Small untuned loop for receiving – simple model with transformer gave a simple model for analysing a loop and and Towards understanding the YouLoop-2T at MF/lowHF applied that to the YouLoop-2T.
Above is the Airspy Youloup-2T. Try to put the two turns thing out of your mind, it is misleading, panders to some common misunderstanding, and so does not help understanding.
It would seem that many are quite confused by information from Airspy. The following quote from an online forum captures the confusion. Continue reading YouLoop-2T and the self resonance bogey at MF/lowHF
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
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
This article proposes an explanation of how the balun used on some Tonna Yagis works.
It appears Tonna no longer manufactures these antennas, I do not know if this design is novel. I do not recall seeing them used by other manufacturers, they may be protected by patent.
Above is a pic of the balun structure on a 2m antenna.
Above, the manual shows that the black sleeve on the balun sleeve would be slid up over the coax connector, making a neat finish. There are slightly different versions for 70cm antennas. Continue reading (How) does this balun work? (Tonna / F9FT balun for Yagis)
I purchased some R7s LED replacements advertised as 30W and 40W.
Above, what arrived after almost three months was four of the above, unmarked (nothing on the box or on the lamp). Continue reading Chinese R7s LED replacement – review
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
This article documents a station for propagation observations on 144MHz, in this case the antenna system part of the entire system.
Above, the antenna is a 4 element Yagi with Gamma match. Continue reading 144MHz propagation experiment – antenna
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