On 3/10/2016 7:43 AM, Ralph Mowery wrote:
"mike" wrote in message
...
I have an Ungar 9911 soldering iron handpiece
without the controller. Looks new.

I thought it would be trivial to build a temperature
controller.
I can make it hot. There is some PTC going on
as the current goes down as the iron heats up.

I expected some feedback.
The only other connector pins that have some
connectivity measure 497 ohms independently of
temperature. Can't use that for temperature monitoring.

Google has failed me.
Anybody know how these work?


After a quick search here is some info I found. Seems that there is no
feedback for the iron.

On 3/25/2013 10:58 AM, Wild_Bill wrote:
If you take the plug apart on the Ungar soldering iron cable (not fun),
you'll see there is a mini variable resistor inside the plug.. no sensor
used for the iron, in case I forgot to mention that.

The variable resistor is used to set/match the iron temp to the chart
supplied with the soldering station (so all the models have some
consistency when set to lowest to highest temp settings).



Thanks for all the thinking outside the box...
The calibration resistor seems like the most likely scenario.
There is some PTC. If I cool the tip, the current goes up somewhat.
Looks like all I need is a variable voltage source.
Where'd I put that box of old laptop power supplies???
It gets hot enough to melt solder on 12V, but haven't determined
whether it puts out enough heat to do real soldering work at 12V.

As for the IR sensor, yes, that's done.
I have some industrial grade hot air handpieces that have a sensor
outside the air path pointed at the heating element.
If you restrict the air flow, the element glows brighter for an instant,
then throttles back.