The Modular Bench Power Supply To Rule Them All

Right now, [The Big One] is using an ATX power supply as a bench power supply for all his electronics projects. It works, but it’s not ideal. The next step up from a power supply from an old computer is, in order, one of those Chinese deals on Amazon, a used HP supply, or for the very cool people among us, building your own. [The Big One] is very, very cool and he’s building the modular bench supply to rule them all.

This is not your $100 china special power supply that [The Big One] would have to buy again in a few months. Inside this massive power supply is a massive transformer and rectifier that fans out to multiple power supply modules. The modules themselves will be based on an OPA548 that will be able to supply up to 3A with current limiting.

Each of these channels will be controlled by an ATMega32u4, with all the fancy stuff you’d expect from the ultimate supply; USB for setting voltage, current, and logging data, a nice LCD character display, and it’s surprisingly cheap; just about $100 for the transformer, and about $50 for each module.

It’s shaping up to be a great build, and with all the features, a power supply that would also make a great kit. If you have any input you’d like [The Big One] to hear, let him know on the project page.

Another take on using ‘dead’ batteries

Here’s another circuit that can be used to squeeze the remaining potential from supposedly dead batteries. Just like the AASaver, we see this as a useful prototyping tool, providing juice for a breadboard even though it’s not reliable enough for long-term use (the batteries are just about through after all).

First off, the image above shows rechargeables instead of alkalines. We don’t recommend this as the circuit has no cutoff feature and the 0.7V input for the boost converter surely is below the recommended low-voltage limit for those cells. But that aside, we like the diminutive board which solders onto the end of a battery pack. It uses an SC120SKTRT which is a variable boost regulator capable of outputting 1.8-5V depending on resistor choices. You can leave the resistors off and it will default to 3.3V, set the output explicitly, or roll in some potentiometers and use your multimeter to tune the output.

This regulator costs more than the MCP1640 used in the AASaver, but it appears to use less passive components making for a smaller footprint. At a total of $3.50 plus the PCB (which will be a snap to etch at home) this is another great option to top off your next parts order.

[Thanks Uwe]

Bench supply with current limiting

This is a bench power supply with adjustable voltage and current limiting. [Sylvain’s] creation can regulate 0-25 volts while sourcing 0-5 amps. Current limiting is a nice feature as it will allow you to test your prototypes to ensure the power regulator you choose will not be over or underpowered.

This supply is really a two-in-one. The case has two separate circuits so that you can have different power rails going at the same time. There is a microcontroller involved, but the ATmega32 doesn’t do anything more than measure the voltage and amperage and drive the graphic LCD screen. Two potentiometers are responsible for setting the voltage and limiting the current.

[Thanks Sargonout]