Introduction: Shake Activated Water Bottle Night Light
This project turns your bedside bottle of water into a lantern with just a shake. That's right, we added a light...to the bottle. This project isn't just cool because it makes your water bottle look like a video game power-up, it is also super practical. No more ping-ponging down a dark hallway to the bathroom, or annihilating your big toe on one of those horrible metal feet under your bed. Maybe you dropped your lip balm or teddy bear. Maybe, after an evening of reading creepy-pasta, you need to check, IMMEDIATELY, to make sure that there is not a tall, slender-ish figure lurking in your closet.
In this tutorial we walk through the steps to make a light-up water bottle that ---
1. Is activated when you shake it.
2. Has the ability to change light intensity.
3. Has the ability to change the time it stays on.
4. And has an emergency bypass mode to just keep the bottle lit until deactivated.
Step 1: Materials and Tools Needed
A clear water bottle (any clear plastic water bottle will do.)
Drill with bits
Hacksaw blade with handle
Soldering iron & solder
Measuring tools, tape measure, ruler, caliper
Hot glue gun
Heat gun or mini torch (for the heat shrink tubing)
Small flat tip screwdriver
Step 2: Modifying the Base for the Control Components
We are using a round Sistema container to house all the parts to make this work. We have to make some holes in it for all the controls.
Here are the controls and what tools are needed to make the ports.
1. 100k potentiometer for determining the time the light stays on - needs a ½” hole in the side. Use a small drill bit and work your way up to ½”. (Use a deburring tool or hobby knife to remove any hanging bits of plastic.)
2. 25K potentiometer for adjusting the brightness – needs a 3/8” hole. Do the same steps as in #1.
3. [Shown in pics above, red button] On button (switch) – needs a ½” hole.
4. [show in the pics above] “On light” – needs a ¼” hole.
5. Emergency light "on button" – needs a ½” hole. Place this switch away from the main controls to differentiate it easier. In the dark, you don’t want to have to figure out which is which. The complete opposite side is a good place to start.
6. Drill 1/2" hole to place the USB charger port.
Step 3: Wiring the Control Components
The buttons in the base (Sistema container) need wire leads put on them.Some of these components also need pins soldered onto the end of their wire leads. These pins will be pushed into specific points on the breadboards to connect the components to the control circuitry.
Parts that need pins on their wire leads
- 25K potentiometer
- 100k potentiometer
- tilt switch
- green panel mount LED
- 5watt LED
- 470uF capacitor
For this project, solder 20 gauge stranded core wire to each of the components connection points. We use stranded core wire for this step because is flexes and is much more pliable than solid core wire. Add heat-shrink tubing to cover the exposed solder points. Use a torch or heat-gun to ‘shrink’ the tubing. One trick to get pins for the parts that need them, it to use your wire cutter to cut the leads off of any extra parts you have laying about. We show a capacitor being sacrificed for this purpose.
Note that the panel mount LED has its current limiting 10k ohm resistor soldered directly to one of its pins and then covered with heat-shrink tubing.
Step 4: Install Controls, Place Into Holes
Each control component is placed in their specific holes and a nut is screwed on to hold each in place.
Shown in the picture are more components... Those are addressed in later steps.
Step 5: The Schematic, Simulation
We approximated the Shake Night Light Water Bottle here. The 4 "AA" batteries is being used to product the Li-Po battery and boost circuit, making about 6V.
- Top left slider switch is the on-switch.
- Bottom left button is the tilt-switch.
- Bottom right button is the "emergency button"
- The top potentiometer adjusts the brightness.
- The bottom right potentiometer adjusts the time duration.
Step 6: Wiring Up the One-shot
Wire up the one-shot (on-time delay) circuit. Use the 22 gauge solid core wire for this. The solid core wire pushed nicely into the breadboard.
Step 7: Wiring Up the PWM
Wire up the PWM circuit (LED dimming control circuit) on the red board.Again, use the 22 gauge solid core wire for this. Connect power between the breadboards with two short lengths of the 22 gauge solid core wire.
Step 8: The Tilt Switch (how It Works, Orientation Suggestions.)
The shake-to-activate function works because of the tilt switch in the circuit. The tilt switch we used has a small slug of metal or ball bearing inside a housing. When the switch is “tilted” in the right orientation, the ball(slug) slides down to what is now the bottom of the container and bridges two contacts inside the switch. These contacts are connected to the two pins coming out of the switch.
This tilt-switch activates the "one-shot" circuit which then activates the "PWM" circuit... powering the LED.
Placing the tilt switch vertical is the simplest way to make sure it doesn't activate accidentally. However, this means that the water bottle has to be tilted at least 90 degrees from vertical to get the tilt switch to activate the light.
Step 9: Wiring the Boost Circuit
The LiPo battery used in the bottle has a nominal value of 3.7V (4.2 fully charged).
The 5W LED is looking for a voltage between 6 and 7V. The boost circuits, "boosts" the output from the battery to the voltage levels that we need.
