Soldering iron station circut

[kulakovs]

Hi guys. I'm trying to build a temperature regulator for my soldering iron. In soldering stations, this voltage (temperature) regulator just consists of a triac, few capacitors and potentiometer. Can anyone recommend me a schematic for this purpouse? It would be nice if the circuit could control the voltage from 0V (or near that value) to full 220V ( Europe - 220V 50Hz) . Thanks.

 

[antknee]

A dimmer light switch would do the job.

 

[Sceadwian]

No it wouldn't antknee, a dimmer would allow wattage control not temperature control, believe me there's a big difference.
A temperature controlled soldering station requires a heat sensing component at the soldering element to provide feedback to a circuit that adjusts that duty cycle.

Why don't you buy a temperature controlled soldering station? Inexpensive units can be had for 40 dollars, the one I got from MPJA (model 301A) is ESD safe and comes with a very nice tip for general soldering work. Replacement handles are only 12 dollars.

 

[kulakovs]

Well the main reason isn't controlling the temperature itself, I just assumed that by controlling voltage you could control temperature too.

Imagine situation: I'm soldering something and I want to take a 5 minute break. If I leave my iron on, it would consume a lot of electrical power and it may burn out (cheap soldering iron). But if I were to leave the iron off, after those 5min I'd have to wait a few minutes till iron gets hot again. Lowering voltage to about 60V would certainly take care of all problems.

Back to topic. I don't know why but dimmer switches at my local shop are very expensive (more than 15$). Basicly I'm just looking for a dimmer switch schematic, so I could save some money.

 

[ericgibbs]

Well the main reason isn't controlling the temperature itself, I just assumed that by controlling voltage you could control temperature too.

Imagine situation: I'm soldering something and I want to take a 5 minute break. If I leave my iron on, it would consume a lot of electrical power and it may burn out (cheap soldering iron). But if I were to leave the iron off, after those 5min I'd have to wait a few minutes till iron gets hot again. Lowering voltage to about 60V would certainly take care of all problems.

Back to topic. I don't know why but dimmer switches at my local shop are very expensive (more than 15$). Basicly I'm just looking for a dimmer switch schematic, so I could save some money.

Why not just switch a series diode in/out of the irons AC supply.????

 

[kulakovs]

ericgibbs, if I got it wright that would make a 50% duty cycle, wouldn't it?

 

[ericgibbs]

ericgibbs, if I got it wright that would make a 50% duty cycle, wouldn't it?

That would be around 50% duty cycle.
Its quick and easy to try to see if it meets your requirement, just use a suitable volts/amps diode.

 

[MrAl]

Hi,

If simply lowering the power of the iron temporarily is all you want to do then i have to agree that a diode is probably the simplest way to get that to happen. The diode will cause a decrease in power of roughly 50 percent so the iron will cool down to a temperature of about 56 percent of the temperature at full power.
I would think a diode such as 1N4007 would work pretty well.
This wont be a good idea with the induction type soldering guns however, but i dont think you have that type.

 

[colin55]

A clever method is to detect the resistance of the element as this corresponds to the tip temperature.

 

[MrAl]

Hello colin,

I was going to try that actually, but when i calculated the resistance of my iron it only varied by 4 percent from room temperature to full power hot. That means it would vary very very slighly over say 2 degrees C near the hot temperature setting. Would require a very accurate circuit. I also have to wonder about the heat dynamics from element to tip.
Know any company that does this?

 

[Reloadron]

Hi Ya MrAl

I don't know of any company that publishes data on the thermal conductivity from the element to the tip but years ago I managed to become an unwilling participant in a program to initiate calibration methods and procedures for controlled heat soldering stations.

Most of the better made stations actually place the temperature sensor directly into the tip. Matter of fact well embedded into the tip for very good control of tip temperature. Calibration was performed on an unloaded tip using a thermocouple made up of AWG 30 TC wire to preclude the TC loading the tip. The tip was slightly whetted to afford good thermal conduction of tip to the TC.

As to Eric's mentioning using a diode. I once took apart an El' Cheapo Radio Shack switched 15 watt / 30 watt station when the 15 watt setting was too hot. They used exactly as Eric mentions. They switched a diode in and out of series with the element. The diode was shorted.

