A correspondent asked about the effect of folding back the ends of a wire dipole.
Above, a diagram of the scenario discussed in this article. The dipole of length L1 has its ends turned back by a length of L2.
Continue reading Folding back the ends of a wire dipole
This is a review of an inexpensive 8010F Chinese bang-bang thermostat that was purchased on eBay for around A$13 complete with thermistor sensor and postage.
Above is the front view of the thermostat. There are many thermostats on the market with similar front panels, but they differ in internals and most importantly, performance and quality.
Above, the rating label is clear and informational. Continue reading Review of inexpensive Chinese thermostat – 8010F #2
The STC15Fx chips use a simple TTL/CMOS async programming interface that is suited to the common USB-RS232(TTL) adapters, some of which are less than A$2 on eBay (CH341 chip).
Above, the completed adapter. Both DIP-8 and DIP-28 are located furthese from the operating lever, and pin 1 towards the operating lever, the same jumper connections are used for both chip sizes for STC15F104E and STC15F204E.
There are two spare Gnd pins next to the black jumper above but hidden from view. They are for grounding jumpers that may be required to enable programming of some ‘bootloader protected’ chips.
The 6 pin male and female headers at lower left accept a USB-RS232 adapter (break out board style or cable) with the common Arduino pinout. The only thing that commits the pinout is the 1µF bypass capacitor between Vcc and Gnd pins and the spare Gnd pins. The USB-RS232 adapter powers the chip being programmed, and it needs to be a 5V adapter.
Alternatively one of the little MAX232 adapter boards could be used with a physical RS232 port, but power will be required.
Flashing LED driver using an ESC described a LED driver for an animal deterrent using a repurposed brushless DC motor electronic speed controller.
This article describes a simpler implementation based on a Chinese 8051 architecture microcontroller, the STC15F104E.
Above, the schematic. A very simple circuit with just a handful of electronic components (one capacitor, two resistors, one LDR, one Polyswitch, 4 x LEDs and the MCU). Continue reading Fox flasher MkII
This is a review of an inexpensive MH-1210 Chinese bang-bang thermostat that was purchased on eBay for around A$13 complete with thermistor sensor and postage.
This one was a replacement for one incorrectly sent (wrong supply voltage).
Above is the thermostat. Continue reading Review of inexpensive Chinese thermostat – MH-1210 #2
A correspondent wrote seeking explanation of difficulty he was having measuring line loss using the advice given in the AIM manual using a scan with either O/C or S/C termination:
Note the one-way cable loss is numerically equal to one-half of the return loss. The return loss is the loss that the signal experiences in two passes, down and back along the open cable.
Because my correspondent was using one of the versions of AIM that I know to be unreliable, I have repeated the measurements on a cable at hand using AIM_900B to demonstrate the situation.
The test cable I have used is 10m of RG58C/U which I expect should have matched line loss (MLL) of 0.26dB, but I expect this to be a little worse as it is a budget grade cable that I have measured worse in the past. Continue reading Using the AIM to measure matched line loss
I wanted to embed some thermistors in battery packs to use them with CBAIV and sought specifications from Westmountain Radio who declined to supply the information.
It is a straight forward matter to measure the resistance of a thermistor immersed in a stable bath of water, and similarly to observe the software response to standard resistors. Continue reading Thermistor for CBAIV
This article is a review of the Baofeng GT-3TP MkIII, a hand held 2m/70cm FM transceiver.
The radio is supplied with a bunch of useful accessories (even if the power supply lacks the necessary Australian approval) and a brief and inadequate manual.
Above, the Baofeng GT-3TP purchased for about A$85 delivered overnight from Sydney. Continue reading Baofeng GT-3TP MkIII review
Correspondents have asked about application of the technique used in Antenna span spring tensioner using Antenna wire catenary calculator to a span tensioned with a counterweighted halyard.
The scenarios bear a lot of similarity, the main difference being that the tension from the counterweight is constant up to the point that the counterweight travel reaches its limit.
The tension applied is the weight force of the counterweight with a little increase to allow for friction in the sheave block.
So, lets say the scenario is a 42m wire plus halyard that adds 1m to the span under no wind conditions and can pay out a further 1m at which it reaches its limit. Lets say the counterweight is 5kg weight so 49.0N tension. Continue reading Antenna span tensioner using a counterweighted halyard
After almost 50 years working with 8bit microcomputers and microcontrollers, I thought it about time to get my hands dirty on some 32bit microcontrollers.
The plan is to investigate two streams, one ST Microcontoller based and one ATMEL based, both ARM architecture. Continue reading Time to get some experience with 32bit microcontrollers