My first instructable. Maybe not rocket science but, being certainly something practical I thought I'd share.
This is just a documented summary of what I did/I've done to bring to life two nicely operative USB chargers from 5V power supplies.
Before anything, please note that the multi-ID unit was assembled way before this write-up, therefore not all its photographs are from the same time frame.
Step 1: Multi-ID USB Charger.
- An A018S3A2 PCB 5V/2'5A power supply from an old Asus WL-500GP router (I found out that I had removed its optocoupler from the board God knows why and when; after finding the little chip, I reattached it… with goddamned lead-free solder. Gosh! Fuck RoHS!). I also installed an additional heatsink and quality thermal paste on the main IC (can be seen in the photos, of course).
- A standard power cord removed from an old analog TV antenna amplifier.
- A small, transparentish cover plastic slide box.
- A female PCB mount “type A” USB connector from a generic overrated chinese charger which blew out.
- Two vintage 100KΩ potentiometers.
- A red and a green led from the past millenium, and a way more modern 10mm superbright white one.
- An old 10% tolerance 56Ω resistor, and a 165Ω precision one I scavenged from an analog multimeter many years ago.
- A DPDT japanese switch for which I'd have to set up around 30 candles over the birthday cake, if not more!
- Some wires, eutectic solder, hot glue, rotary multitool, etc.
With a multitool I made a hole on one side of the box, for the power cord. On the cover I pierced a couple holes for the leds on the same side as the cord entry; at the other side, an oval shaped hole on the top, behind the bored through window for the USB connector. Oh! Of course, I also bored a decent hole for the switch.
The 10mm white led was carefully installed on the board and ballasted with the 165Ω resistor. The board output feeds pins 1 (+5V) and 4 (ground) on the USB female. Data pins (2 & 3) go to the switch input terminals. One set of output terminals is bridged (DCP identification); each one of the other output's pins is connected to the central pin of a potentiometer. Green led/red led/56Ω resistor form a serial assembly connected to +5V. Therefore, at the green led cathode/red led anode around 3V of potential are found, which are used to feed “A” input pins on the potentiometers; needless to say, “B” pins are grounded. With such a configuration, you can freely set any voltage between 0 and 3V on the data pins by turning the potentiometers, thereby allowing many possible device IDs.
The PCB was hot-glued to the box's bottom. Attaching the USB female to the cover turned out a bit trickier than I thought initially. I was planning to make a hot glue shell for it, but for that reason I first had to wrap the metallic connector around a layer of the aforementioned hot glue and let it solidify, because seating the connector's position above a bed of liquid glue results in the glue getting inside of it, which for obvious reasons you don't want. Aditionally, the oval shaped hole mentioned in “box work” is something added at a later date in a “product revision”: hot glue isn't very sticky and the box's inner walls are very slippery; the glue shell came off the plastic cover after a few USB cable insertions. The hole allows a pillar of glue “through the roof” becoming part of the structure and allowing it to become “foundationally” seated.
Originally, just a couple of turns of adhesive tape were used to keep the box closed. At a later date, however… well, you can see it in the picture, before trimming of course.
Step 2: Multi-connector MicroUSB DCP Charger/USB Hub Supply.
Not much to say here. I had a 15 years old 2A switching supply from a BenQ camera lying around with no other possible duty than serving as my USB hub power source (i.e. almost zero usage, yet some).
I decided to add a DCP coded microUSB connector to it, without losing its ferrite bead embedded 3'5mm power plug one, over its wonderful 6 feet 18AWG output cord.
A ferrite bead can be an annoyance hanging off your phone whilst you use it; therefore, I decided to strip some spare computer fan 3 pin adapters/extenders and use their sockets to enable a plug/connector switching feature for the power supply. As the main cord has a 3-pin female socket, it can be linked to any “3-pin male to whatever plug” connector you can think of.
By the way, the stripped wire coming out of this PSU brick is actually the +5V line, an oddity for which I had to rewire/resolder a new female connector. Fortunately, I checked the supply's output polarity before arranging it all.
Plastic female connector jackets “I had met during childhood” were used to cover the stripped and soldered wire splices in a bath of hot glue. (-:
P.S.: the fan's photo… that led bastard was able to “cold start” from 5'16V, amazing!