Category: Electrical

A DIY thermostat based on the MS1230A controller

This article documents the build of a DIY thermostat based on an inexpensive ($12) Chinese temperature controller.

Controller module

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

Last update: 27th February, 2021, 11:43 AM

MH1210A, MH1230A operating instructions

Operation instructions

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

Last update: 24th February, 2021, 3:40 PM

Photo Voltaic Array – unbelievable efficiency from Chinese sellers

A friend recently purchased one of the many PV arrays advertised on eBay only to be disappointed.

A common metric used to evaluate cell technologies is conversion efficiency with 1000W/m^2 insolation. Most popular products are monocrystalline silicon technology which achieves 18-25% efficiency on an assumed 1000W/m^2 insolation.

If we look carefully at the above panel advertised as 200W, the active PV area is less than the frame size, probably \(A=0.93 \cdot 0.63=0.59 m^2\). We can calculate efficiency \(\eta=\frac{p_{out}}{1000 A}=\frac{200}{1000 \cdot 0.59}=34\%\), nearly double expected efficiency for monocrystalline cells. Continue reading Photo Voltaic Array – unbelievable efficiency from Chinese sellers

Last update: 14th October, 2020, 2:53 PM

Oyster conversion – #2 – 24W

Conversion of oyster luminaire to LED discussed a first conversion effort. This article describes a conversion of a oyster that used a T8 32W flourescent tube.

First step was to strip the magnetic ballast, power factor correction capacitor (if fitted), clips for the tube, labels that are misleading, and to check / provide the needed protective earth connection.

The LED plate used is that reviewed at LED plate analysis – 24W round plate with driver but with a new driver that delivers 260mA (though rated at 300mA).

Above is the 24W LED plate. The plate has 48 0.5W 5730 LEDs in a 24×2 configuration. If we allow that the 24W rating is total input power, driver loss is typically around 2W so the LEDs themselves will draw 22W. We expect that the voltage at 22W will be around 80-85V, and will require ~275mA current. The original LED driver supplied (180mA) is not capable of that current and was discarded. A nominally 300mA LED driver was procured for about $10 for five, and they fall short, delivering 260mA but that is good enough for this implementation. Continue reading Oyster conversion – #2 – 24W

Last update: 4th July, 2020, 12:08 PM

LED plate analysis – 24W round plate with driver

This article reviews a 24W LED plate and driver commonly sold on eBay and Aliexpress for around $12.

Above is the 24W LED plate from the sellers pics. The plate has 48 0.5W 5730 LEDs in a 24×2 configuration. If we allow that the 24W rating is total input power, driver loss is typically around 2W so the LEDs themselves will draw 22W. We expect that the voltage at 22W will be around 80-85V, and will require ~275mA current. It is shown here with a 220mA LED driver or 80% of what is required for 22W. Continue reading LED plate analysis – 24W round plate with driver

Last update: 3rd July, 2020, 11:16 AM

LED Driver measurement – #2

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

Last update: 20th June, 2020, 3:54 PM

LED plate analysis – D44-22P-01

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

Last update: 4th September, 2020, 7:40 AM

LED lamp failure analysis – GU10 230VAC 7W

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

Last update: 3rd June, 2020, 6:56 PM

Chinese LED ratings – LED plate drivers

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

Last update: 28th May, 2020, 6:57 PM