diy soldering station question - Page 1
Forum section: electronics / beginners

author: mahyar
author_rank: Newbie
timestamp: December 24, 2021, 11:31:59 am
content: 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?

author: Psi
author_rank: Super Contributor
timestamp: December 24, 2021, 11:39:49 am
content: 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 thermistorhttps://gw4sae.wordpress.com/2018/01/01/hakko-907-soldering-station-controller/The thermistors i've worked with were all around 10k @ 25CBut that URL seems to say "52R at 22°C and around 130R at 500°C" But i've never seen one that low before

author: xavier60
author_rank: Super Contributor
timestamp: December 24, 2021, 11:50:42 am
content: "A" version is supposed to mean it has a genuine Hakko heater element with a PTC thermistor starting at about 48Ω.

author: mahyar
author_rank: Newbie
timestamp: December 24, 2021, 12:10:03 pm
content: Quote from: Psi on December 24, 2021, 11:39:49 amits still not here i've ordered it but it hasn't arrived yet

author: Simon
author_rank: Unknown
timestamp: December 24, 2021, 12:10:10 pm
content: 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.

author: mahyar
author_rank: Newbie
timestamp: December 24, 2021, 12:10:37 pm
content: Quote from: xavier60 on December 24, 2021, 11:50:42 amthanks!

author: mahyar
author_rank: Newbie
timestamp: December 24, 2021, 12:12:39 pm
content: Quote from: Simon on December 24, 2021, 12:10:10 pmthey have seperate wires from what i knowand its a 24v iron rated 50w so i'd doubt the thermistor and the heating element are the same

author: Simon
author_rank: Unknown
timestamp: December 24, 2021, 12:23:01 pm
content: 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.

author: xavier60
author_rank: Super Contributor
timestamp: December 24, 2021, 12:23:52 pm
content: 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 8Ωhot. It can be an issue for an SMPS.

author: mahyar
author_rank: Newbie
timestamp: December 24, 2021, 12:35:44 pm
content: well i just watch some teardown of a station that comes with this iron it seems like it is a thermistor thanks everyone

author: mahyar
author_rank: Newbie
timestamp: December 24, 2021, 12:37:59 pm
content: Quote from: xavier60 on December 24, 2021, 12:23:52 pmbtw where did you read that "A" in the name means it has a genuine element?

author: xavier60
author_rank: Super Contributor
timestamp: December 24, 2021, 12:59:25 pm
content: Quote from: mahyar on December 24, 2021, 12:37:59 pmI used to see it mentioned in ebay listings.

author: xavier60
author_rank: Super Contributor
timestamp: December 24, 2021, 01:02:01 pm
content: "Japanese Heating Element"https://www.ebay.com.au/itm/154740714321?hash=item240743eb51:g:xoQAAOSwRWdhf5Rr

author: xavier60
author_rank: Super Contributor
timestamp: December 24, 2021, 01:13:58 pm
content: Quote from: xavier60 on December 24, 2021, 01:02:01 pmIt shows a 907D handpiece in that listing. I'm not so sure what the 907A is now.

author: lscw
author_rank: Contributor
timestamp: December 24, 2021, 10:24:30 pm
content: 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)/

author: xavier60
author_rank: Super Contributor
timestamp: December 25, 2021, 05:03:38 am
content: Quote from: vlzqz.comhttp://electronics.vlzqz.com/home/lm324-analog-soldering-stationI bought my 2nd one of these recently,https://www.oritech.com.au/hakko-fx888d-soldering-station.html

author: RayRay
author_rank: Frequent Contributor
timestamp: December 25, 2021, 05:26:58 am
content: 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!

author: magic
author_rank: Super Contributor
timestamp: December 25, 2021, 11:51:02 am
content: 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.

author: mahyar
author_rank: Newbie
timestamp: December 26, 2021, 10:17:46 am
content: Quote from: magic on December 25, 2021, 11:51:02 amthanks!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