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Automatic Dimming Nightlight

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In this project, I designed a nightlight that automatically dims and turns itself off. A lot of people find it difficult to fall asleep when they suddenly transition from a brightly lit room to complete darkness. A dim source of light such as a nightlight helps them to adjust to a lower brightness and fall asleep more easily. But the down side of most nightlights is that they waste electricity because they are on all night when you really only need them to be on while you are falling asleep. So I designed a nightlight that will automatically dim and turn itself off after a certain period of time that is set by the user
 
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Step 1: Materials

Picture of Materials
Materials:
Jumper wires
Printed circuit board
IC1: 741 OP AMP
IC2: 741 OP AMP
Terminal Connectors
R1: 1MΩ
R2: 5kΩ variable
R3: 2.2kΩ
R4: 3.3MΩ
C1: 2200µF 10V
C2: 2200µF 10V
D1: 1N4001
D2: D3: D4: 3.5V LED
S1: SPST latching switch
S2: momentary switch
Plastic project box
T1: 6V 400mA DC power supply
It may also be helpful to have some glue and heat shrink tubing.

Tools:
Drill
Soldering Iron
Wire cutters
Pliers
Screw driver
nfernandez511 months ago
Thank you very much! Your explanation was really helpful.
nfernandez511 months ago
a very good idea-proyect :)
I only have one question, how do you power the 741? its supposed they must be powered with a dual voltage supply
DIY Hacks and How Tos (author)  nfernandez511 months ago
Dual power supplies are only needed if you want to be able to output positive and negative signals such as in a pure AC signal. When working only with DC, a single positive supply is fine.
jpedro41 year ago
Sir can i use 5V DC?.. what do you mean is has an operating voltage of 9.8V?..where can i get that?.. my light source cannot cannot more than one..please help me
jpedro41 year ago
is the power supply connected to the outlet all night?.. is that ok?..
DIY Hacks and How Tos (author)  jpedro41 year ago
Yes. I have been using it for over a year with no problems. It does use a little power by being plugged in but it is perfectly safe.
jim5150jvc2 years ago
neat project! what should the voltages of those 2200µF capacitors be?
You're right. I did forget to mention that. I will update the materials list to include that. It doesn't really matter as long as they are rated for more than the supply voltage. The power supply that I used had an operating voltage of a about 9.6-9.8V with this circuit. So I just used a couple of 10V capacitors.
Transquesta2 years ago
Forget the circuit, where can I get one of those cool lanterns? :-)
I think that we got that one from Earth Bound a couple of years ago. They have a number of similar lanterns in stock most of the time. But once or twice a year they will go on clearance for half price. We also found some similar ones at World Market last year.
Xenophon2 years ago
Very cool project and I'm totally digging that lantern.

As much space as it provides, I would look at making two more lights on the same pattern, but with differently colored LEDs. Putting them all on different time differentials with the variable resistor would make an impressive light show in the room as they all faded away.
DIY Hacks and How Tos (author)  Xenophon2 years ago
I find that it is a lot cheaper to buy super bright white LEDs. Then you can color them yourself to whatever you want. Liquid highlighters work fairly well for that.
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