Over the years I also used a lamp dimmer which worked well enough but was also a trial and error method as depending on what you are doing there is no feedback to compensate for tip loading. Sceadwian covered that well. You really don't have control.

All in all I guess it really depends on what the end user wants or needs for soldering applications.

Ron

 

[audioguru]

My temperature-controlled soldering iron senses the tip temperature and adjusts it by turning on and off.
It can sit doing nothing for months and does not over-heat nor burn out.
It goes automatically to full power when I solder something that is big, then it maintains the proper temperature without over-heating.

 

[colin55]

All soldering stations with 2 wires to the tip plus earth, use the method to detect the resistance of the heater.

 

[MrAl]

Hi Ya MrAl

I don't know of any company that publishes data on the thermal conductivity from the element to the tip but years ago I managed to become an unwilling participant in a program to initiate calibration methods and procedures for controlled heat soldering stations.

Most of the better made stations actually place the temperature sensor directly into the tip. Matter of fact well embedded into the tip for very good control of tip temperature. Calibration was performed on an unloaded tip using a thermocouple made up of AWG 30 TC wire to preclude the TC loading the tip. The tip was slightly whetted to afford good thermal conduction of tip to the TC.

As to Eric's mentioning using a diode. I once took apart an El' Cheapo Radio Shack switched 15 watt / 30 watt station when the 15 watt setting was too hot. They used exactly as Eric mentions. They switched a diode in and out of series with the element. The diode was shorted.

Over the years I also used a lamp dimmer which worked well enough but was also a trial and error method as depending on what you are doing there is no feedback to compensate for tip loading. Sceadwian covered that well. You really don't have control.

All in all I guess it really depends on what the end user wants or needs for soldering applications.

Ron

Hello there Ron,


You da' man on this subject.

I had a feeling the better irons would use a TC probably in the tip as the conduction dynamics are going to be relatively slow along the tip. Even then, the element has to be extra heavy duty to be able to induce a change in the far away tip wiithin a reasonable time.
The equivalent electrical circuit would look like a variable DC voltage source (heat element) driving a low pass filter, with the output voltage being the tip temperature. Depending on the mass (heat capacity) the response time could be too slow.
A sensor farther up the tip might still work, but the effective temperature differentials decrease the farther we get away from the tip making it more and more inaccurate.

Thanks for the informed info there and nice talking with you again.

 

[Sceadwian]

For half power the diode idea works nicely, it also adds a lot of AC noise to the mains line, something that should be noted.

 

[Reloadron]

For half power the diode idea works nicely, it also adds a lot of AC noise to the mains line, something that should be noted.

Yes, and also back on topic around here a typical lamp dimmer is about $3.95 USD. The op mentioned in his location they cost much more. Here is a simple 220 volt mains triac circuit that should work.

Ron

 

[colin55]

Here is a typical soldering station circuit, from Silicon Chip:
**broken link removed**

 

[MrAl]

Hello again,


Interesting circuit colin, thanks for posting it. It does look like it suffers from the tip heat capacity delay, but might work good enough for many uses.
It's also interesting that it is using a 12v element. I have one of those around here somewhere i might be able to try this with. My other irons are all 120vac, but would most likely run on 120vdc too.

 

[kulakovs]

Thank you Reloadron for the schematic, I never would have found it myself. I'll try to build a light dimmer and a diode version and then decide which one works best for me.
BTW 3.95$ ? Even on ebay they cost around ~9$ (including shipping).

 

[tvtech]

Hey Guys...I thought to post this wee bit of info just in case someone tries it....

I use a Magnum soldering station made right here in good old South Africa. Kicks Weller into touch as far as reliability and performance is concerned.

The only...and I mean the only thing with this type of Iron is never to try and run it on DC or from an Inverter. Why?. Cause the irons circuitry uses "zero crossing" technology to control tip temperature.

And as we all know, DC has no "zero cross" point. Cause it's DC. Same with inverters that simulate AC.

The Iron will work for a while connected to either DC or an Inverter and then will burn out as all temperature control will be missing and the element will literally self destruct.

Cheers