My DIY soldering station - Page 1
Forum section: electronics / projects

author: Visher
author_rank: Contributor
timestamp: March 04, 2016, 11:11:30 pm
content: Hello everyone, this is my first post there which makes me glad to join your communityOver two months ago I started working on my project (guys, do you know that feeling when it's Christmas Eve and all of a sudden you realized that you want to make a DIY soldering station and you can't stop thinking of it?), the aim was to make a solder station which I was leaking of and teach myself a lot of new things with especially analog electronic (till 1 year ago I was fully into high-level programming on PCs and smartphones).The very first thing I did is I choose proper (at least I think so) soldering iron, it took few hours to dig into their specifications and do some compartments. Finally I came with a soldering iron from Solomon SL30 ESD-CMC for 50 PLN (4,3 PLN = 1 EUR, so 11 EUR / 13 USD) which did pretty good impression on me (and that was the first day I realized that electronics things with "ESD" in name are my catch-phrase like "sugar-free" for someone else etc). If you want, here's a quick look how does it look like inside:More specs: it's a 24 V iron with thermocouple inside heater, 48 W, up to 480 Celsius degrees, ESD-safe, ceramic heater, 5-pin connector (TC+, TC-, GND, HEATER-1, HEATER-2).The next problem for me was a power source. I found few toroidal transformers, however every single one was 12 V. I decided to unwound secondary winding and rewound it by myself, using galvanized wire from some kind of DC motor. I created two separate 12 V windings that could be connected in series to give 24 V:Next part of the project was the digital and analog circuity prototyping, I'm already familiar with AVR microprocessors and I decided to use ATmega16 due to 16 KB flash memory that is required to handle pretty large 128x64 LCD controlled by ST9720 driver, with using of u8g library. Little quick showoff how it was looking:Some mess around, as big as my personal life was consumed by this projectAt this moment, let's have a little stop and discuss few things. I've created working prototype, however I definitely wouldn't call it fully successful. I made several design mistakes, especially thermocouple circuit - there is no cold junction compensation and there are multiple different metals - soldering station's socket&plug, ARK connector. Also, there is 620 Ohm resistor pulled to opamp's non-inverting input to compensate opamp's offset voltage. That one possibly creates a voltage divider with thermocouple's wire, which is definitely not good.Why wouldn't I spend more time on improving it? I could work in this project for months improving every single thing, making it closer to perfect. However, I lack of good quality measurement tools, and time. Also I'm still a beginner in electronics who is keeping developing as fast as lack of good measurement and production tools can limit me. I wanted to finish this project and go with another one.Anyway, there's schematic and two-layer PCB layout. I did some PCB projects in past like motion-sensitive LED tape dimmer or accelerometer interface, and several others - so this one was pretty big for me.IMPORTANT NOTICE: LM7805 capacitors was 1000 uF and 470 uF, not 2x 4700 uFThe production process was most entertaining thing for me, I pretty really enjoyed it. I used thermotransfer method and etched a PCB in sodium persulfate. Before it was etched, I had to drill drills because of my drill is very cheap one () and keeps bursting thin etched tracks. Especially with 0.4 drills that I've used..Here are some pictures of production and assembly. I used case from broken ATX power supply to place components in:Translation of screen content:Soldering station v1Target: 170Temperature: 164Current power: 30 percConsumed current: 635 Wh(total) Work time: 12 hoursand current hour with ambient temperature - I put RTC in this boxI think that's all guysThanks for reading and feel free to comment, I'm open for suggestions. Don't blame me so muchYours,Adrian

author: rwgast_lowlevellogicdesin
author_rank: Frequent Contributor
timestamp: March 04, 2016, 11:50:56 pm
content: Awesome project!!! I always wanted to do this, never seem to have the time finally caved and bought one.If you would like to fix the thermocouple Maxim makes a chip that will accurately measure K type couples, which can be sampled for free and adafruit sells it on a breakout board I believe. I think MAX6675 may suit your project, seems that they acually make a few K type to digital chips, Im not sure which is the really popular one but I am sure if ada fruit has a break out they have a library for it too!

author: crispy_tofu
author_rank: Super Contributor
timestamp: March 05, 2016, 02:48:38 am
content: Wow, that is very cool.

author: Visher
author_rank: Contributor
timestamp: March 05, 2016, 11:53:00 am
content: Quote from: rwgast_lowlevellogicdesin on March 04, 2016, 11:50:56 pmThank you, I was aware of that kind of ICs (designed for thermocouples), however I decided to learn something about opamps as I never used them before in my life. Next time I'll consider buying such a module.

