I have a 24W LED oyster in service. The luminaire was purchased complete on eBay for about $45.
It regularly fails, usually the LED driver fails, usually due to failure of the output filter capacitor. Continue reading LED plate driver failure – 24W round plate
We have around 25 MR16 LED lamps, half of which are almost never used, the other half probably average 4 hours per day, or ~1500 hours per annum.
Remember that greens touted this ‘green technology’ to have a life of 100,000 hours. More recently, claims have been moderated to 10,000 to 25,000 hours… but that is a single LED element alone, not a set of them, and it does not include failures of the internal and external drivers. IOW it continues the fraud of green lighting.
Above, the MR16 50mm LED lamp. Continue reading Ongoing MR16 LED failures & purchasing frustrations
This article documents a second failure of a 24W LED oyster. The luminaire was purchased complete on eBay for about $45.
After about two years use, the light became sensitive to switching transients on the mains, visibly blinking when other appliances were turn off or on. After some time, this progressed to oscillating on and off for a few seconds on a cold startup, but on hot startup it was stable.
These are exactly the same symptoms as the first failure… no surprises, it is the same driver board that had a faulty capacitor replaced… and worked fine for a couple of years.
Above is the failed driver board with the replaced 105° 6.8µF input filter capacitor (at the right). The capacitor should have an ESR around 5Ω, but now cannot be measured by my ESR meters (both upper limit ~100Ω). The other capacitor also has excessive ESR. Continue reading LED plate driver failure #2- 24W round plate
This article documents failure of a 24W LED oyster. The luminaire was purchased complete on eBay for about $45.
After about two years use, the light became sensitive to switching transients on the mains, visibly blinking when other appliances were turn off or on. After some time, this progressed to oscillating on and off for a few seconds on a cold startup, but on hot startup it was stable. Continue reading LED plate driver failure – 24W round plate
I had need for a rechargeable 9.6V NiMHbattery to replace a worn out one.
The last was made by fabricating a pack with AA long life cells and it worked well for 10 years… but its time had come.
The above pack on eBay for $12 ($17/Ah) looked interesting, though it would need a wrap of heavier heatshrink. Continue reading Chinese 9.6V 700mAh Tamiya style battery pack
I had need for a rechargeable CR2 battery. The ‘standard’ CR2 is a non-rechargeable Lithium battery of nominal 3.0V.
I purchased two Ultrafire batteries advertised on eBay as Lithium-ion of 800mAh for $20. Without further qualification, we normally take Lithium Ion to be nominally 3.6V. The batteries are marked Li-ion 3.0V. Continue reading Chinese 3.0V 16340 CR2 Lithium Ion batteries
Buying Chinese batteries is a minefield. Experience has been that they rarely meet specified capacity, and less that 10% of specified capacity is not that unusual.
So, with that background I searched eBay for replacement batteries for a Makita drill / driver. The current pair of batteries are Chinese source, purchased about 5 years ago, label rating is 2.0Ah, and measured capacity now is 1.3-1.4Ah… which is not too bad, they were 1.7-1.8Ah when new (yes, below spec).
There were very many sellers selling a lot of two packs rated at 3.6Ah for around $34 including delivery. That is very cheap, too good to believe? Let’s rely on eBay Buyer Protection to put them to the test.
The two batteries arrived quickly and were put through charge / discharge cycles to condition them.
Above are the C/5 discharge curves for both batteries on the third cycle, capacity is 1.3Ah, just 36% of the label rating. Continue reading Chinese batteries – replacements for Makita 1220 battery pack
On review of the Ultrafire XML-T6 torch, I found the mode switching / mode memory so dysfunctional that it rendered the torch useless in my evaluation.
At Ultrafire XML-T6 LED torch – a fix for the dysfunctional mode memory ‘feature’ I gave a fix for that revision of the electronics, and updated it with description of a later fixed production model.
Years later, I bought two more of these due to switch failures on the originals… and guess what, the flash on power on returns.
Let’s pull them apart.
They have a new revision / version of the LED driver PCB, and it has provision for a resistor in parallel with the capacitor, but the resistor pads are not populated.
Above, the LED driver board with a 100k resistor added, it is the far component. This was an 0805 part that was on hand, but ideally should be a 0603. Continue reading Ultrafire XML-T6 LED torch – a fix for the dysfunctional mode memory ‘feature’ #2
This article describes a simple and inexpensive inline power meter for use as a test instrument.
The box cutouts were done on a CNC router, but they could be done with hand tools.
Above, calcs of feeds and speeds for the CNC router. The box is actually ABS, but cutting speed for Polycarbonate is the same.
Above is the tool path for one side of the box. The cutouts suit the 7P-2 strain reliefs. The gcode is generated from a custom Python file using a custom library of common shapes that I use. Continue reading A handy 230VAC 15A inline power meter based on an inexpensive module from eBay
The RK2672AM is a Chinese high voltage test set. This article describes a process for calibration of the device.
This process should not be attempted unless you have the requisite competencies, experience, tools and test equipment. There are dangerous voltages involved, so assess the hazards, plan your work, don’t attempt it if fatigued or alcohol enhanced.
Above is the front panel of the RK2672AM. Continue reading RK2672AM – calibration