Thread: Anyone a small circuit (electronics) genius?

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All I want is Simple, I think. But I do not know electronics.

I have some gargoyles. I want to modify them have 2 (two) small LED eyes that run off of a single 9volt battery. These will be on the roof, so I want them to come on automatically at dark, and off at light. I didn;t think this was hard.

I have been searching on the web, and I ahve not come across anyone who has done this apparently. Nothing simple out there, and every page left me more confused than the last.

So anyone?

Well, a sorta-simple (not technical but not cheap either) way would be to buy a light detector adapter that turns porch lights on at dusk, screw it into an unused light socket, screw in a plug adapter to the other end, plug in an extension cord to the plug adapter, a 9-volt transformer (wall-wart) into the extension cord, and an LED kit into the 9-volt adapter.

Did you get all that?

Now, if you can handle a soldering iron, check out the other posts after mine...

It's a fairly simple thing to do. All you need is 2 LEDs, a resistor, and a 9v battery connector. 2 LEDs will run for weeks on a 9v battery. All parts should be avalible at your local Radio Shack if yours is one that actualy still has parts! Here's a site to help design the circuit for you. http://led.linear1.org/led.wiz The information you need to input should be printed on the LED package.
Oh, and by NO means am I a genius, but there are some here!

So, the resistor is what makes it all turn on automagically when it gets dark and turn off again the next morning? Is that the doo-hickey with the smoke in it?

here is a link on how to build the circuit,http://hackedgadgets.com/2006/04/12/...-blue-bawls/2/

he uses an led to light up a bottle. on when dark off when light. hope this helps

Wow, that last link had ne all excited until i got to the second resistor.
I know when you are hooking up LEDs to a 9 volt, a single resister is needed but it['s size is varied depending on the LEDS. Now this has a transistor and a second resister. What determines the size of that?

Pssssst....Spookineer IS a genius...I've seen his Sinisterspace page...check if you don't believe me. Awesome.

Originally Posted by cruizer

Wow, that last link had ne all excited until i got to the second resistor.
I know when you are hooking up LEDs to a 9 volt, a single resister is needed but it['s size is varied depending on the LEDS. Now this has a transistor and a second resister. What determines the size of that?

He has all the parts listed... the transistor is an electronic switch.

With the photocell in place and when it senses light, it completes the circuit turning
the transistor on which turns the light off.

When the photocell turns off, it turns the transistor off thus switching the LED off.

Originally Posted by guitarist155

here is a link on how to build the circuit,http://hackedgadgets.com/2006/04/12/...-blue-bawls/2/

he uses an led to light up a bottle. on when dark off when light. hope this helps

OK, so I finally got around to building this circuit.

i think there are some problems with it. Forst off, me.

So this circuit shows how to do it with exactly what he has. And this guy gives you the parts list to buy from, well him.

Problem is, he uses one LED. Doesn't even tell you what the specs are on it.

I have two props using 2 LEDs, and one prop using 6 (maybe 8 if Radio Shack gets their butt together). That circuit does not work for what I am trying to do. In fact, I can''t get it to work at all, because I don't know what resistors are needed for MY specific application.

So I need more info, or a new idea.

hmmm i believe you would build the circuit as normal with the battery the resistor and the 2 leds once you have that working you would wire in the transistor like a switch according to the diagram on that page, he says the second resistor is varied depending on the photo cell used.
" Depending on the resistance of the photo-cell that is used the 100K ohm resistor may need to be larger or smaller. If the resistance is not correct the circuit may not function properly. For example if it is light it may stay on or if it is dark if may stay off. To find the best value you could use a potentiometer to vary the resistance until the best value is found."

i would just build the circuit for the 2 leds then add the second part other wise you will never know where the problem is.