Not any nastier than driving a relay straight off of a speaker signal.That is so nasty. Do you design stuff for Amstrad?
No, I don't and never have worked for Amstrad.
Those little circuits are ones that I've used before when the only signal available is audio and I need to switch something based on it. Not necessarily cameras. Simple noise activation for a recorder or a baby monitor type thing.
If you think that circuit is warped, you ought to see what I do with an LM3909 and a TTL 7473.
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By preference, though, I'd rather use something like a 555 timer or a purpose built debounce chip (they are commerically available.) If you use surface mount parts (can't EVERYBODY solder 0402 sized parts by hand?) you can mount the whole shebang inside the radio and power the circuit from its batteries. Makes it nice and slick. Sometimes, though, cheap and dirty's where it's at.
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