Light programming with a photoresistor and flashing computer monitor

[lacettis]

Really nice idea! I like it! I have a question... the reference voltage of the logic high from the ldr is fixed or you define it each time you use the system? because in any different environment it's possible to have different values... you know what I mean... Maybe if you isolated the ldr then it would be worked more accurately...

[Henry00guy]

This is very nice, I never figured that such a thing would work, especially given the fact that it was bright in the room, the LCD monitor doesn't really flash, you might want to try an old TV instead in a darker room, that will be much more reactive

[benryves]

Interesting stuff, and it reminds me of the Timex Datalink watches that used a similar system for transferring data. I was under the impression that LDRs reacted to changes in light intensity more slowly than a photodiode - have you tried using a photodiode instead? Without an oscilloscope it can be hard to debug that sort of thing, though at such low frequencies I imagine a soundcard oscilloscope (e.g. Visual Analyser) would be sufficient.

[Henry00guy]

Hooray Ben Ryves was here, I'm a fan!