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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Putting the flex back into the RDS 80 soldering station

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[Markus] was looking to upgrade his soldering station, and having had good luck with Ersa in the past, opted to purchase one of their new stations, the RDS 80.

Once he got the iron home however, he was very disappointed to see that while his previous Ersa model used a silicone cable to connect the iron to the base station, his new iron used a stiff, non heat-resistant PVC cable instead. He found plenty of people complaining about the same issue online, but no one seemed to have a fix, so he set off to figure it out for himself.

He thought that he could disassemble the iron and change the wiring out once it was apart, but it seemed that there was no way of doing so without destroying it. Instead he chopped the wire off at the end of the soldering iron, replacing it with a new silicone cable. He did the same thing at the base station end, since he was forced to reuse the proprietary 4-pin plug Ersa decided to use there.

His modifications worked out nicely, and he is now happily soldering away.

If you happen to have one of these soldering stations, be sure to swing by his site to get a closer look at how he swapped out the cable.

Tools: Aoyue 968 3-in-1 soldering and rework station

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The $10 “fire-starter” is the most common beginner soldering iron. These are simple irons with a hot end, a handle, and little else. There’s no temperature control or indication. Despite their simplicity, they’ll do just about anything. You can solder any legged chip type with this type of iron. We used fire-starters in the lab for years.

Eventually, we wanted a hot air rework tool to salvage SMD parts and solder QFN chips. Aoyue is a relatively unknown Chinese brand that makes soldering stations very similar in appearance and function to Hakko. Aoyue stations are recommended and used by Sparkfun Electronics, something that factored heavily in our decision to buy an Aoyue. Read more about our experiences with this tool after the break.

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