I bought a new door chime which has a glass cover. I want to add an LED inside to act as a night light. The door chime runs on a 16v transformer. Can I just buy a premade plug in night light and cannibalize it for the sensor, then add my own LED's?

 

It depends on your skill level. A far as I know, you can't buy a 16 volt night light. A night-only LED circuit is a bit complicated.

 

Yeah either 12v or 24v but I threw a 24v led on it and it seemed to light alright. Do you think I would be able to re-purpose one from something else? Like a outdoor solar light or something of that nature?

 

The way you phrase your question tells me that you don't understand that a night sensing circuit can be cannibalized from almost anything.

There are night sensing circuits on this site and probably on Google. Could you do this job if somebody handed you the circuit drawing?

 

Ya I'm actually pretty good at soldering and following instructions. Fixed many things in my life by reading then doing. I never tried looking up "night sensing circuit" but I'll do that now and maybe I'll find one already made up that I can use.

 

Found this http://www.instructables.com/id/Simple-circuit-for-every-electronic-beginers-Autom/ He says it works from 3-12volts. Would I be able to copy this but use resisters to lower the voltage from 16v to 12v?

 

Can you do the diodes to turn your 16 volts AC into DC?

 

You mean something like this? http://www.instructables.com/id/AC-to-DC-converterdiode-bridge/

 

This seems to be turning out like this:

 

Thanks! I'll have to order some parts. I wish I understood more about all the components. So does it matter what size of transistor or diodes I use?

*Edit* I gotta look up certain symbols as well. I'm not familiar with a couple on the diagram.

 

The 680 ohms 1/2 watt is to limit the LED current to 20 milliamps. Since you need that size, buy 2 and use one to protect the transistor from the adjuster.

As for the transistor, any P.O.S will do. 2N3904, 2N2222, whatever you can find.
The diodes are 1N4001 to 1N4007 or any quad rectifier chip you can buy. They don't make any rectifier diodes that can't do this.

 

Thanks so much, just went through and labelled the diagram so I don't get mixed up. The only thing that still confuses me is how to wire the potentiometer. I'll do some googling and hopefully it works when I'm done haha. I'll report back when I get it all soldered together.

 

Just short the middle terminal to one of the ends. If it works backwards, move the short to the other end.

Stupid, but practical.

 

Perfect. Found this rectifier that should work. http://www.ebay.ca/itm/AC-DC-Conver...t=LH_DefaultDomain_0&var=&hash=item3aa5d234f7

Oh and what's the max wattage for my LED? Or can I just not exceed 20 milliamps?

 

WRONG!
That one has a capacitor. Do you see any capacitors in the drawing?
I designed this as a pulse operated circuit. If you add a capacitor the resistors must be changed to 1000 ohms 1 watt and the transistor might smoke.

 

Glad I asked first! I'll just build one according to the diagram. Just ordered my breadboard.

 

Well I have the circuit built. I still have to add some spades or other quick connects on the the leads but it works. Here's a photo in case you want to see. I also have to trim the bread board.

I originally thought it didn't work as the led I bought wouldn't turn on. I later tried a couple of 6v ba9s base led bulbs and they lit up no problem. Here's a link to the one that didn't work maybe I chose the wrong kind of bulb. http://www.dx.com/p/g4-1w-100lm-6-s...nt-light-reading-lamp-12v-320436#.VUrYi5NMehw

The ba9s socket bulbs work but they are pretty directional. Any suggestions on two led bulbs that would work and have better light dispersion?

Thanks again for the help with this project!