Cheap Qi Charger

Written by  on May 23, 2015

Wireless charging is cool. Because anything wireless is cool. Next best thing to not having to do it at all.

So, people have tried to do wireless power for over a century. Think Tesla – the man, not the car. He wanted to send electricity across distances without any wires. At the moment we’d settle for charging the phone by putting it on a special pad, and avoiding three seconds of fiddling with plugging in the cable.

The Qi standard, of which we’ll talk further later, is built into the latest Google Nexus 6. And, there is a whole bunch of cheapo pads offered on eBay, one branded TechMatte. Having invested $11, I had a pleasure of taking it apart.

The top pops open without any tools, thanks! Here comes the Coil. Tesla would be happy, initially at least. The square piece of plastic that the coil is resting on is stuck onto the back of the case with two-sided tape, which one pry off to see the interesting part of the PCB.

The main ASIC is labeled GPMQ8005A, and it comes from a Shenzhen company Generalplus Technology. A QI Compliant Wireless Power Transmitter (no surprise there). I could not find an official quote on it, but on Alibaba there was an offer for $2.80.  There are two TI (ON Semi) LM324 Quad Opamps, at $0.10 these days. Two Michrochip TC4427 MOSFETS, at $0.90, Alpha & Omega Semi AO4606 30V complementary MOSFET, say $0.20. Or maybe I got them all wrong. Will microscope them again at work.

On the back of the unit is says: Input 5V – 1.5A, Output 5V – 1A. In the context of a wireless charger, the Output labeling is wrong in so many ways.

Oh, the dang thing does not work. Have to take the phone out of the case. Finding the one spot on top of the pad where the green LED goes on is a game that grows old quickly. And, if you find it, by using an App that monitors charging you will discover that it does not charge worth a damn. Cannot even keep-up with the power consumption of the screen being on.


Written by  on January 2, 2015

NETGEAR has been selling a line of cute little Internet camera systems called VueZone for a couple of years now. Actually, NETGEAR is known for WiFi access points and small Ethernet switches and routers, and they acquired a San Diego firm Avaak to get the camera product line.

The way the setup works is that several tiny battery-operated cameras talk wirelessly to the central base station plugged into the home Internet gateway, like a cable modem. VueZone uses same 2.4GHz ISM (Industrial, Scientific and Medical) band  as does WiFi, Bluetooth, and some cordless phones. A proprietary signaling scheme is likely used, to optimize power consumption of sending video frames to the base station.

AssemblyThe electronics come in a tight package, with a camera assembly connected via a flex cable to the PCB, as does the small motion detection circuit. The central processor is Texas Instruments MSP430F5524, a low power 25MHz 16-bit processor with 64K Flash and 6K SRAM, $5.50.

PCBWireless connectivity is provided via Nordic Semiconductor nRF24L01, a low power 2.4GHz RF transceiver, $2.20. There is also Cypress CY62138CV30LL 2Mbit SRAM, $3, and Xilinx XC2C32A, $1.60. Component selection of the camera assembly and the motion detection circuit warrant a second look.

BatteriesThe mechanical design is neat, though it looks like a puzzle when one tries to put the thing back together.  In the end, the pieces did fit, and were all accounted for. The sliding power switch and the battery door lock are somewhat of a kludge, though they do mostly work. The magnetic mounting semi-sphere is brilliant and gimmicky. Pretty cool, in the end.

One design choice was to use two 3V “Lithium” batteries, in parallel, whether because of discharge characteristics or physical dimensions, Shorter but fatter than AA, these batteries are known as 123 and built with the LiMnO2 chemistry. Rated at 1500mAh, they are used in cameras and medical equipment, but despite the word lithium in the title, they are not rechargeable. And 123 batteries are not cheap, with the Energizer EL123 at least $1.50 in bulk. A comparable quality alkaline AA Energizer E91 is $0.50 each in bulk.

BasestationThe base station has several lights and a button used to put the unit in the state to ‘pair’ with the camera. Not surprisingly, the base station runs off a wallwart and connects to the main Internet router via Ethernet. I would like to see what processor was picked for the job of encapsulating the video stream, before sending it to the server. But, I could not pop the case open and punted in the end. If anyone cares, let me know and I’ll take a saw to it.

Netgear recently revamped their VueZone offering, eliminating the four camera setup and raising prices on other configurations. This is perhaps in preparation for switching over to a brand new and incompatible system, an HD camera set named Arlo and priced at $350 for a two camera configuration. Fortunately, there is a brisk trade in VueZone combos and individual pieces, used or nearly new, on eBay. I picked-up the two camera setup for $75, in brand new condition. A bargain one can enjoy with a cup of gourmet coffee.