{"id":5712,"date":"2009-03-04T05:20:00","date_gmt":"2009-03-03T18:20:00","guid":{"rendered":"https:\/\/www.homebrewradio.us\/blog\/2009\/03\/04\/et-phone-home-with-minimalist-qrss\/"},"modified":"2025-07-21T19:29:37","modified_gmt":"2025-07-21T09:29:37","slug":"et-phone-home-with-minimalist-qrss","status":"publish","type":"post","link":"https:\/\/www.homebrewradio.us\/blog\/2009\/03\/04\/et-phone-home-with-minimalist-qrss\/","title":{"rendered":"ET Phone Home! With Minimalist QRSS!"},"content":{"rendered":"

\"\"<\/a>I knew that Alan Yates, VK2ZAY, was just the man for this project. Alan and I met up several years ago when Billy and I spotted and built his Trivial Electric Motor (we still have it, and occasionally fire it up to amaze visitors). On SolderSmoke 102 I mentioned the possibility of a one transistor QRSS transmit station. Obviously this would require some sort of mechanical keyer. I thought of a clock drive. Alan pointed out the in the 1982 Steven Spielberg movie, ET had used a saw blade as his mechanical modulator (see above). Alan also had some intriguing ideas of his own:<\/p>\n

G’day Bill,<\/span>
Thanks again for noticing my QRSS signal making it through to <\/span>Europe<\/span>.<\/span>

Your talk about mechanical solutions for QRSS modulators immediately<\/span>
made me recall “<\/span>E.T. the Extra-Terrestrial<\/span>“. The “Phone Home” device he<\/span>
built had a modulator based on a sawblade IIRC – its been years since I<\/span>
watched that 1982 classic.<\/span><\/p>\n

One easy hack might be to use an <\/span>AC synchronous motor<\/span> out of a gobo<\/span>
rotator (for example, I got one out of a <\/span>fibre optic christmas tree<\/span> that<\/span>
expired from overheating). Its <\/span>reduction drive results<\/span> in a fairly slow<\/span>
rotation which might drive a modulator plate. You could do the pickup<\/span>
optically using a LED\/photodiode (or transistor, or even an LDR I guess)<\/span>
transmission pair. Electrical contacts would work too, but doing it<\/span>
optically probably means it would have a longer life.<\/span><\/p>\n

A tape loop system might also be practical and would allow long<\/span>
modulations to be encoded at reasonable tape rates. A syncro-drive gobo<\/span>
has to be turned fairly slowly and pushes the “density” of the data<\/span>
fairly high so the mechanical or optical sensor gets harder to just<\/span>
throw together. I am sure a clockwork driven disk could be made to<\/span>
work, it just might have to be fairly large.<\/span><\/p>\n

Mechanical readout might be a microswitch and holes in the plate, or<\/span>
even using PCB material with the pattern on it (etched or masked), and a<\/span>
brush contact. To minimise wear a brass small roller held against disk<\/span>
with spring tension would work. Oxidation on aging might become a<\/span>
problem – yeah the more I think about it I am liking optical better.<\/span><\/p>\n

You can also do it electrically using a diode matrix which can be read<\/span>
out with some counters. Of course that defeats the original purpose<\/span>
which was to make a single transistor QRSS beacon with a mechanical<\/span>
modulator.<\/span><\/p>\n

One completely insane idea that just occurred to me is to build a slow<\/span>
mechanical oscillator (say driven by a <\/span>Stirling Engine<\/span> or a Curie Point<\/span>
Pendulum heated by a small candle) and modulate the RF oscillator with<\/span>
that. The mechanics or thermal system might directly effect the RF<\/span>
oscillator frequency. Who will make the first candle-powered QRSS<\/span>
beacon with thermopile PSU? \ud83d\ude42<\/span><\/p>\n

Regards,<\/span>
Alan<\/span>
http:\/\/www.vk2zay.net\/<\/span><\/a><\/p>\n","protected":false},"excerpt":{"rendered":"

I knew that Alan Yates, VK2ZAY, was just the man for this project. Alan and I met up several years ago when Billy and I spotted and built his Trivial Electric Motor (we still have it, and occasionally fire it up to amaze visitors). On SolderSmoke 102 I mentioned the possibility of a one transistor … Continue reading “ET Phone Home! With Minimalist QRSS!”<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[165],"tags":[],"class_list":["post-5712","post","type-post","status-publish","format-standard","hentry","category-qrss"],"_links":{"self":[{"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/posts\/5712","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/comments?post=5712"}],"version-history":[{"count":1,"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/posts\/5712\/revisions"}],"predecessor-version":[{"id":5714,"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/posts\/5712\/revisions\/5714"}],"wp:attachment":[{"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/media?parent=5712"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/categories?post=5712"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.homebrewradio.us\/blog\/wp-json\/wp\/v2\/tags?post=5712"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}