2017-12-10

UB-PB228 powerbank

Small powerbank with single 18650 cell. Branded as "URBAN BEATZ".


 5V/1A input and output, 2200mAh capacity - matches markings on LiIon cell.
 Small mounting screws are covered with sticker front.


 TP4213 from Shenzhen TPOWER Semiconductor. Chinese datasheet exists - 1A max, over-temperature protection, overcharge and over-discharge protection, output over-voltage protection, output overload protection, output short-circuit protection.
Preset 4.2V / 4.35V charge voltage with accuracy of ± 1%.
When charging, LED1 flashes (1Hz?), LED1 is always on when the battery is fully charged, LED2 is always on when discharging, LED2 is flashing when discharging low.
LED2 1Hz flashing = low battery. 
 2200 mAh 18650 cell, SZN = Shenzhen?



PCB markings: EC018_v6.1 2014.6.4

I've received this in non-working condition - it was not holding any charge at all. Few sources suggested resetting CID with screwdriver and although using this cell further might be risky it worked. Cell voltage jumped to 4.09V so CID probably "exploded" during charging.

2017-12-03

$0.99 mini flashlight

Small $0.99 flashlight from ebay.
 Single LED.
 ON/OFF switch at the back. It might be weakest point of this flashlight - it clicks nicely but light gets wobbly if it is touched when powered on. Because of this rubber cap flashlight has also some problems with standing on its back.
 This works with single 18650 AA cell - I've tested it Eneloop (as I have few of them laying around anyway).
 While this flashlight is often advertised as "3W" it consumes roughly 0.2A from 1.3V Eneloop (260mW).
Emitted light is cold. I don't have point of reference but given the small flashlight size (it can be hidden completely in hand) output light stream is satisfying - it's good enough for the trip to basement or to be used as emergency light in bathroom.

As problem with the switch was getting annoying it was time to dismantle it, which turned out to be pretty straightforward, starting from rubber cap:



Switch itself does not seem to be serviceable, but I washed it for an hour in isopropyl alcohol and then I've poured drop of synthetic oil (popular FINISH LINE green bike chain lubricant) inside - so far this is working.

Another issue (after few years of sporadic use): it seems like "+" cell contact is also not reliable and it might turn off whan shaken. Some cleaning helped, I've also put piece of paper inside to make the cell bounce less, but I'm not sure if this would be permanent solution.

2017-12-02

Car USB adapter


 Car USB adapter- 12..24V DC input, 5V/1.5A output with mini USB cable.
 NEC B772P (2SB772) transistor, 34063 switching regulator from ON Semiconductors.

2017-11-17

Planet FSD-803 8-port switch



 DC-DC converter with 34063 and SDM9435A P-channel MOSFET.


WRT54GC v2 router

 Small, popular router with 1+4 ethernet ports and WiFi.


 Whole thing is held together by plastic latches and single screw under one of the rubber feet.


 Marvell 88E6060 switch chip.
29LV800 - 8Mbit Flash memory.
EM638165 - 8Mbit SDRAM.




2017-11-16

ZTE ZXDSL 852 modem

ADSL USB modem, quite popular in Poland.

 Single screw to open.




 It is based on Unicorn II chipset from ST Microelectronics: ST70138 DMT engine and USB 1.1 controller and MTC20174 AFE (Analog Front-End: 12-bit 8.8Msamples/s DAC, 13-bit 8.8Msamples/s ADC, PGAs, filters, DCXO, PLL, line driver).
 Atmel 93C66A: 4kbit SPI EEPROM