Comments for "Larson Scanner"

25th October 2010 19:49

Alan Yates wrote...


I didn't have a piece of doughnut board long enough and couldn't find my track-breaker tool for using veroboard... If I was to make a PCB for it it would be much easier to build.

The solar cell thing is very handy, especially for testing IR remote controls. In the past I used to use an AM radio near remotes to hear their RFI, actually testing the IR output is a far better test.


Indeed I considered driving it from the hard-drive activity LED. Using 17 LEDs means there is only the reset pin available unused, and using it for IO means you need to disable its reset function. Doing so means you need to use a HV programmer during development... I originally intended to leave the A port unused (only 15 LEDs), giving me two spare pins for control, but to be completely honest I was off-by-one with the loop in PostScript making the punch template and ended up with two extra LEDs to drive. :)

You could use one less LED or charlieplexing of course, but it would be extremely difficult to do the PWM over charlieplexing. The PWM is already pushing the timing constraints... I could write the code more efficiently I guess?



25th October 2010 04:06

Arv - K7HKL wrote...

May the Force Be With You.

Next possibly illogical step could be to use a short timer (much like a VOX circuit) driven by the HD access LED voltage to activate the scanner. This way your Cylon light would come on every time the hard drive was activated. That seems more interesting and less intrusive than just having it run all the time.



24th October 2010 22:00

Alan wrote...

Wooo an update! I like the solar-cell thingo, nice idea!

C'mon Al sixteen wires, I'd have thought you'd solder the LEDs straight on the edge of the PCB and hot-glue it behind the bezel and done your point-to-point goodness. :)

24th October 2010 16:07

Alan Yates wrote...

Indeed I am hanging out for the return of Caprica also.

Wow it is amazing what you can patent! The "breathing" LED for sleep thing has inspired a few other electronics hobbyists... Have you seen the sleepy pumpkin? (EMSL is also home of one of the more popular modern Larson Scanner kits.)

Just for fun I tried it myself using some code vaguely related to the PSK-31 beacon controller I've never really finished... It is sinusoidal which is a poor approximation of physiological breathing I guess.

24th October 2010 08:11

Peter Marks wrote...

You should get the flu more often. I love your passive LED monitor and had never read the Wikipedia Larson story. I'm looking forward to Caprica returning presumably next year.

Another interesting PWD LED pattern is the realistic breathing pattern that Apple uses when their devices sleep. Interestingly it is patented but clearly well thought out.

Leave a comment on this article.