Many people find the beep of an alarm clock to be a very unpleasant way to wake up. One alternative is to use lights to wake you up. For instance, a "sunrise alarm clock" gradually increases the brightness of a light near your bed at the set time. This helps some people to wake up more gently.
So in this project I am going to show you how to build a light alarm circuit from a outlet timer and a hand full of basic electrical components.
Step 1: Materials
AC Light Timer
USB AC Adapter
1 Mohm Resistor
4 X 100 ohm Resistor
10 kohm Potentiometer (Variable Resistor)
1000 µF Capacitor
4 X LED
Printed Circuit Board
Extension Wire (optional)
Momentary Switch (optional)
You will also want to have the following tools at hand:
Soldering Iron and Solder
Step 2: The Circuit
The potentiometer (variable resistor) is used to adjust the starting voltage of the capacitor. This effectively lets you set the initial brightness of the LEDs. Without it, the LEDs would be off for a long period of charging before the output would be high enough for LEDs to begin to emit light.
The values of the 1000 µF capacitor and the 1 Mohm resistor were arbitrarily chosen for convenience. Increasing either of these values will slow down the charging process and cause the LEDs to brighten more slowly. Decreasing either of these values will have the opposite effect.
The IRF510 MOSFET was chosen for the transistor because it requires very little input current and is capable of driving a large number of LEDs.
Optionally, you can connect a normally open momentary switch to the two terminals of the capacitor to act as a snooze button. Pressing the button will drain the capacitor and restart the charging cycle.
Step 3: Assemble the Circuit
After testing the circuit to make sure that everything was functioning properly, I soldered the circuit together on a printed circuit board. I decided to add a few more LEDs to make it a little brighter. Then I trimmed the circuit board to fit. Depending on how you plan to mount the lights, you may wish to add additional wire so that you can reach areas that are further away from the outlet.