DROK Micro Dual Power Supply - DC to DC Buck Boost Converter 4.8-35V to ±15V Positive Negative Dual Output, Step Up Voltage Regulator for OP-Amps

I needed a reliable and stable 5V voltage source to power an Arduino board and some small electronics on my truck. This was a cost-effective solution, taking my ~12V truck voltage and converting it to 5.0V. It's a good form factor, operates efficiently and dissipates minimal heat. I'm quite pleased with it.

To get this supply quiet enough for audio use I had to pre-load it with about 70 mA. With a 140 mA total load the input start-up current was about 2.3A for approximately 50 ms and would over-current trigger almost all 12V 2A 24W switcher's outputs despite the load being only about 4W. The 12V input current, when operating, was around 400 mA. With only the 70 mA load the peak current was about 3.3A. For reliable operation a 12V 4A switcher is required for start-up: It takes a 48W switcher to deliver 4W output despite its near 85% efficiency. A 24V input supply does not reduce the peak current - it only shortens the duration. An unregulated linear 12V wall mount supply will likely be more tolerant of the start-up current. For this reason I'm giving it 4 stars.

This is a really neat module. Performs as advertised. Operates and buck or boost over wide range, providers ground-referenced +/- 15 vdc. Remarkably low ripple at the output, better than my cheap Chinese variable supply with current limit. The controller chip labeling has been scraped off, but probing the switch pins it's clearly a flyback regulator similar to LM2587 (different pinouts) attached to a transformer. It requires a minimum load of 30 mA, and with 1/2 watt resistors they still reach 70 decrees C... BE CAREFUL! Update: I was working on an op-amp project and my cheap adjustable supply blew a capacitor, got 2 volts ripple on the output. I took this DROK module and fed it with 2x 18650 batteries and was back in business! +-15 volts from 2x18650s, love it!

While it is dual output, it is not adjustable. I am an electrical engineering student and did not know that they do not all come with adjustable knob. That’s my bad. I have not used it due to this but will keep it for future labs.

I needed +/-15V for a dual supply op amp Arduino shield. Connected this to the VIN pin on the Arduino headers and now I have the voltages. Very quick easy. But then I went to mount this board on an Arduino protoshield and found out that the headers just don't line up with the holes. Looks like they are maybe off by 0.05". You make it fit and it is fine, but it looks weirdly skewed. Hmmm.... Anyway, does work and otherwise seems great.

Final edit: Tossed it in the land fill. Noise was too much. Don't waste your money. Buy instead Eletechsup +-5V 6V 9V 10V 12V 15V 24V Positive & Negative Dual DC DC Boost-Buck Converter (with Terminal, 5). No Noise with minimal filtering. Much, much better. Tried to use it in an audio circuit to power two 741 op amps. Too noisy to be used in this application. Filtering per their included instructions made no difference. Replaced it with two 9V batteries. Update: I continued toying with it, using different combinations of components. 8 capacitors, an inductor, and 2 voltage regulators later I got the noise level down enough to be tolerable. The necessary added components makes this item not very cost effective.

I found that if the load I am powering ever drops below 30ma I'll likely want to consider the use of "two" 470 ohm 1%, 1 watt resistors (+ to Gnd and - to Gnd), to maintain the 30ma load requirement for proper performance of this power supply. Unfortunately this constant draw of 30ma on the plus and minus side of the 15v output is hard on a Battery if a Battery is the power input source. A 470 ohm resistor across 15v actually draws about 32ma. However, if the minimum load current of the device I am powering is known the value of the two resistors can be adjusted accordingly. Note that 30ma across 470 ohms is close to 1/2 watt, thus it "is not" (IMO) a good idea to use anything less then 1 watt 470 ohm resistors, safety factor. Or you could add two LEDs and their respective current limiting resistors and get something like 20ma (one across each output), then adjust your load (if needed) from there.

It seems to be a well-built unit and it worked. But, be aware that it requires numerous external components to function properly and the power output de-rates when using a 5V input. See the photo of the application notes which came with the unit.