VFD Puts the Suck Back into Desoldering Station

A dedicated desoldering station is a fantastic tool if you’re in the business of harvesting components from old gear. Having heat and suction in a single tool is far more convenient than futzing with spring-loaded solder suckers or braid, but only as long as the suction in the desoldering tool has a little oomph behind it. So if the suction on your solder sucker is starting to suck, this simple VFD can help restore performance.

Luckily for [Mr. Carlson], his Hakko 470 desoldering station is equipped with an AC induction motor, so it’s a perfect candidate for a variable frequency drive to boost performance. He decided to build a simple VFD that boosts the frequency from 60-Hz mains to about 90-Hz, thereby jacking the motor speed up by 50%. The VFD is just a TL494 PWM chip gating the primary coil of a power transformer through a MOSFET. Duty cycle and frequency are set by trimmers, and the whole thing is housed in an old chassis attached to the Hakko via an anachronistic socket and plug from the vacuum tube days. That’s a nice touch, though, because the Hakko can be returned to stock operation by a simple bridging plug, and the video below shows the marked difference in motor speed both with and without the VFD plugged in.

We’ve marveled at [Mr. Carlson]’s instrument packed lab before and watched his insider’s tour of a vintage radio transmitter. Here’s hoping we get to see more of his hopped-up solder sucker in action soon.

19 thoughts on “VFD Puts the Suck Back into Desoldering Station

      1. So which came first? VFD as in display or VFD as in drive? I am reminded of another incident where someone recycled 8mm without looking at the history. Now we have 2 different kinds of format that shares the common term 8mm. The old film that was started almost 100 years ago for home consumer use, and the magnetic 8mm tape also used for home consumer use about 30 years ago.

  1. That is a nice job and a good way to breathe new life in an old tool – they were using 60/40 or 63/37 solder everywhere at the time that tool was designed, which flows a lot easier. It does not surprise me that such a tool would need an upgrade to pull lead-free solder well.

    I am fascinated by Mr. Carlson’s equipment collection (i also like his calm voice and detailed presentation) and have been a subscriber to his channel for a while.

    On this particular topic, i went the “clever hacker on a shoestring budget” way. I purchased a cheap Chinese manual desoldering iron – it’s pretty much like the small crappy solder pumps but with a heated metal tip and a power cord… A while later i remembered i had a hot air station with a burnt heater which had been lying around for a few years, the kind that uses a diaphragm pump rather than a blower fan. I was able to modify the pump to draw air instead of blowing – a simple and reversible hack, no less! – then it was just a matter of mating the hose to the end of the former manual pump and getting a good seal. Next step was drilling an extra hole for the iron’s cord and patching that thru to the already existing on/off switch on the station. Finally, i added yet another cord going to a small push button on the iron to operate the pump, in the same location where the button to release the spring of the manual pump was. I was even able to use the same plastic button.

    The end result works quite well. The pump is strong enough to not require a VFD :) I do have another improvement planned which does involve rectified mains and PWM, but more on that some other time.

    I hope to publish the project sometime soon.

  2. I saw this and really got my hopes up. Then I pulled apart my Hakko 703, and it has a 24v DC motor on its vacuum pump. The 703 is all 24v DC, even the irons. Maybe all the Hakko irons are 24v, I do not know. This is the only soldering iron I have ever used. Where I used to work (and where I learned to solder), we had a Hakko 703 and I liked it so much that when they went out of business, I bough a 703 just like it off of Fleabay.

  3. You could get one of those eBay DC to DC converters and step the 24 up a bit. I have used the beefy ones to run windscreen wiper motets and the like at higher voltages. If you search 1200w DC converter a few should turn up.

  4. I just step harder on my foot bellows hosed to former spring loaded piston sucker iron. The piston chamber becomes the trap. Every so often I hold it upside down and tap it on the bench whilst sucking to keep it from clogging. The bellows is easy, I rebuild player pianos. Tough rubberized canvas will do. I should measure the vac. Will it over-range my 200inch water digital gage? I think it will, the rig really sucks.

    If it were butane powered it would be non-electric. Do they make such a thing.

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