PllLdr is a generic microcontroller to load a PLL chip’s configuration registers using SPI. SPI is used by many PLL and DDS chips, data format and content varies from chip to chip.
This article documents checkout on an ADF9833 DDS chip.
The test was made on an inexpensive module purchased on eBay for about A$3 posted. This board has a 25MHz clock oscillator, but be aware they are sold with other frequencies as well, and is usable to about 40% of the clock frequency.
Above is the test board. It does not contain any form of output filtering, it really is bare bones. Continue reading AD9833 / PllLdr checkout
STC-1000 firmware change documented a chip and firmware update to a popular Chinese thermostat.
There has been enhanced firmware for a STC-1000 controller based on a PIC chip, but in my experience, most seem to be made with an STM8S003F3 chip. More recently, what appears to be a port of the PIC software to STM8 has been published at https://github.com/Emile666/stc1000_stm8.
The enhanced firmware is directed at home brewing for control of long running fermentation processes etc, incorporating storage for a number of multi-step programs (profiles). It is not really suited to more general applications like a fridge controller as for example it is more difficult for the common operation to set the set point.
This article describes a similar update to a later model STC-1000. Continue reading STC-1000 firmware change – STC-1000B
In the quest for drivers for some 18W LED plates, I have placed 6 orders for non dimming nominally 300mA drivers for 18-24W LED plates.
The LED drivers originally supplied with the LED plates were rated at 180mA (10.8W) and measured 150mA (9.0W)
The tests here use an 18W LED plate, wired as 18 pairs of 0.5W LEDs in series for a total voltage of around 60V and 300mA for 18W.
Most orders have not arrived after several months, it appears some Chinese sellers are not shipping even though they have said they did. One shipment contained a single bare board with no details, it wasn’t ordered and without ratings was consigned to the trash.
Above is a test of one type of LED driver rated at 300mA ±5%. It supplies 237mA which is 21% less than 300mA, hopelessly low on specification. The other four purchased were within 1% of the same current. Continue reading LED Driver measurement – #2
The D44-22P-01 is a Chinese LED plate rated at 15W and operates directly from 230VAC with an integrated driver.
It was purchased to explore the configuration of LEDs with integrated driver, and this driver looks deceptively simple.
The chips are JZ1009AE, a LED current driver. The 22 2835 LEDs are 9V LEDs for a string voltage of 200V. Continue reading LED plate analysis – D44-22P-01
This article is about an inexpensive GU10 230V 7W LED lamp.
Like so much inexpensive Chinese lamp product, it has not markings on the exterior or the lamp (eg voltage, current, power), but the product was sold as 7W and the box had that printed on it.
The lamp failed after less than 100h service, switching on and off intermittently symptomatic of a heat related problem.
Above is the dismantled lamp. Interestingly the LED driver PCB has “Q-3-5*1W” etched into the board, so presumably it is actually a driver for 5 series 1W white LEDs. So much for the claimed 7W, LED product performance claims are often a fraud, more so when the Chinese are involved. Continue reading LED lamp failure analysis – GU10 230VAC 7W
I have recently purchased or attempted purchase of several nominally 18W LED circular plates and associated 230VAC drivers.
The circular LED plates all had 36 x 5730 nominally half watt white LEDs arranged as 18 parallel pairs in series.
It is difficult to find datasheets from reputable manufacturers of 5730 LED. Cree makes 5630 which are similar size (though different footprint) and also rated at nominally 0.5W.
Above is the V/I characteristic from Cree’s J series datasheet with an approximation of the 0.5W line superimposed in red. The V/I combination for 0.5W is at the intersection of the two lines, about 162mA and 3.08V. Continue reading Chinese LED ratings – LED plate drivers
This article describes the internals and basic test of a no-name Chinese 4′ T8 LED replacement.
The lamp is a Type B DEP (double ended power) configuration, cool white, it requires rewiring of a traditional magnetic ballast fitting or e-ballast fitting. Don’t attempt this unless you have the needed competencies.
It has no rating label, no information about its configuration on the lamp, no warnings about compatibility… so very Chinese.
The lamp is rated at 18W 1750lm, claimed life is 50,000h but you should take that with a grain of salt. The lamps cost $6.40 ea in a pack of 10, including delivery. They were well packed and the pins had a small plastic protector.
Above, the powered end of the LED strip and the LED driver partially withdrawn from the hollow aluminium extrusion. Continue reading Chinese T8 LED 4′ tube teardown
Some months ago I purchased a TKDMR TD2B LED tester.
Above is the tester. It comes with a 3 month warranty, FWIW. Continue reading TKDMR TD2B LED tester review
I recently purchased two packs of 2x Osram Substitube LED replacements for a T8 36W florescent tube. The price per tube was about double that of a T8 fluorescent, and claimed life was 30,000 hours.
Note that LED life is usually an estimate of the time for 50% failure. Curiously, Osram individual LEDs have lower lifetime estimates for single LEDs, strings of LEDs will have lower lifetime, and lifetime for say 5% failures would be even lower. On the basis of experience with LED lighting, it might be optimistic to think that most of these lamps will last at least 5,000h.
In the event, three of four tubes had broken glass (yes, they use a glass tube much like the T8 fluorescent tube… though not sealed at the ends), and the other was DOA, no light output.
The LED driver is attached to pins at one end of the lamp, and covered by a label over the glass. Note that there are several incompatible schemes used in T8 fluorescent replacement LEDs, the other scheme bonds the adjacent pins at each end of the lamp and connects line and neutral to opposite ends. Osram calls this a “Type A” connection, and as the name suggests if can be fitted to an ordinary magnetic ballast luminaire PROVIDED the original starter is replaced with Osram’s “LED starter” which is actually a HRC fuse of around 1A rating.
Above is the top view of the electronics. Continue reading Osram Substitube tear down
Articles describing how to make a Return Loss Bridge are pretty common, but they don’t often spell out component values that are critical to accuracy.
Above is a schematic for discussion. It is somewhat simplified, but it is complete and will work. Continue reading Return Loss Bridge – some important details