At this step, it is a good idea to put the diode into heatshrink tube to avoid short circuit.
Next, double-check the connections and make sure that the converter’s “OUT+” pad is soldered to pin 1 of micro usb plug, and “OUT-” pad is soldered to pin 5.
You must check the output voltage before connecting this power supply to Raspberry Pi.
To do that, connect your external DC power supply to the DC jack and check the voltage at step-down converter’s output pads, it should be 5.0-5.3V:
If the output voltage is different, you need to adjust it by rotating the trimmer potentiometer:
Safe voltage range is 5.0-5.3V.
For the best results, gold plated Micro USB plug is recommended!
DC power supply should be greater than 6V, because step-down converter’s output voltage is always lower than input voltage.
Using 9-12V DC power supply is optimal. The amperes rating could be then lower than 3A. Higher the input voltage, less amperes are required - that’s the way step-down converter works
So, I use universal 12V 1A DC power supply with no problem.
This is a very clear description. I built a very similar circuit into my Zynthian & it’s been working fine. I did notice a couple of things when building mine…
Make sure that your ‘wall wart’ power supply has a DC output. I’ve got a whole box of assorted power supplies from various gadgets & tested them all with a scope & voltmeter. Many of them have unregulated outputs with huge ripple. So look carefully at the rating label!
There are a couple of common sizes for cylindrical DC power connectors (2.1 & 2.5 mm). The socket that you mount on your Zynthian has to match the cable.