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Soldering station information request

123mmm

Member
Hello,
I have a Gordak soldering iron and I want to build a circuit to control this soldering iron.
I chose the attached schematic.
Unfortunately, I did not found the needed triac at the store (TR1).
1. What substitute do you recommend for this triac ?
2. Does R5 protect the soldering iron from overheating if the thermocouple is accidentally disconnected ?
 

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Last edited:

Nigel Goodwin

Super Moderator
Most Helpful Member
Hello,
I have a Gordak soldering iron and I want to build a circuit to control this soldering iron.
I chose the attached schematic.
Unfortunately, I did not found the needed triac at the store (TR1).
1. What substitute do you recommend for this triac ?
2. Does R5 protect the soldering iron from overheating if the thermocouple is accidentally disconnected ?
A TIC206 is a VERY, VERY common small plastic thyristor, if your store doesn't keep it then they probably don't keep any at all, order it on-line.

You are correct about R5, it turns the element OFF if the thermocouple goes O/C.
 

123mmm

Member
1. Assuming that I have a new schematic, can R8, R7 be safely replaced by 3k3 and R19 be safely replaced by 2k2 ?
2. What is the functionality of IC1B, in the attached schematic ?
 

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Last edited:

Nigel Goodwin

Super Moderator
Most Helpful Member
1. Assuming that I have a new schematic, can R8, R7 be safely replaced by 3k3 and R19 be safely replaced by 2k2 ?
Yes.

2. What is the functionality of IC1B, in the attached schematic ?
No idea, it's output isn't going anywhere, the only thing I can imagine is that it's used as thermal feedback for the entire IC, bearing in mind they are all on the same chip of silicon. Or it's a rather silly method of getting rid of the unused fourth opamp? :D
 

123mmm

Member
Does the above schematic have protection for soldering iron overheating if the thermocouple gets accidentally disconnected ?
 

123mmm

Member
I built the attached schematic, and I made a PCB by copying the pcb from the image. I found that it works. I used a Gordak soldering iron

I set the maximum temperature from W2 (approx. 8-9mV) and the minimum temperature from W4 (approx. 19.5mV). Is that correct?
 

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123mmm

Member
Does anybody know which trimmer is for setting the minimum temperature and which trimmer is for setting the maximum temperature ?
 

123mmm

Member
Does the schematic has a power off mode for the soldering iron when the thermocouple voltage rise above a certain value ?
 
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123mmm

Member
Hello,

I built the attached schematic and I wanted to find if the TL431 oscillates, using an oscilloscope.
I tested by connecting the ground probe to the 220uF capacitor ground and the detachable hook to TL431 catode.
The measurements were made when the soldering iron was connected into the circuit.

Can you please explain if there are oscillations in the screenshots ?
 

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