Some while ago I purchased a EZP2013 device programmer on eBay.
There were literally scores of sellers, and they all looked the same, and some variation in price from about US$25 to US$50… which is not unusual.
I used the thing a few times, and it was clearly a very poor product so I replaced it with a SOFI SP-8B which cost close to US$50 on Aliexpress including a bunch of (6) adapters. Continue reading Chinese counterfeiters at it again – EZP2013
Seeing the promotion of a clear adhesive with cure initiated by ~400nm UV light from a LED source, one’s mind wondered to its application for attaching temperature sensors to heatsinks etc.
A sample of Kafuter K-300 was tested.
Above is the test jig, a 1N4004 diode is attached to the corner of a scrap of 1.6mm thick aluminium sheet using the adhesive which was cured with UV light and then allowed 10 hours further to strengthen (if that helps). Continue reading UV cure adhesive for temperature sensors
This article documents an implementation of PAROT (Power Amplifier Run On Timer) using Transformerless power supply for PAROT.
This PAROT uses a 230V AC relay for 230V mains switching and includes PTT switching using an FOD852 opto coupler.
The intended application is to control power to a valve PA, providing programmable heater delay, and cool down delay of power off.
Above is the electronics built on a small piece of Veroboard. This one uses a 0.47µF cap as the power supply current requirements are a little lower than for the SSR. Continue reading PAROT with transformerless power supply and 230V AC relay
This posts shows a measurement of ambient noise and comparison with the data given at Expected ambient noise and its more detailed references.
The test scenario is my 40m station, a G5RV inverted V dipole with tuned feeders, a balun and ATR-30 ATU. Antenna system losses are less than 1dB.
The chart above gives a range for expected ambient noise at 40m.
Above is a screen shot from a spectrum analyser measuring power in 1kHz bandwidth from 7.0 to 7.1MHz. The band is mostly unoccupied, and the mean noise power is about -99dBm, it would be 3dB higher in 2KHz bandwidth (ie -96dBm). Continue reading Expected ambient noise – in practice
One of the casualties of the cessation of VK1OD.net was an article on expected ambient noise.
The original work was based on ITU-R P.372-8 which has been updated to -10, -12 and now -13, but the updates do not alter the basis for the original article.
Since the work was a reference cited on my FSM pages, it has been updated and copied to Expected ambient noise level. The graphics and tables in the article and the PDF file all refer to ITU-R P.372-8 but remain correct wrt ITU-R P.372-13 (2016).
This article documents an implementation of PAROT (Power Amplifier Run On Timer) using Transformerless power supply for PAROT.
This PAROT uses a 10A SSR for 230V mains switching and does not include PTT switching, but space exists for a FOD852 opto coupler for PTT switching.
The immediate application is to control my main station power supply so that if it has been in use, is hot and fans are running, the PAROT provides in this instance a 5min cool down before powering down.
Above is the electronics built on a small piece of Veroboard.
Above is the copper side of the Veroboard. The layout is designed to accomodate another implementation using a small Triac to switch a 230V AC relay. The board has been given a heavy coat of acrylic PCB lacquer to improve voltage withstand.
The PAROT is assembled inside a small die cast aluminium box with stick-on rubber feet.
Above is a view of the interior of the box. A 430V MOV is connected across the SSR output terminals, it is not clear whether the device has internal protection (Chinese product, very brief data). The LED / momentary switch on the right is the only control and indicator for PAROT operation. Note that because of the transformerless power supply, everything inside the box is potentially at mains voltage… a fact that must be kept in mind when working on it. An isolation transformer is a worthwhile tool for working on these type of things. Continue reading PAROT with transformerless power supply and 10A SSR
I use a number of implementations of the DS1307 or DS3231 Real Time Clock chip, preferably the latter these days as they are considerably more accurate and compatible with DS1307 code.
In some applications, it is necessary or sometimes just better to preset the clock before connecting it into the application, and the need arises to set the clock ‘stand alone’. The method I have used for this has been clumsy and not as accurate as one might want for the DS3231, so this article describes a new solution.
The solution uses an Arduino as the engine if you like. Above is an Arduino Pro, but a range of similar Arduinos would be equally suitable. ALso pictured are three RTCs, one connected to pins A2, A3, A4 and A5 providing GND, VCC, SDA and CLK respectively. Continue reading Arduino app to set DS1307 Real Time Clocks
Power Amplifier Run On Timer (PAROT) (Duffy 2013) reported some measurements of the voltage withstand of Veroboard. Voltage withstand between tracks was observed to be just over 1400Vpk.
This article reports some further measurements of genuine Vero strip board.
Above is the test piece. Continue reading Voltage withstand of Vero strip board
This article documents design of a capacitive transformerless power supply for operating low voltage, low power logic from power mains. The intended application is PAROT (Duffy 2013), though it has potentially wider application.
(Microchip 2004) gives a method for design of a capacitive transformerless power supply for operating low voltage, low power logic from power mains. The equations seem simplistic for a circuit whose apparent simplicity belies the complexity of an optimal design that properly tolerates supply voltage and load variations. For that reason, a SPICE simulation was used to refine a design.
The immediate application is for the PAROT chip driving a 40A SSR.
Above is measured characteristic of a Fotek 40A SSR, it seems typical of several similar types on hand. It appears that much smaller SSRs in the 2A range require fairly similar current. Continue reading Transformerless power supply for PAROT
Fox flasher MkII – owenduffy.net described an animal deterrent based on an STC 8051 microcontroller and running from a single LiPo cell.
This article describes a further development using a solar cell, shunt regulator, 1S LiPo cell with protection board, and two high power red LEDs.
Above, the unit constructed in a medium size Jiffy box, and a 6V 0.6W PV panel fixed to the top with silicone adhesive. The LDR is fixed to one end with silicone adhesive.
Two SM 1W red LEDs are fitted to opposite sides. They are 120° LEDs, the holes are countersunk to provide for light dispersion and the LEDs clamped to the inside with small brass brackets and heat sink rubber, a little silicone adhesive seals the holes. Continue reading Fox flasher MkII – high power 2 LED solar powered beacon