It's stability
is limited by the amount of capacitance that you can
get in a cap of the size that will physically fit.  BTW, this
cap must be of the foil type, not the metallized type.
If you are building a knock off of the 10811 and you can
fit in more microfarads, you can make the loop work better.
In the 40 years since the 10811 was designed, AFAIK, there
as been zero (0) progress with respect to the capacitance
per cubic centimeter of foil capacitors.

Of course, the real solution is to use a PII^2D controller
like the E1938A.

Also, if you are not using a 10811 oven mass, then all bets
are off with respect to the oven design.  You'll be starting
all over from t=0.

Rick N6RK

On 9/14/2019 9:41 AM, Ulf Kylenfall via time-nuts wrote:
> 
> Yes, I have more or less cloned the temperature regulation circuitryand used it for various heat control circuitry using other/similarsemiconductors that can handle elevated temperatures.
> The basic principle is nothing exotic. It can be found inmany applications all over the internet.
> 
> What is important is that the feed-backto the thermistor bridge (R+C) is selected for a proper timeconstant so that the regulation does not thermally oscillate.
> 
> The thermal delay between the mechanics/heat dissipatingcomponents and the isolation resistance between the thermistorand chassis is also important.
> 
> 
> All the best
> Ulf KylenfallSM6GXV
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