Sunday, December 9, 2012

Hakko FX-888 (220V version) LED Hack

(c) EEVblog

As seen in Dave's EEVBlog, there's a quite handy hack to help you realize if your soldering iron is turned on or not by replacing the original LED with a bi-color two-legged LED.

Circuit being basically the same designed by Dave, my version features a small board with a cable extension to the LED.

It's a very simple project, check out the schematics below for the 110v version of the soldering station:

Fig 1. Schematics for the 110v version connected to the Hakko microcontroller open collector driver

Instructions for the 220v version of the FX-888: 

The 220v version happens to be different than the 110v version as it lacks of a microcontroller with an open collector driver. It actually has analog components (some Op amps and an opto isolator to drive the triac).

In this case, you just need to add a general-purpose opto coupler (2N36) as follows:

- Feed the opto coupler with the LED pins.
- Use the open collector of the opto coupler as a driver for the Dave Jones' version of the bi-color LED circuit.

Fig 2. Schematics for the 220v version connected to the original LED terminal

Mounting instructions:

Red and black wires are coming out from where the original LED was and they feed the optocoupler.

Ground terminal for the blinking circuit is taken from the negative side of the big capacitor, with easy access through the large resistor. The other end of this same resistor will be used to feed the Vcc line. There is a 10v voltage drop at this resistor.

The completed project working. The result is the exact same result you will see in the video below.

Now look closer. See how I covered the high voltage section with Gorilla tape while working? That's what smart people do. Please be careful when testing your circuit with the case open as 220VAC can kill you, or someone else -your cat included-.

Even simpler would be to drill a small hole on your iron and add a second LED hooked up to any Vcc point you may find on your board, just as I did with my old Atten station a couple of years ago, addressing the exact same LED issue.

And this is the original video with -as always- a great explanation from Dave Jones. Thank you Dave.


  1. Hey Rod! where did you buy your 888? just trying to work out if the one I have is fake.

    And thanks for the post And to Dave of course :)


  2. Hi Andrew.

    I got it from DealExtreme. They label it as genuine, and it looks like it is: everywhere from the packaging to the manual, to the laser engraving in the tip that came with it. All except for the lack of the micro on the board. I think you and I are on the same boat and I guess it will be hard to know for sure if these are genuine unfortunately...

  3. If the board is different from the real Hakko FX-888; it is the indication that it is a clone. The chineses are pretty good at copying boxes, warranty cards, laser engraving etc.

    1. Very true unfortunately. I really was hoping for an original item when I bought it.