Category: Electronics

Digital display for DIY 25W dummy load – part 4

Digital display for DIY 25W dummy load – part 1 described a  digital display for a DIY 25W dummy load / digital wattmeter. The original research tested implementations on an Arduino Nano (ATmega328P) and Arduino Mini Zero (ATSAMD21). Though the Zero appears the better chip (32bits, better ADC resolution etc), the dev board is so noisy (ADC wise) that the Nano produces better results.

Other candidate chips are those of the newer AVR chips, and to that end some ATtiny1614 chips were purchased for trial. Unfortunately I have not seen inexpensive dev boards and the chips are not available in DIP format, these are SOIC14 (SSOP14) 150mils.

Above is the result of this morning’s cooking… three ATtiny1614 chips on DIP style break out boards for prototyping. The chips were soldered in a T962 IR reflow oven. The very long unmasked sections of pad to accommodate different width chips make for a messy looking solder job as the solder runs along the long pads. Continue reading Digital display for DIY 25W dummy load – part 4

Last update: 24th September, 2022, 6:11 AM

CG K/ J/ S/ B to 4-20mA 0-1800 Celsius Thermocouple Converter TC Input 4-20mA Output Head-mounted Temperature Transducer – first impressions

CG K/ J/ S/ B to 4-20mA 0-1800 Celsius Thermocouple Converter TC Input 4-20mA Output Head-mounted Temperature Transducer.

So the concept is that one can program the transducer module for a range of input sensors, and lower and upper limits to the conversion range. Another significant benefit is that it does cold junction compensation (and it does not seem possible to disable it if you wanted).. Continue reading CG K/ J/ S/ B to 4-20mA 0-1800 Celsius Thermocouple Converter TC Input 4-20mA Output Head-mounted Temperature Transducer – first impressions

Last update: 11th September, 2022, 11:06 AM

EARU Programmable Thermocouple K J PT100 to 4-20mA Converter TC RTD Input 4-20mA Output Head-mounted Temperature Transducer – first impressions

This article is a review of the EARU Programmable Thermocouple K J PT100 to 4-20mA Converter TC RTD Input 4-20mA Output Head-mounted Temperature Transducer.

So the concept is that one can program the transducer module for a range of input sensors, and lower and upper limits to the conversion range. Another significant benefit is that it does cold junction compensation (and it does not seem possible to disable it if you wanted). The stated cold junction compensation range is narrow at 20-60°, it seems unlikely but bears testing. Continue reading EARU Programmable Thermocouple K J PT100 to 4-20mA Converter TC RTD Input 4-20mA Output Head-mounted Temperature Transducer – first impressions

Last update: 5th September, 2022, 6:38 PM

Neewer Macro LED Ring Light Flash RF550 – Guide Number

I purchased a Neewer Macro LED Ring Light Flash online for a modest price (~$50).

It was described with specifications, but specifications for Chinese product are not to be trusted… so it deserves measurement (though shortfall would become evident in use in short time).

This article reports measurements of the flash mode characteristics. Continue reading Neewer Macro LED Ring Light Flash RF550 – Guide Number

Last update: 25th August, 2022, 9:44 AM

Digital display for DIY 25W dummy load – part 3

Digital display for DIY 25W dummy load – part 1 described a  digital display for a DIY 25W dummy load / digital wattmeter. The original research tested implementations on an Arduino Nano (ATmega328P) and Arduino Mini Zero (ATSAMD21). Though the Zero appears the better chip (32bits, better ADC resolution etc), the dev board is so noisy (ADC wise) that the Nano produces better results.

This article documents tests on three other dev board alternatives:

  • Arduino Nano Every (genuine);
  • Wemos SAMD21G board; and
  • Seeed XIAO mini Zero.

Baseline: Arduino Nano v3.0 (clone)

Above is the initial prototype Arduino Nano v3.0 (16MHz ATmega328P) with OLED display. This clone has a CP210x serial chip, clones with a claimed FTDI chip are probably fakes, ones with CH340x chips are probably ok. Continue reading Digital display for DIY 25W dummy load – part 3

Last update: 21st August, 2022, 7:36 AM

FT37-43 for a 49:1 EFHW transformer enquiry

A correspondent asked whether Sontheimer coupler – transformer issues – an alternative design – FT37-43 could be used to inform design of a 49:1 EFHW transformer based on the same core, but with a 2 or 3t primary.

In the case of the Sontheimer coupler the winding with the higher number of turns appears in shunt with the nominal 50Ω load, and its effect on InsertionVSWR and the core loss can be predicted reasonably well and confirmed by measurements as in the referenced article.

In that instance, a 7t winding in shunt with the nominal 50Ω load causes excessive core heating, a 3t winding will be worse, and 2t worse again.

The case of an EFHW transformer is somewhat similar, the difference is now that the winding with less turns in approximately in shunt with the nominal 50Ω primary referred load. The same Simsmith model can be used to predict likely InsertionVSWR due to primary magnetising admittance, and the core loss.

Let’s try the 3t case first, with the experience of the referenced article we can expect it will have insufficient turns for good performance.

Above is the Simsmith model of a Fair-rite 5943000201 core (equivalent dimensions to FT37-43) with a 3t winding. Note this does not apply to Amidon #43 as their material is significantly different in characteristic. Continue reading FT37-43 for a 49:1 EFHW transformer enquiry

Last update: 14th April, 2024, 1:34 PM

Making a jtag2updi adapter

This article is about selection and reprogramming of an adapter to make a jtag2updi adapter using the code published at https://github.com/ElTangas/jtag2updi.

The purpose is for programming some of the newer AVR chips that use UPDI.

Above is a JTAG ICE that I purchased, but I did not check the pics carefully enough and fell foul of the Chinese Cheats. The chip arrowed is the USB-RS232TTL chip, it is a PL2303HX which will not work in Windows 10 since the driver was poisoned many years ago. Continue reading Making a jtag2updi adapter

Last update: 13th August, 2022, 2:29 AM

SNTP synchronised clock v0.04 – beta release

The SNTP synchronised clock (ssc) is an ESP8266 based time of day clock with an LED display.

Above are two prototypes both using HT16K33 display modules. (The display has a blinking colon, it is off in the pic.) There is a silicon photo transistor just above the display, used to sense day/night and the firmware changes display brightness. Continue reading SNTP synchronised clock v0.04 – beta release

Last update: 17th July, 2022, 4:53 PM

Chinese 9.6V 700mAh Tamiya style battery pack

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

Last update: 28th July, 2022, 6:38 AM