I want to light a miniature house …not “doll house” that can be played with , but the models like the period miniatures found in museums.
The lights in all rooms should come on simultaneously but slowly, over a period of say, 2-5 seconds when a viewer comes within 12-15 inches of the model. I don’t want the lights going on simply when someone walks past the model at 3 feet away.
Lights should stay on as long as the person is within that 12-15” distance, then fade out slowly, again, over about 2- 5 seconds as they move away. If another viewer comes up while the first moves away, and the lights dim a bit before lighting up again, or stay on, either way is OK.
Now for some background. I don’t know much about circuits. My dad (deceased) was a EE and I sometimes watched him tinker with stuff and asked questions. Then I took a basic Electronic course in junior college, but that was many moons ago. I do remember some principles and terminology.
I came across a design called a “Fade-in, fade out “ ckt for LEDS.
( Link attached)
It’s the first ckt shown, with the “slight flaw”
I bought some breadboard stuff and the parts on the parts list and used a 12v charger to power it. But I used a 2N2222 because my dad had a lot of those around.
The fade out works better, but the “fade in” is a little fast, but at least not like the typical LED sudden turn on (and off) .
Then I googled a lot on sensors and came across this Sharp sensor GP2Y0A02YK which seemed what I wanted. It’s weak at 3ft but seems to put out enough voltage at about 12-15 inches.
What I don’t know (and finally have come to my problem) is how to make this turn on and off the fader ckt.
I decided to try this: make the Sensor output turn on a second transistor (also NPN 2N2222-- which I will call NPN-2 ) and put the entire fader ckt as the load in the NPN-2 collector . I really had/ have no idea if this is correct, but I figured a load is a load if there is enough current to make it work.
The 12 v charger is the Vcc ( I took the push button switch out of the Fader ckt and just made the 12v go straight to the resistor R1) , and made all the common points of the fader ckt go to the NPN-2 collector.
The NPN-2 emitter goes to 12v charger low side The Sensor module itself is powered by 4 AA’s and its output goes to the NPN-2 base to turn it on (or not). And surprise of surprises, the whole thing actually works! Well, not great, but pretty well. So my questions are these.
1) Do I need resistor(s) in the base of NPN-2? It seems to work with one and without one. If I should have one/some there, what do I need?
2) How do I power the sensor module off the charger since it only needs 6v and not 12v?
3) How can I slow down the fade-in a little more ?
4) ) Is there a better way to do this? I.e. a better design, better sensor, just scrap the whole thing and start over?.
And finally 5) You all can stop rolling your eyes now.