Motion sensor light that latches on and off

PIR motion sensor instead photo transistor?

Hi MrDEB

When reading up on the photo transistor I realised that it only reacts to photons and won't sense my hand when in total darkness, therefore I believe I need a passive infrared motion sensor such as this one: PIR Sensor Module

However, I've no idea how to rearrange the circuit you drew for me to incorporate this - 3 wires instead of 2... I've bought the parts and put it together on a breadboard (all except the PIR motion sensor) and I bought the isolated triac for the AC but have it set up to light an LED instead for the moment as you suggested (see attached - I hope I've put it together right...).

Also, I'm concerned that because I plan to have the sensor facing downwards next to the light source that's also facing downwards that the light reflecting off the surface they're aimed at might actually trip off the motion sensor. Do you think this may happen?

Thanks again Mr DEB

Oliver

you don't need a PIR

the phototransistor will do the deed.
PIR will not work in the presense of light or sunlight.
with the PIR that is on motion sensing lights, the IR section shuts off usually with a photocell.
Using the circuit I posted should work.
you might have to do a little tweeking maybe, seeing how you want to point the sensor down. Why ??
If you bought the phototransistor, try connecting your ohm meter across the part and if you have the polarity right it will show some resistance. the resistance will go down in the absence of light (waving hand over sensor) thus turning the phototransistor off.
this is what you want. An on off on sequence as this will clock the flip flop.
hopfully you have an ohmmeter?
if not try connecting an LED/ resistor in series with the phototransistor and a battery.
the LED should light when you have light on the photo transistor.
if it dosn't then you may have something wired wrong.

Apologies if I'm confused but wouldn't the light turn on at night when I switch off the other lights in the room then?

you have a flip flop in the circuit

true in a sense
lights all go off at night the circuit is waiting for the light to come back on
when it does the light will come on
wave your hand over the sensor and the light should shut off
wave it again and light should come on
the light/dark/light sequence produces a clocking (like a push-button switch on/off/on)
with more circuitry you could build the unit with a disable circuit so when its dark for a period of time te unit will not light upon daylight but now your getting way over your head I assume. Would entail a micro controller.
just turn the light off upon daylight.