Ungar 9911 soldering iron info?

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?

Reply to
mike
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Any inductance with the 497R ? perhaps a small relay in the handle

Reply to
N_Cook

Probably it's a diode, and an auto-ranging DMM showing forward voltage not resistance.

e.g.

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Try reversing the test leads?

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Adrian C
Reply to
Adrian Caspersz

Diode would make an excellent temp sensor, but you would have it right at the duty end, for minimum time-lag, are there high-temperature diodes ? or a way to have a fast-response normal diode set in a thermal-conductance scaled-down insulated sub-housing?

Reply to
N_Cook

Just got me thinking. Is there a soldering iron control system that uses an IR pyro sensor , set well back in the handle , in sight of but can monitor the heater block from afar?

Reply to
N_Cook

Yes, I started thinking that after posting. Who knows?

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Adrian C
Reply to
Adrian Caspersz

The problem with soldering iron control is putting a temp sensor in the heater block , if you can get away with simple heater and replaceable tips only, keeps the costs down (and swapping-out universality up , for hacker types). Ah so no manufacturer would want that. Another thing to try out sometime as a proving exercise.

Reply to
N_Cook

After a quick search here is some > If you take the plug apart on the Ungar soldering iron cable (not fun),

Reply to
Ralph Mowery

With an ordinary optical BPW21 photodiode with 18Meg resistor and DVM over it, in a dark room, a good regular 10mV range bewtween on and off of a magnastat iron with the window 1 inch from the barrel. So could easily make a highly responsive temp-controlled iron with simple heater and tips, what is drift like of photodiodes?

Reply to
N_Cook

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.

Reply to
mike

Most common conductors except carbon will increase the resistance when hot and lower it when cold. When you cooled the tip , the resistance got lower so the current went up. If designed correctly, most simple heaters are sort of self regulating as to the temperature of the heating element provided the voltage feeding it is constant.

I think I saw the voltage for the 9911 was 24 volts for the maximum designed heat output.

Reply to
Ralph Mowery

** Diodes have a strong negative temperature co-efficient, about -2mV per C for silicon types. Plus cannot tolerate temps above 200C at all.

.... Phil

Reply to
Phil Allison

** It is possible to use the rise in the resistance of the heater element as a temp sensor - but not so simple in a unit that claims to use zero crossing switching for power control.

My Hakko FX888 ( 24V, 70W) has a heater that measures 3ohms at room temp rising to 9 ohms at soldering temp. A feedback winding on the heater unit measures 47 ohms at room temp rising to 140 ohms at soldering temp - this is what control the tip temp.

.... Phil

Reply to
Phil Allison

Check out a Metcal. The heater element IS the temperature sensor. I've been using one for 15 years and wouldn't have anything else.

Reply to
stratus46

I was aware of them , when they first came out. Just checked the price of them and they will stay in the suppliers. My magnastat came from the one-time Ferguson site at Gosport , with 1986 melted into the plastic by "Jane" on the production line. I've worked out a simple way of making my own magnastat tips and if the element failed, have a reasonable chance of making my own heater (assuming by then replacement heaters will be unavailable).

Reply to
N_Cook

Just tried a 3mm LED sized, Telefunken S273P phototransistor on DVM-R and showed regular follower 1M to 1.5M variation 1 inch from switching magnastat iron barrel

Reply to
N_Cook

I'd like to hear more about how you make the magnastat tips.

I'd have to agree about Metcal. Best I ever used. I picked up a big handful of tips at a swapmeet. If I ever find a free Metcal station to plug them into, I'm in business. I thought about using a ham radio transmitter, but that seemed like overkill.

Reply to
mike

details on one of the tips (in other sense) files off

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Reply to
N_Cook

e
r

me

been using one for 15 years and wouldn't have anything else.

New Metcals are definitely pricey but used ones can be had for a reasonable price. Power unit around $50, new wand is $100, add a $25 tip and you're s till under $200. Over the years I've picked up over a dozen used ones for e mployers and friends. Two power units had failed and both were easily repai rable. One Metcal is at work and it gets used 10-20 hours per week. My oth er Metcal is at home and is used much less but i don't like poor tools. I o wn 2 Weller magnastats but don't even pull them out of the garage any more.

Reply to
stratus46

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