author: KL27x
author_rank: Super Contributor
timestamp: March 05, 2016, 12:30:00 pm
content: Nice work.

author: RobertGogol
author_rank: Unknown
timestamp: March 06, 2016, 09:18:01 am
content: Well done!Diy soldering station like diy power supply - stip learning curveI especially like using big LCD with mega16 - I must try to do it.

author: blacksheeplogic
author_rank: Frequent Contributor
timestamp: March 06, 2016, 09:51:04 am
content: Really impressed you had not only the thought but made it happen as well.

author: rwgast_lowlevellogicdesin
author_rank: Frequent Contributor
timestamp: March 17, 2016, 07:39:15 am
content: I may like to duplicate this station!!When I first go in to the hobby, before it became consulting and researching areas I dont particularly care about I had looked at a few DIY stations, they all turned me off because they used pics, and well my only pic programmer is a serial velleman kit that works with 16 and some 18 series pics, and not even the 18x that do USB beghh... At the time I only knew Parallax BS2, Propeller, and the Arduino environment with some lower level knowledge that allowed me to ditch some slow Arduino libs.Today when I get fortunate enough to not build projects based on 95% analog circuits I still enjoy the 8 Core Propeller (now with PASM), The AVR/Arduino mix with as little C++ as I can manage and the ARM family on Cypress PSOC. I think a Cypress with its programmable gain amps flexible adc's and a cold junction max chip would make the beginings of a GREAT hardware foundation for accurate PID loops plus many other features you could cram in the station, lol how about a quick adjustable square/sine wave out jack... IDK maybe that a bit of course:).I have a few questions of my own, if I wanted to build your project as IS then maybe tinker later I would like to understand why you made the decisions you did?First off props on the AtMega16, I have a few around from an old Logic Analyzer I built. But why did you choose the 16, was a 40 pin package necessary or did it meat some combo of peripherals a smaller atmega328 or attiny45 couldn't cope with? I get the use of opamps on the thermo couple.. reinventing the wheel is the only way to learn sometimes, hence why I use ASM and despise C++, there is no learning about the bare metal! I own a cheap sparkfun station wich is just an Atton 907b or something.... so I would be picking the max IC as my goal would to be make something I couldn't afford from JBC, etc.I think the solomon handles are the same as elenco (maybe i am really wrong) but there stations arent to much. Besides accurate PID the biggest difference is a station (discounting facy enclosure and iron holder) is the actual iron itself! I have a hakko 936 knock off handel somewhere and I experimented with it and a 24v transformer along with a Triac. I think these are 5 pin handles and Im not sure but If I remember correctly they don't use K couples the use a PTC or something to sense heat? The handles are all over for 7 bucks so why not choose one of those, was it all about the K thermo?The Atten I use now which is a 936 analog know off uses some weird 7 pin connector..... not even sure why! I cant replace the element have to get a new handle beghhhh. If I were to make a station I would also like to use an Iron with a K couple, since max make reading them along with cold junction compensation trivial and accurate. The thing is I would like to use a handel that is HIGH QUALITY and does not break the bank. I would also like to be able to order and identify the the connectors it uses.... soldering iron handels dont use standard din spacing so Im not sure what the heck. I think a Quality JBC or MetCal would cost quite a bit though... so what are some good handles out there using a k junction that are somewhere between the newer Hakko's and the JBC/METCAL I think $50 dollars for a solid handle an 20 for maybe 2 or 3 tips is about where one should be if wanting to homebrew quality and keep the parts (not including enclosure) at 150 or under.Heck I have an old unopened seed studio 2.4 inch touch screen I got on RShack liquidation for 8 bucks begging me to make a fully digital station or precision power supply. While I may be good with analog I just don't have good enough equipment that is in calibration to make a 5uV/5uA steppable PSU so a 70 dollar Korad is probably better than what I could build at that price in terms of PSU.I think this soldering station is great, im jealous I cant 3D print (not even a maker space around) a rad case like the OP, but I would like to hear some input on Decent transformers and Iron Pencils for a hi quality DIY stations (names and suppliers of the connectors would be just more than I could hope for), since that is what will really make the functionality stand out, maybe even some touch screen apps where you have solve weird puzzles with birds in order to raise the stations temp!!To the OP I use the heatless transfer method with nos issues at all I noticed there were pics of your boards, for some reason pics never scale right for me only PDF's. Would you mind posting the original CAD files or even correctly scaled PDF files? I may hook this to a 936 handle and do some learning about reading PTC sensors with opamaps! Hell the 5 pin hakko wont fit in my 7 pin Atten so IDK what else I would ever use a 7 dollar clone handle for,