Review on 🔌 Qunqi 5pack MP1584EN Ultra Small DC-DC Step-Down Adjustable Module Buck Converter - 3A Power Supply for Arduino, Supports 24V to 12V, 9V, 5V, and 3V by Fernando Ramani

5 transducers came in individual electrostatic envelopes in a tiny cardboard box, very nice packaging for such a low price. The input and output pads have through holes with a metal coating that allows soldering with good strain relief. As noted by other reviews, the adjustment potentiometer is tiny, but I was able to adjust the 12v input to 9.05v in less than a minute while trying to get 9v. Based on other reviews, I was very cautious with the potentiometer. , with a 1.5 mm Wiha slotted screwdriver. Although the pot may appear to require a #1 Phillips screwdriver, a smaller flathead screwdriver may be better for fine adjustment. You also need to know the position of the slider to make sure you don't turn it all the way. One of the slots is slightly shorter, indicating a slider. The switching frequency appears to depend on the load current drawn. The ripple with a 2200 ohm resistor at 9V (4mA) was a 20kHz triangular wave with a 40mV peak-to-peak ripple. The 20 ohm (450mA) load had a higher signal frequency and slightly less peak-to-peak noise. I'm not sure of the exact frequency, but it was slightly higher than 4mA. Both waveforms were mostly ground waves with little high frequency noise. I tried the 9V output with a recently purchased handheld oscilloscope. There were noise issues when using the 9V wall adapter I bought for it, but it worked great with that power supply. Output current 900mA. The output voltage was 9.00 V at a switching frequency of approx. 900 kHz and a residual ripple of 40 mV. Warming was not felt. Given the limited current draw of the one converter I tested, this looks like a very good product that I will use again and again. The price is also quite reasonable considering the quality. However, as noted in other reviews, some care is required with the adjustment potentiometer.