DIY Adjustable Power Supply Transformation Guide

Transforming an old adjustable power supply made from a voltage regulator module and an OLED display header, with a non-functional fan, into a usable device involves some modifications. Here's how you can repurpose this power supply:

You can try repackaging it into a portable adjustable power supply using 18650 batteries. Let's DIY together with this guide.

Start by 3D printing the casing for the adjustable power supply.

Materials Used:

Here are some close-up shots of the modules used: TP5100 8.4V 2A charging module. Since it requires an input voltage greater than 8.4V and consumes over 15W, a 12V QC, PD spoof was used, but its small size couldn't accommodate a banana socket, so the output was changed to a Type-C interface, which can also serve as an emergency power bank. Later, a Type-C to banana adapter will be made.

If one of the 18650 batteries fails during the process, causing the voltage to drop to 0V, a Samsung 2600mAh battery can be used as a substitute, though the internal resistance of the two battery types may differ, necessitating manual voltage balancing later.

Install two sets of lithium battery protection boards. For lithium battery soldering, flux can be used with low-temperature solder paste at 138°C; the soldering iron can quickly solder the joints.

Next, place the various modules inside. Secure the voltage regulator module with hexagonal nylon spacers and use silicone rubber for the other modules.

The TP5100 charging module generates a lot of heat due to its high charging power of 15W; applying a piece of graphite thermal pad can help dissipate heat.

If the nut is too high and prevents the installation of a heat sink, and cutting the heat sink is not desirable, a thick layer of thermal conductive silicone grease pad can be used as a solution.

Close the case; the heat sink should align perfectly with the top opening.

The switch has three settings: External Power Supply | Off | Battery Power. Regardless of the switch position, the battery will be charged by the PD, QC spoofer.

With a maximum voltage of 33V and a maximum current of 3A, considering the heat dissipation, the maximum output power is just over 20W.

Charging a phone at 5V 2A is better than nothing.

It can be charged or powered directly using a QC or PD charger. Testing with a Xiaomi 65W GaN head shows it can produce significant power, and the charger head also warms up. If needed, later on, a Type-C to banana plug adapter can be made, allowing it to use a standard adjustable power supply cable to complete the setup.