I was interested in the TS-100 soldering iron as it seems to be popular these days. The heat on the soldering iron tip is controlled by an MCU and also it has a little display and buttons to change features on-the-fly. While relatively inexpensive, it does not come with a power supply, so either you have to use your own (if it has compatible connector) or you have to buy one. Also the power cord kind-of limits you the same way as the standard soldering iron.
Then I came across a cheap USB powered soldering iron ZD-20U which at the first glance looked more like a toy rather than a real soldering iron. I had a look at the youtube video by
'bigclivedotcom'
who seemed to be impressed by the capabilities of the iron, he took it apart, described the principles of how it operates and also produced a schematic. Another video made by
'TheStuffMade'
measured the heat temperature on the iron tip, and found it was too high (360 deg. C) to be used for electronics projects. The iron uses 555 chip to control on / off time of the iron. In the first video you can see the PCB of the iron and I've noticed the 555 chip uses SOIC8 package exactly the same as the ATtiny13a MCU I used on my ORB board. Then - inspired by the TS-100 iron - the idea struck me: let's replace the 555 IC by the ATtiny13 and control the heat temperature by the tiny MCU.
The iron is quite cheap and I bought one on ebay for 5£. I tried to use it as it came - umodified - and found out I can barely use it for several reasons. The touch sensitive stud did not work reliably with my hands. Often the soldering iron turned off and I could not turn it on by touching the metal stud. I had to shake the iron quite hard to trun it back on, and by doing that I lost concentration when soldering. Next thing I didn't like was the 25 seconds turn-off timeout. For my taste that's too short, so the iron turned off too soon and I had a hard time turning it on. Also you can NOT just press the stud to continue soldering, you have to wait till the soldering iron is off to turn it on again by touching the metal stud. On the other hand I liked it's powered from USB and is light and mobile when using power bank. Also the power cord is thinner (compared to normal desktop soldering iron) and overall it is more compact. So I decided to mod it and fix the issues I found. I've replaced the touch sensitive stud by a tactile button, and I can easily control the on/off time by the MCU without waiting till it's turned off. As a bonus feature I've added another LED indicator and use sigma-delta to adjust the temperature of the heating element. My goal was to use the original PCB with just a minimum changes, so the modification would be chap and simple. Of course, compared to TS-100, it is quite primitive but still improves the iron a bit.
The result can be found on
github here,
it contains the modification instructions and the MCU source code. The code has MIT license, so it's free to use and modify.
Let's list the new firmware / modded features:
After the RED blink, the GREEN led starts to blink. The number of GREEN flashes
indicates the profile value. After the GREEN flashes the iron expects the user
to press the button to select the value she desires. If a button is not pressed
within ~1 second the next value is presented (more GREEN blinks).
BTW. I found the manufacturer of the iron, it is Ningbo Zhongdi Industry&Trade Co., Ltd.
You can find their web site here:
www.china-zhongdi.com
Value 1: 32 seconds, value 2: 64 seconds, value 3: 96 secs, value 4: 128 secs
Value 1: 10 seconds, value 2: 12 seconds, value 3: 14 secs, value 4: 16 secs
RED blinks R times to indicate which profile is being set: