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
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 10A inline power meter based on an inexpensive module from eBay
This article documents the build of a DIY thermostat based on an inexpensive ($12) Chinese temperature controller.
The controller used is a 220VAC MH1230A.
Above is an internal view of the controller. Importantly it has a relay rated at 240V 30A, and 15A at PF=0.4. The datasheet rates the relay for a 2HP (1.5kW) motor. It uses a ‘conventional’ power supply, the brown component is the power transformer. Most similar products use inadequate relays and have low grade switched mode power supplies that create RF noise. Continue reading A DIY thermostat based on the MS1230A controller
Press “set” button for 3s get into the procedure menu code mode, display the code “HC”. Press up or down for cyclical selection of parameter code of “HC-CP-LA-HA-PU-CA”.
To enter a code, press the “Set” button, press the up button or the down button to change to the desired data and press “Set” to save and exit;
Control the temperature set: press “Set” button, display blink and it is the default setting. Press up or down to change the data and save automatically. (press on up or down for 2s or more to increase the adjusting speed ) heating control: when the temperature control mode ( code is HC) was H, e.g. the setting control temperature is 28 C , slewing range of temperature is 2 C , when the environment temperature >= setting temperature (28’C), the relay will switch off and stop the output load; when the environment temperature <=setting temperature (28C ) – slewing range of temperature (2 C ) and set “delayed start” before, the reply will switch on and output load again, (if the delayed start function doesn’t need, set the delayed start (code PU) to 0)
refrigeration control: when the temperature control mode (code is HC) was C, e.g. the setting control temperature is 28’C, slewing range of temperature is 2 C, when the environment temperature <=after setting “delayed start” time, the relay will switch on and sart output load.(suggest “delayed start” time to the default setting time to protecting the compressor, please set the (code PU) to) if it doesn’t need). Continue reading MH1210A, MH1230A operating instructions