2012-08-19

Teardown: cheap (no name) compact fluorescent lamp







Teardown: miniature voltage tester

I've bought this miniature voltage tester in 2001 for a equivalent of $1. Similar tool is now available at dealextreme for $4.30.
It has flat screwdriver head, but it is quite fragile and I believe it would broke quickly if high torque would be applied, so you will need real screwdriver anyway.
It works in a similar way to classic neon lamp voltage indicator, but instead of single finger contact it has two, one for direct measuring and one for detecting voltage without physical contact. It is not as sensitive as battery powered indicators, finding wires in the wall is rather difficult if not impossible.


 Quite easy to open: my unit was not clued.
 The trick behind this simple tester is thick film resistor circuit.

2012-08-18

Teardown: Tatarek 12V, 400mA power adapter

Classic, heavy and solid power adapter with transformer and 7812 regulator.

6VA transformer = proper power for specification. One small power supply I've used melted under full load.



Teardown: Casio TC-530 cordless phone with answering machine






 MC13109A
 Phone line adapter
Handset accu


 MC13109A again


 Two microphones directed at slightly different angles - probably noise cancellation
 Both handset and base are easy to disassemble and reassemble. Nice touch is number of screws holding particular PCB printed as silk screen layer.



Teardown: ELEKTRONIKA MK66 calculator

Vintage scientific calculator made in USSR with vacuum fluorescent display (VFD). Powered by 3xAA or external adapter.
4.5V, 0.45W
VFD up close - it's little dark in daylight (may be effect of limited VFD lifetime), but it is very impressive that this calculator is still working.
Calculator uses only single integrated circuit which is again quite impressive - this IC contains both logic circuits and high voltage VDF driver.
 VFD DC/DC converter.
 Transformer construction is quite intersting.
  Whole PCB.

2012-08-12

Teardown: solar powered garden light

Cheap (less than $1) solar powered garden lamp. As many other similar products calling it a light source is questionable - single LED inside has 17 mW, it has small light angle and it's pointed downwards, so significant amount of light is wasted. It may not like heavy rain also as it offers IP43 protection only. I was aware of it, but I bought it for its solar battery only.

Unusual 2/3 AAA 1.2V, 200 mAh NiMH cell. May be able to power LED all the night.
Specialized integrated circuit that works as a boost driver for LED that is active only when no light hits solar battery (in complete darkness).

 Solar battery parameters: open circuit voltage 2.8V, short circuit current 10 mA (close to 60 W light bulb). It's worth noting that it is made of glass - some other lamps I've seen are using cells with plastic top that tend to become mat and stopping sunlight with time (year or two outdoors).

2012-08-11

SD cards - some speed tests

All tests were made using same card reader.

Kingston 128 MB



Kingston 2 GB

Goodram 8 GB - dissapointing when comparing to manufacturer claims: 20 MB/s for both reading and writing. In test: slower than cheap 2GB Kingston except for sequential writing.
Update: it looks that measured speed is in fact similar to declared but the problem lies elsewhere - Goodram was making (for a short time?) cards named in the same way based on SLC memories that got overall good reception (positive press reviews). They were rebranded Toshiba Professional series most likely. Then Goodram started to distribute much worse MLC memories named in the same way. This is definitely unfair practice.
Update 2. This card was proven to be unreliable. It passed initial test with H2testw, but then it lost data when used in my camera. It failed to format several times giving errors. And then after successful formatting and some time it failed again proving to be worthless. Unfortunately it was bought online and trying to replace it (shipping) would be more expensive then buying a new one.
Product number from blister: SDC8GHC10PGRR9.



Kingston 8GB, micro SD, class 4.




4 GB version gives identical results.