Poor man's Solder station

[onoffman]

Size is not a problem , cost want to keep low

So will start with nichrome heated solder bit as Iron.

>open the handle drill and put a thermistor
>replace cable with cutpiece 4in1 wire cable ..best will be cut a USB cable

This arrangement will get us the temp. data from the thermistor
After this some opamps to give 6ranges of temperature
and finally the controls
1) twin pole rotary switch
2) Fancy range indicator with backlit glass
The glass will have screen printed ranges and backing SMD LEDs

Doubt is there is thermocouple used in REAL stations
will this work yes will little limitations ?

Please suggest schematic

 

[Audioguru]

My Weller soldering iron is temperature controlled. The rear end of its tip has a special iron alloy piece and inside the barrel near this iron piece is a moveable on-off switch activated by a magnet. When the tip is cold then the special iron alloy in the tip is attracted to the magnet and the switch turns on. When the tip reaches a certain temperature set by the special iron alloy piece then the iron piece is not magnetic anymore then a spring lets the switch turn off. When it cools a little then the iron piece becomes magnetic again and the switch turns on again. It turns on and off all day. It is always at the correct temperature for soldering.
When I begin to solder something large then it cools a little then turns on full blast (60W) until its temperature is correct then it turns off until it has cooled a little.

The temperature is changed by changing the tip to one that has a different special iron alloy at its rear. I tried a cooler tip and a hotter tip 48 years ago and have used the middle temperature tip ever since.
Because the temperature is controlled then the tip never corrodes, the rosin in the solder never burns into carbon, all the solder joints are perfect and take about 1 second of time each to do and the tip lasts for years.

 

[D.A.(Tony)Stewart]

In old days, soldering experts only needed 35 W iron with a dimmer control to set temp. And we're able to perform NASA qualified soldering with correct tip size to match the part. Experience tells you if the solder temp is correct. Too hot oxides too fast, too cold is too slow. 3 seconds is all you need with proper technique. Cheap. That was the 70's.

then in the 80's has tips with bi-metallic switches inside so tips were numbered. 600'F was standard, but you could get others with screw in tips from Weller. In the 90's everyone had digital temp. Control. some used the best kind with RF surface regulated temp. Metcal, but $$.

 

[onoffman]

Thanks for the history.....

Now question still remains thermistor based turn on/ off may do the job or not ?

I have a feeling 'why not'

 

[dick_freebird]

Thermistor alone, will not do it. The resistance will dwarf
the heating element most likely and the heat will go to
where you don't want it. You would have to add some
signal conditioning and a power switch.

I've gotten my last several solder stations for free, Weller
and Metcal; companies dump anything that needs repair,
the Metcal (a great unit) only needed its power switch
replaced.

So my advice to you is, forget inventing and start
scrounging.

 

[onoffman]

Thermistor alone, will not do it. The resistance will dwarf
the heating element most likely and the heat will go to
where you don't want it. You would have to add some
signal conditioning and a power switch.

I've gotten my last several solder stations for free, Weller
and Metcal; companies dump anything that needs repair,
the Metcal (a great unit) only needed its power switch
replaced.

So my advice to you is, forget inventing and start
scrounging.

I meant on off all will be there ..but simple circuit to do that .
getting scraped unit is zero possibility .
https://www.youtube.com/watch?v=dA97AWkvwWI

 

[chuckey]

Modifying mains soldering irons should not be undertaken by amateurs, likewise having "ordinary" cable in the presence of high temperatures could lead so very unexpected results, also there is an on going problem of the flexibility of the cable its self.
The soldering element has its own temperature coefficient, so if you use DC to power the iron, you can inject AC to measure the resistance of the element, and hence control the DC or just read the temperature. The iron could also retain its original power plug and lead.
Frank

 

[colin55]

"My Weller soldering iron is temperature controlled."
No wonder you have absolutely no electronics ability.
Weller stations are the worst in the world. They have absolutely no ability to provide the correct temperature. I threw mine out 40 years ago.
This is more proof that you should not be giving advice on the web.

 

[onoffman]

no personal fights please .
chuckey
-excellent idea

please give links if there is any for circuit.


USB cable are very sweetly flexible also easily available .As long as iron is OFF and parts are insulated all can make mod my be believe.

 

[chuckey]

Is USB cable rated for mains voltage operation?
Frank

 

[onoffman]

Is USB cable rated for mains voltage operation?
Frank

No not i suppose the amps will not cross till 40Watts iron ?