This project was designed ad-hoc as a learning exercise for a friend who ‘needed’ to acquaint himself with Arduino.
What better than a practical exercise that demonstrates some key advantages and disadvantages of the Arduino environment.
The project was a simple digital thermometer to display normal environment air temperature, say from -20° to 50° using common and inexpensive Arduino hardware with firmware developed on the free Arduino IDE, all using hardware that was on hand. Continue reading Arduino thermistor thermometer – a tutorial
A range of inexpensive serial to Hitachi style LCD interfaces are becoming available.
This article describes the settings for one sold by eshoppingcity1 (and others) on eBay (about A$6 for 5 inc post at the time of writing but they are getting cheaper). It uses the Philips PCF8574T I2C expander chip which is supported by the user developed Arduino LCD Library V1.2.
The Slot.it CA20Z is Ford GT40 supplied as a ‘white’ kit which requires assembly and painting work.
Above is the part assembled bodies for a CA20Z and CS23B after painting with Vallejo 73.601 grey primer surfacer and two full coats of Tamiya X-6 acrylic gloss. The inexpensive Chinese airbrush pictured has been used for a few bodies, and worked very well.
A poster sought advice of the forum experts about in service evaluation of the loss of some coax feed lines…
Has anyone tested old coax cable to see if the loss increased over time? I just tested two different coax cables at 146 Mhz with the use of a Bird Model 43 Wattmeter. Power measurements were taken at the input of each cable followed by the output. The load in both cases was a 146 Mhz Ground Plane.
The test results seem to show losses similar to new coax although Berk-Tek foam coax may have had a lower loss when new.
Measured 25 watts in and 11.7 watts out which represents a 3.3 db loss. …
Assuming that the stated measured power is in fact the indicated forward power on the Bird 43 directional wattmeter and given that the actual Zo of the line should be very close to the calibration impedance of the Bird (50+j0Ω), then the Matched Line Loss (MLL) is very close to 10*log(PfIn/PfOut)=10*log(25/11.7)=3.3db which is significantly above the expected 2.6dB for ‘ordinary’ RG-8/X and warrants re-measurement as it suggests that the cable might have degraded a little. In fact, the OP later reports 10.7W out for 25W in which is MLL of 3.7dB against spec of 2.6dB… a more convincing case for replacement! Continue reading An interesting case study – in service evaluation of coax loss
Fox flasher MkII described a LED driver for an animal deterrent using 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 #3