A different kind of motion sensing security light?

I agree that he has the highest potential of success using microwave, or such. But what you describe is usually AC coupled output and you're back to standing still not showing up. You could DC couple the detector, 'remember' the level coming out when nothing is there, and simply go from there, with a cheap ADC and map back into a DAC that runs the lighting.

If you're going mechanical, why not make it a capacitive sensor. Chopping the field from the intruder. Since you kknow the speed of the chopping, you can synchronously detect and obtain EXACTLY the type of signal you want. ...I think.

Google produces 280 results for my "Tonal Voltmeter". I'm sure it was just that, using a photodiode to vary resistance/voltage. It looked like a clear T1 LED. I have nothing left (except fond memories) from experimenting with electronics.

Yes?

As I said in two prior separate replies... I am FWIW satisfied with the discussion. I will probably use a cheap motion detector, and maybe try to shorten the on-time so that the light blinks while motion is being sensed.

If you mean PIR motion detectors, they usually have twin element pyrometers (thin film thermistor) a motion of a IR source (person) is "grated" to produce a gross change from one element to the other - this is done in various ways such as Freznel type lenses (special IR transparent material) and faceted surface reflecting reflectors.

Most of the examples I pulled apart and hand traced the circuit years ago, were based on the LM324.

That's strange that you would call them thermistors? TO me a thermistor is a slow reacting device? But yet we have an application where we use a basic pyroelectric 3 wire detector for detecting vibration of small conductor as it exits from an induction heater. This vibration can get up to around 1khz or more when the wire snaps for what ever reason.

I would think a thermistor device would be a little slow for this wouldn't you?

Maybe the units I used have different smoke in side.

Jamie

AIUI they are closer to capacitor than resistor, the device does sense its own temperature though, they detect remote temperature by black-body radiation changing the temperature of the sensor.

TO me a thermistor

if you could make it thin enough it would work.

I have some continuity/voltage checkers with a thin film PTC in series with an inverse parallel pair of high efficiency LEDs (2mA rating) - the series PTC thermistor can react fast enough to protect the LEDs from application to voltages upto 450V.

Your usual disingenuous self!

My point is that a thin film thermistor can have a very fast response time - there was no need to be specific exactly what material the thin film was.

Wriggle wriggle!