Ask Hackaday: What’s an easy way to build a potentiometer for a soldering iron?

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[Lee] wrote in to share the work he’s done in building a controller for his soldering iron. The idea started when he was working with an ATX power supply. He figured if it works as a makeshift bench supply perhaps he could use it as the source for an adjustable iron. To get around the built-in short-circuit protection he needed a potentiometer to limit the current while allowing for adjustments. His first circuit used a resistor salvaged from an AT supply and a trimpot from some computer speakers. That melted rather quickly as the pot was not power rated.

This is a picture of his next attempt. He built his own potentiometer. It uses the center conductor from some coaxial cable wrapped around the plastic frame of an old cooling fan. Once the wire was in place he sanded down the insulation on top to expose the conductor. The sweeper is a piece of solid core wire which pivots to connect to the coil in different places. It works, and so far he’s managed to adjust a 5V rail between 5A and 20A.

How would you make this system more robust? Short of buying a trimpot with a higher power rating, do you think this is the easy way to build a soldering iron controller? Let us know by leaving your thoughts in the comments.

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Laptop motherboard reborn as a low-wattage server

[Darknezz] sent us a set of photos and some details about his damaged laptop motherboard turned into a server. A client brought him a Dell 1525 on which nothing was showing up on the LCD screen. The HDMI and VGA still worked, and he traced the problem to no signal coming out of the motherboard. He swapped the board out to get the laptop working again, but he client said he could keep the damaged one.

It has a dual-core CPU which meets his needs and since it’s meant to run off of a battery it’s as energy-efficient as possible. [Darknezz] dug through his parts bin and found a PSU that could supply the needed 19.5V at 3.5A. The connector didn’t match but it didn’t take him too long to patch into it using a spare Molex connector. He also needed a power button and ended up soldering a momentary push switch to a couple of pads which he traced out form the original connector. The only thing he actually ended up purchasing were the memory modules. Check out the photos he took of the alterations in the gallery after the break.

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Dual-channel, variable voltage test box is a busy console modder’s dream

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It seems like [Chris Downing] is always up to something new. If he’s not keeping busy by creating slick portable iterations of previous-gen gaming consoles, he is dreaming up ways to make his modding life a bit easier.

Recently while working on a Nintendo controller designed to control three different consoles, [Downing] found his desk buried in a pile of power supply and A/V cabling. Annoyed with his growing rat’s nest, he decided to build a universal power supply that would allow him to quickly switch between consoles with little effort.

He dug up an old PC power supply, and fed it into a LED control box built for cars. [Downing] then mounted an array of nine rocker switches on the box, adding A/V inputs and outputs along the way. A set of voltage regulators hidden inside allow [Downing] to dial in whatever custom voltages he might need at the moment.

The test box should come in pretty handy as [Downing] pursues even more modding projects in the months to come. In the meantime, be sure to check out the video below where he covers the finer points of the device’s design.

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Giving an ATX bench supply the case it deserves

Your bench supply doesn’t need to look sad just because you’re using an ATX power supply instead of a commercial product. Follow [Ian Lee’s] example and you could have beautiful wooden enclosures for the tools in your own shop.

The woodworking skills used here aren’t all that advanced, but you need to have a knack for it so we suggest running some test pieces before you start the actual build. [Ian] ran a dado for the front and back panel in each piece of the wood sides. At each corner the inside of the the pieces were mitered at 45 degrees. To put it all together he laid the pieces end to end on a the work bench, then applied painters tape to the outside of the joints. This holds the joints together so that he can flip the collection over, apply glue, and then start hinging the sides into place. It’s almost like rolling up a box.

As with other ATX supply projects we’ve seen [Ian] designed this so that the PSU can be swapped out later if necessary. Instead of wiring his own cable harness he used an ATX breakout board. To get the interface layout he wanted he mounted the banana jacks separately and just ran jumper cables back to that board.

Repurposing server PSU for your charging needs

That grey box at the top of the photo is a modular power supply unit for a rack-mounted server system. [Sebastian] decided to repurpose it as a charging source for his RC batteries. He chose this HP DPS-600PB because of its power rating, efficiency, and you can get them at a reasonable price.

This is an active power factor corrected (APFC) PSU, which he says draws 40% less current than the non-APFC variety. Since he sometimes charges batteries in the field from a generator this is a big plus. But a bit of modification is necessary before it can be used as a source.

Since this is a rack device it has a set of connectors on the back. For power there are spade connectors which mate with a fin on the rack. He soldered positive and negative leads between the spades to interface with the battery chargers. The PSU won’t fire up if it’s not in the rack, so some jumper wires also need to be added connecting three of the interface pins.

With his modding all worked out he went on to use two PSUs for a 24V source, housing them to a nice carrying case while at it.

Bench supply built in a power strip

Back in his college days [Print_Screen] grew tired of always building a power supply on his breadboard. To make prototyping quicker he came up with the bench supply that is build into a power strip. This one is using linear regulators for power, and create much less noise on the lines than a supply made from a switch-mode PSU.

First thing’s first, he needed to step down from mains voltage and rectify the AC into DC. He gutted the smallest adapter he could find and managed to fit it into the gutted power strip. It puts out 15V which will work perfectly for the regulators he’s chosen. Each one gets its own slot where an outlet is on the case. The ground hole has been plugged by a toggle switch which routes power to the free-formed regulator/capacitors/heat sink modules. There is a slot for 15V (coming directly off of the converter), 10V, 5V, 3.3V, and two variable regulators which are controlled by the knobs above the outlet. We’ve never seen anything like this and find it most excellent!

[Thanks OverFlow636 via Reddit]

Building a bench supply without altering the ATX psu

[FozzTexx] has been using a bench supply he made from an AT PSU for years. He put a lot of work into that one, removing unnecessary wires, mounting banana plug jacks on the metal case, and adding an on/off switch and labels. But if it ever dies on him it will be a major pain to do all that work again in order to replace it. When he set out to build another bench supply from an ATX PSU he decided to do so without altering the PSU. This way he can easily swap it out for a different one if he ever needs to.

The hardest part of the hack was sourcing connectors. But with the parts in hand he’s able to just plug the faceplate into the stock connector. This gives him access to all of the voltages, and provides an on/off switch and indicator light. He might also want to add the option of resetting the unit if the over-current protection kicks in.