Tag Archives: maker

1977 digital clock kit retrospective 

I recently came across a small electronic treasure from my youth. It is a digital clock kit, circa 1977. This was the first electronics kit I ever bought and built. It might have been bought from Dick Smith Electronics although there is no DSE branding — that may have come later.  I think it cost in the order of $25. I remember it being pricey enough that I had to put a few dollars aside for a while until I had enough.

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Homebrew 40m SSB rig gets CW, keyer, break-in, AGC and metering

A couple of ‘solder sessions’ finished all the wiring, debugging and testing required to deploy my Arduino Nano keyer and SWR/power meter, and the LED LDR AGC and S-meter modules into my homebrew 40 meter SSB rig (MST Mk1 from OzQrp).  Before reassembly I sprayed the front and rear panels, and added my preferred DecaDry white lettering and a protective coat of  clear satin sealer. It’s now resplendent with all the expected features of a SSB/CW monoband portable rig.

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On repair

My mower broke last time I used it. Payback for all the times I have mistreated it, yanked its handle, tilted it on 2 wheels over a gutter, or banged it roughly into a tree stump. The chassis rusted out where the handle attaches, so much so that the handle on the left side pulled off, taking with it a nicely rectangular chunk of rusted mower.  So I did what any self respecting man would do. I left it in the shed and ignored it.

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Saving an Arduino-controlled DDS VFO frequency over a power cycle

Following the success of My First DDS VFO, complete with Arduino script programming, I found myself interested in mimicking more of the features of the digital dials in ‘real’ rigs. Like dynamic incremental speed-tuning, where the tuning rate increases or decreases dynamically depending on how fast you spin the dial. More on this later. A more achievable feature is to have the band, mode and VFO come up on the frequency where you left it at the last power-down. This involves writing these parameters into the Arduino’s EEPROM, using the EEPROM library.

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More power to the activator (choosing a new LiFePO4 pack)

When the time came recently for a new battery, I jumped onto HobbyKing and was bewildered by the range of options, even after limiting the search to a particular current capacity, in my case 4-5AH, and 4S (4 cells). Wishing to leverage the ‘wisdom of the SOTA crowd’, and at risk of reopening the “whats the best battery for SOTA” chestnut, I posted to the yahoo SOTA_Australia group:

I’m buying another LiPo from HobbyKing. This battery will be for general purpose 5 watt txcvr use, but will also be used to power an afterburner of the W6JL type, using a pair of IRF2Z24N hexFETs, for up to 50 watts. My question is, what do I make of the discharge figure on the LiPo packs, which varies from 10c to 35c? I presume this is the rate at which the battery can supply current under load, the higher the better. A higher discharge figure might be important when powering an afterburner, which might draw current peaks of many amps on voice peaks. Prices seem to correspond with higher discharge figures, from as low as $25 (10c) up to $55 (35c) for packs around the 4AH rating.

My only current Li-XXX asset.  

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Artisan Printed Circuit Boards

I have been hand-making printed circuit boards since I was a teenager.  In the late 1970s I started with ‘proper’ PCBs, hand-drawn, hand-drilled, then painted with resist (bituminous paint) thinned with turpentine and applied with a tiny brush to form the copper traces, drilled holes on the copper side, etched in Ferric Chloride, cleaned and sprayed with a clear enamel to stop tarnish.  This was the way all circuit boards looked at that time, including commercially made ones in kits, and those inside transistor radios, digital clocks, televisions and ham radio transceivers.

Sometime in the 1980s I tried a ‘copper side up’ board, dispensing with the drilled holes, free-hand drawing on the copper side, painting and etching, then soldering the components directly to the copper pads. I’ve been making them this way ever since.

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