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Weller soldering iron: 24 VAC or DC

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Evalon

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Hello everyone,

A bit of advice is desired: I am considering building a soldering station e.g. for a Weller FE 50 or LR 21 soldering irons. I've noticed that Weller outputs 24 VAC from the soldering station to the soldering iron, however, can it be done so that it a suitable VDC is output instead? Or does the functional principle of the iron make this not feasible?

If any of you know of this I'd appreciate your feedback ...

Greetings,

Jesper Mønsted
 
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The power in a heater is exactly the same if the voltage is 24VDC or 24VAC.
If you make a 24VDC power supply then it needs a lot more parts than just a transformer that makes 24VAC.
 
Why would you want DC instead of AC going to the iron?
 
I don't know, maybe he wants to power his soldering iron from a couple of 12V SLAs in series?
 
The power in a heater is exactly the same if the voltage is 24VDC or 24VAC.
If you make a 24VDC power supply then it needs a lot more parts than just a transformer that makes 24VAC.

Hi audioguru & thanks for your reply. My question really was related to whether or not there is "something" in the soldering iron's design/construction that will either break it - or - not make it work with DC. That really is my question :) But if there isn't it's much more straightforward for me to move on with.

If one of you knows differently please comment ...

And, yes, I realize that DC construction may take more components - I will just be using it in a place where DC, and probably not AC, is available.

BTW - if I remember correctly - isn't it so that the DC power value for the same voltage is higher than the AC? The area under the curve of the AC (24 volts peak) will be less than the area under the DC curve...

Thanks again for your comment!

Regards,

Jesper
 
BTW - if I remember correctly - isn't it so that the DC power value for the same voltage is higher than the AC? The area under the curve of the AC (24 volts peak) will be less than the area under the DC curve...

What you are looking at is the heater gets 24 VAC RMS. Therefore that is the DC equivelent. Were you planning on temperature control or using the temperature sensor in the pencil for anything?

Ron
 
What you are looking at is the heater gets 24 VAC RMS. Therefore that is the DC equivelent. Were you planning on temperature control or using the temperature sensor in the pencil for anything?

Ron

I'm planning to implement a simple type of temperature control by using a comparator that switches a transistor on & off. I need to calibrate it, though, somehow.

But you reckon DC would work as well?

Best regards - Jesper
 
The transformer powering the soldering iron will be specifier in RMS, as mentioned above. The peak voltage will be 24√2 = 34V.

DC will work as well but I wouldn't bother myself. I would just power the comparator circuit from a half wave rectifier and use a triac to switch the soldering iron. The control circuit will be DC and the soldering iron still AC.
 
Hi again,

I think I know now what I need to know - thank you all for your inputs & suggestions!

The best for your weekend ;)

Jesper
 
Here's a rough schematic to get you started.
 

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