diy soldering station question

[mahyar]

so im building myself a soldering station based around a yihua 907a (a hakko 907 clone) and i have a slight problem i can't find any info about what kind of temperature sensor it uses some say its a type k thermocouple but others say its not.
so do any of you guy have any info about it? or perhaps its datasheet?

[Psi]

Well you can measure it with your meter to check if it's a thermistor (resistor) or not.

This seems to imply the Hakko is a thermistor
https://gw4sae.wordpress.com/2018/01/01/hakko-907-soldering-station-controller/

The thermistors i've worked with were all around 10k @ 25C
But that URL seems to say "52R at 22°C and around 130R at 500°C"  But i've never seen one that low before

[xavier60]

"A" version is supposed to mean it has a genuine Hakko heater element with a PTC thermistor starting at about 48Ω.

[mahyar]

Well you can measure it with your meter to check if it's a thermistor (resistor) or not.

This seems to imply the Hakko is a thermistor
https://gw4sae.wordpress.com/2018/01/01/hakko-907-soldering-station-controller/

The thermistors i've worked with were all around 10k @ 25C
But that URL seems to say "52R at 22°C and around 130R at 500°C"  But i've never seen one that low before

its still not here i've ordered it but it hasn't arrived yet

[Simon]

It sounds like the thermistor is the heating element. If these are 110V that sort of resistance will use the rated power of the heater especially considering that it will be PWM controlled anyway.

[mahyar]

"A" version is supposed to mean it has a genuine Hakko heater element with a PTC thermistor starting at about 48Ω.

thanks!

[mahyar]

It sounds like the thermistor is the heating element. If these are 110V that sort of resistance will use the rated power of the heater especially considering that it will be PWM controlled anyway.

they have seperate wires from what i know
and its a 24v iron rated 50w so i'd doubt the thermistor and the heating element are the same

[Simon]

I see, maybe it's something like a constant current source into the thermistor that generates a voltage like 5V for the control system then.

[xavier60]

If it really does use a genuine Hakko heater, its resistance is PTC also. A quick measurement on mine gave a reading of 3.5Ω cold to 8Ω
 hot. It can be an issue for an SMPS.

[mahyar]

well i just watch some teardown of a station that comes with this iron it seems like it is a thermistor thanks everyone

[mahyar]

If it really does use a genuine Hakko heater, its resistance is PTC also. A quick measurement on mine gave a reading of 3.5Ω cold to 8Ω
 hot. It can be an issue for an SMPS.

btw where did you read that "A" in the name means it has a genuine element?

[xavier60]

If it really does use a genuine Hakko heater, its resistance is PTC also. A quick measurement on mine gave a reading of 3.5Ω cold to 8Ω
 hot. It can be an issue for an SMPS.

btw where did you read that "A" in the name means it has a genuine element?

I used to see it mentioned in ebay listings.

[xavier60]

"Japanese Heating Element"
https://www.ebay.com.au/itm/154740714321?hash=item240743eb51:g:xoQAAOSwRWdhf5Rr

[xavier60]

"Japanese Heating Element"
https://www.ebay.com.au/itm/154740714321?hash=item240743eb51:g:xoQAAOSwRWdhf5Rr

It shows a 907D handpiece in that listing. I'm not so sure what the 907A is now.
 

[lscw]

I don't know about the varieties available but mine was one of the cheapest iron+air stations on the market about 18 months ago. So whatever the cheapest of the cheap use..

The heating/temperature sense parts of the circuit remain pretty much unchanged. I couldn't tell you what voltage the micro was reading for any given temperature other than 0-5V. I'll add the trimmer resistor values next week when I return home.

Schematic:
https://www.eevblog.com/forum/eda/my-first-pcb-(schematic)/

[xavier60]

I used a 907A soldering iron handle (much like ht eone described in this BigClive video, which is rated for 24v 50w. This handle also uses a thermocouple as a temperature sensor

http://electronics.vlzqz.com/home/lm324-analog-soldering-station

I bought my 2nd one of these recently, https://www.oritech.com.au/hakko-fx888d-soldering-station.html

[RayRay]

My opinion, you're wasting your time with this one (and I'll tell you why) with the original hakko 936/926 stations, the heating element matches with the original tips quite well (making excellent heat transfer) but with the knockoffs (non original element & tips) it's exactly the opposite, making poor heat transfer, which will cause you much frustration when using it! You're better off purchasing a T12 diy kit, or a pre-made T12 station even. In terms of cost/value, they rock, and with T12 tips having the heating element integrated, it makes a huge difference, and you'd never have to worry about replacing a fried heating element again!

[magic]

I don't believe you will get a genuine Hakko heater in any of those irons.

IIRC 907F was supposed to use an accurate clone of the Hakko A1231 heating element: ceramic heater (3Ω cold, increases with heat) and thermistor (tens of Ω).

A1232 is a heater using nichrome wire (~18Ω) and type K thermocouple. Widely advertised as 50W but do the math and you'll see it's 30W only if you are lucky and the transformer doesn't sag under load (and good luck with that in those cheapo stations). My handle with that thing was called 907I. It's longer than A1231 so those handles can't be upgraded with A1231.

A1233 is a heater using nichrome (~10Ω) and type K thermocouple. That one can do 50W on 24V power. IIRC same length as A1321 but not 100% sure. Incompatible with A1321 stations anyway due to different sensor. I would suppose 907A may likely contain that.

Somebody (Atten?) also made similar stations with two-wire heaters. I don't know how they work but two things come to mind: monitoring the heating element's thermal coefficient of resistance or putting a thermocouple in series with it. Either way,  temperature is measured during short periods when power to the heater is off.

[mahyar]

I don't believe you will get a genuine Hakko heater in any of those irons.

IIRC 907F was supposed to use an accurate clone of the Hakko A1231 heating element: ceramic heater (3Ω cold, increases with heat) and thermistor (tens of Ω).

A1232 is a heater using nichrome wire (~18Ω) and type K thermocouple. Widely advertised as 50W but do the math and you'll see it's 30W only if you are lucky and the transformer doesn't sag under load (and good luck with that in those cheapo stations). My handle with that thing was called 907I. It's longer than A1231 so those handles can't be upgraded with A1231.

A1233 is a heater using nichrome (~10Ω) and type K thermocouple. That one can do 50W on 24V power. IIRC same length as A1321 but not 100% sure. Incompatible with A1321 stations anyway due to different sensor. I would suppose 907A may likely contain that.

Somebody (Atten?) also made similar stations with two-wire heaters. I don't know how they work but two things come to mind: monitoring the heating element's thermal coefficient of resistance or putting a thermocouple in series with it. Either way,  temperature is measured during short periods when power to the heater is off.

thanks!
i won't be using one those cheapo stations i just got the handel and i'll be making my own station i already have most of the parts and it will end up cheaper than buying one also it will be a lot better in dozens of ways