After you solder leads to the boost converter. Consolidate the leads with some short lengths of heat-shrink tubing. Next, use a piece of the 3/4" heat-shrink to cover the whole circuit board. Now use a hobby knife to cut away just enough of the heat-shrink tubing to expose the little adjustment screw on the blue potentiometer.We applied a small bit of yellow tape to the input side of the board for quick identification.
The last thing that must be done before we put this component to use is to adjust its output. Here is a short procedure for doing this.
- Connect a power source to the input side. The positive and negative inputs will be labelled on the board. A bench power supply is best, but any power source that is somewhat similar in voltage level to the battery pack will do.
- Use a voltmeter to measure the output voltage of the boost converter. The output is labelled just like the input.
- Turn the exposed potentiometer screw to adjust the output to about 6.5v. It does not have to be exact but definitely don't exceed 7 volts.
Step 10: Preparing the Adafruit USB LiIon/LiPoly Charger
Solder some stranded 20 gauge wire to the points on the board that are labelled GND and BAT. Then apply a some of the 3/4" heat-shrink tubing to cover the board. Finally plug in the micro USB right angle adapter.
Step 11: The LED, Thermal Cutoff, and Heatsink Wiring
The LED to use for this project is a 5W LED. Why? For the range of light level options. A 3W LED, at max, is too dim for this project. The 5W can be almost blinding at the highest level.
Due to the power level, a heat-sink is needed. The so-called “rule-of-thumb” for the size of heatsink is around 6” to 10” of surface area per Watt of power dissipated. For this project, the light isn’t on for very long (except in emergency mode), so the amount of heat generated should be high for a long period of time. Find a head sink with around a 1” square base, and ½” to 1” tall. The surface area of the fins should be enough for the short periods of time.
However, we will place in an emergency thermal cut-off switch in case the LED does get too hot.
Use thermal epoxy on both the LED and Thermal Switch and place them on the flat side of heat-sink.
We also took a channel and made a stand off that surrounded those two components. Originally, we were going to epoxy the whole LED module to the lid. Instead, the stand-off acts like a good way to block light from coming out of the side of the base container, instead pointing most of the light upward into the bottle.
Step 12: Placing Everything in the Container
Place the two breadboards into the center of the container. And lay the voltage boost circuit somewhere that fits. Connect the control wires as laid out in the schematic.
Connect the battery recharge circuit board to the USB right angle connector. Then connect the JST plug from the LiPo battery to mating jack on the Adafruit LiPo board.
Connect the LED and Thermal Switch module to the circuit, as in the schematic, and point the LED upward.
Step 13: Stuffing All the Wires!
This is the most unscientific step… stuffing all the wires down into the container.
The only suggestion here is be gentle. Being too rough here could cause a connection to pop out of the breadboards.
Step 14: Gluing the Water Bottle to a Lid. Suggestion on Bottle Types
Your circuit is ready for the water bottle and container lid.
Go to any store and find a clear water bottle that you like. Target has a lot of options. Choose a plastic bottle, if you can.
Use some clear plastic epoxy to attach the bottle to the lid.
Step 15: Attaching the Lid
Another unscientific step. Gently place the lid on top of the base. Make sure to not pitch any wires on the edges of the lid.
Step 16: Modes, Intensity and Time
When turned on, the green panel mount LED will activate very dimly. This indicates that the shake-light is ready for you to shake it and set the light off.
With the 100k potentiometers on the lowest setting, the shake-light will stay on for about 11 seconds. Turn the 100k pot all the way in the other direction and the shake-light will stay on for about 65 seconds. At any point while the light is activated, you can adjust the light intensity with the 25K potentiometer.
There is a secondary mode of operation. The emergency mode. With the water bottle “on button” switched on, press the rear emergency switch button. This will bypass the timer and PWM circuits and power the LED to its maximum value. It will stay on until switched off, the battery dies, or the thermal switch is activated due to a buildup of heat. Whichever comes first.
Step 17: Emergency Mode Demo
Showing off the emergency mode. If the system is turn on already, pressing this "emergency button" on the back will turn on the light permanently.
Step 18: Charging
That USB port wasn't for nothing. It connects to the USB LiIon/LiPoly charger, and to the battery.
Just plug it in like your cell phone. It charges off of a 5V USB wall charger and a micro-USB cable.
Step 19: What You Can Learn From This Tutorial
- Learn how to use a 5W LED.
- Building a one-shot timer circuit with a 555 timer IC.
- Building a dimmer, PWM, circuit with a 555 timer IC.
- Using a thermal switch.
- Using potentiometers for controls.
Step 20: Other Uses & Epilogue
The shake-light Isn't just for bedside use. This could come in handy absolutely anywhere. Imagine Hiking camping with it. Or trying to find the AC outlet behind a desk at work. What about all the times you needed a light to find something at the bottom of your backpack?
We love this concept, but there is clearly a lot of room for improvement. First off, the the base could be made much smaller. That would be fairly easy, since everything in the base is over sized. Sourcing smaller parts, soldering the circuits to a single perf-board, and 3D printing a shell just big enough for the task could maybe halve the size of the current build. Also, exchanging the simplicity of the 555 timers for a microcontroller would give more control over the light.