IoT – exploration of LoRaWAN – part 4

My experiments with LoRaWAN were cut short by the announcement that The Things Network (TTN) was to discontinue its V2 network in favour of a new V3. This coincided with Laird’s decision to manufacture region specific versions of its gateway, and all existing equipment was designated US region and would not directly support frequency plans used here in Australia.

After some years there is a solution. Newer firmware for the RG191 supports the more generic Semtech basic forwarder and protocols for TTN to configure the RG191 frequency plan… so it is possible to connect the RG191 to the North American server (instead of the AU server), and configure the gateway in TTN for Australian frequency plans, and it all comes together. Continue reading IoT – exploration of LoRaWAN – part 4

Garden environmental telemetry project – part 1

This is the first in a series of articles describing a simple maker / DIY IoT garden environmental telemetry system. The project is a derivative of IoT water tank telemetry project – part 1, and some of the optional components are as per that project (eg battery / solar power).

The measurements of this (get) and an another project (bme280r) are posted to the same Thingspeak channel (https://thingspeak.com/channels/436449 at this time).

Above is a screenshot of the Thingspeak channel. Continue reading Garden environmental telemetry project – part 1

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

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

Setting a torque wrench when using an offset adapter

Sometimes an offset adapter is necessary or convenient on a torque wrench. This calculator calculates the correct torque wrench settings to achieve the desired fastener torque.

The torque wrench is designed to provide a torque indication based on a force applied to the handle and the length about which that force acts to turn a fastener. The calibration may not hold if that geometry is changed by some form of adapter.

An oft cited solution is to set the adapter up at exactly 90° to the long axis of the torque wrench, but that is not always possible or convenient.

For the purposes of this explanation, let’s use the Facom S.234 adapter (above). Continue reading Setting a torque wrench when using an offset adapter

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

Karen’s Victa

Karen purchased a Victa lawnmower many years ago, and it has expired.

Victa was Australian, but now owned by Briggs & Stratton. The engine is different to most two stroke small engines, the notable differences are:

  • Victa’s G4 plastic carburettor; and
  • the engine is built “upside down”, the flywheel is underneath (ie on the PTO end), and there is no main crankshaft bearing above the big end, the crankshaft is supported by two bearings below the big end.

This article describes the service work to get the mower into good working order.

First checks / observations

The handle bolts and handwheels don’t work, someone has replaced a cup head bolt with a screw and it does not locate in the tube, so a screwdriver is needed to tighten the handle. The lower bolts are loose and need tightening.

The mower takes a lot of effort to push, the wheels are jammed up with string and stuff binding the bearings.

The blades are beyond service life, chipped and blunt, and the blade carrier and mower base are caked with wet decaying grass clippings.

Fuel tank contaminated with solids and water.

This is an air cooled engine, and the cooling fins and cooling fan were caked with oily grass / dust residue. This leads to higher operating temperature, shorter engine life, and performance problems.

Above, the air filter is filthy and will cause rich running which results in carbon build up in the combustion chamber and blocked muffler. Continue reading Karen’s Victa

dB loss is always negative… right???

A recent online posting set out to inform the masses:

The concept of free space path loss (FSPL) is widely misunderstood. Some university lectures and even texts get it wrong. …

The result is some dB of loss which is the ratio of the power received to the power transmitted expressed in dB form.

Errr no! Continue reading dB loss is always negative… right???

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