Analogue T12 style controller - anyone tried it?

[Agent24]

I see the "T12" stations are quite popular now, and what I found fascinating was this thread here: https://www.eevblog.com/forum/review...p)-conversion/ - which includes an analogue control circuit for the T12 cartridges.

Since I'm not really a fan of devices powered by undocumented microcontrollers, I'd rather have an analogue version - so much easier to fix (and cheaper).

Has anyone used this circuit? One user in that thread says it works well and many people have built one - but so far as I can see, most people just seem to go for the OLED etc versions with more flashing lights.

I'm quite tempted to build this controller and get a nice aluminium "Quicko" T12 handpiece for $20. Seems like a great deal - if it works.

[stj]

looks like bs, i cant see how it's using any tip feedback - it's just a variable current drive circuit.
to work properly it needs to pulse the tip really fast, and read back the sensor between pulses.

btw, there are open-source microcontroller based controllers you could make from scratch, or based on arduino/blue-pill

[Agent24]

From what I understand, it should basically work - unless I have interpreted it incorrectly.

U1B will drive Q2/Q1 on while C2 charges via R4, until C2's charge reaches about 1/2 Vcc, then U1B should switch the heater power off.

C4 (which would have charged up to 24v during heater power) will now discharge through the heater/TC until its voltage reaches the thermocouple voltage, and if that is lower than the voltage set by R2, U1A will go low and start to discharge C2 via D1, then the cycle repeats.

If the iron is hotter, and the thermocouple voltage is higher, then the charge on C4 will keep U1As output high, and U1B will stay off until the thermocouple voltage drops.

So in terms of temperature regulation and actually reading the thermocouple, I think it does do that. The question is whether or not it does it well.

[Agent24]

Well, perhaps that is how it is supposed to work.

But in https://www.eevblog.com/forum/projec...soldering-tip/ someone says he bought one and it did not function correctly.

They seem to think the main problem is no thermocouple amplification, and there are probably other issues as well.

Do you have any links to the open-source microcontroller versions?

[stj]

one with oled is on eev,
several are here:
http://dangerousprototypes.com/forum/viewforum.php?f=56

[Agent24]

Thanks, I'll take a look.