Here's a fun way to turn a light, fan or other electronics on or off by just clapping your hands!
BUILD TIME: 90 MINUTES
DIFFICULTY RATING: BEGINNER
Think about what electronics we turn on and off remotely in our modern day lives. From changing the TV channel from the comfort of the couch using an infrared remote control, to opening the garage door without getting out of the car, using a wireless remote.
Another way to turn things on and off is by clapping your hands. Imagine that! At the clap of your hands, you could turn your bedroom lamp off without getting out of your comfy bed. Alternatively, you could switch something on and off that is out of reach.
Let's show you how to build your own clap activated switch. We'll start things off simple, by turning an LED on and off, then show you how to add a relay to switch a low voltage light, fan, etc.
At the same time, you will learn about electronics and be introduced to the versatile 555 Timer, a transistor, and flip-flop Logic IC.
You may have an idea in mind already what you want to control, but we’ve included a lamp shade with stars cut-out to get you started.
|CRAFT MATERIALS & TOOLS REQUIRED:
|1 × Computer to Download the Illustrations
|1 × A4 Printer to Print the Illustrations
|1 × Pointy Nose Pliers to Bend the Legs of the Electronic Components
|1 × Pair of Scissors / Artwork Knife
|1 × Glue Stick
|1 × A4 Sheets of Cardboard (Thick)
|1 × Pack Blu-Tack / Tape etc.
|Markers, Pencils or Crayons (if using outlined versions for colouring)
CRAFT MATERIALS & TOOLS REQUIRED:
|ELECTRONIC PARTS REQUIRED:
|1 × Small Prototyping Breadboard
|1 × Electret Microphone with Pins
|1 × Mixed Jumper Wires
|1 × Breadboard Wire Links
|1 × 555 Timer IC
|1 × 4013 CMOS Flip Flop IC
|1 × BC547 Transistor
|1 × 5mm Green LED
|1 × 1uF Electrolytic Capacitor
|1 × 330Ω Resistor*
|1 × 1kΩ Resistor*
|1 × 47kΩ Resistor*
|1 × 100kΩ Resistor*
|1 × 4AA Battery Compartment
|4 × AA Batteries
|1 × Relay Module
|1 × High Brightness LED Module
*Quantity shown, may only be available in packs.
We’re assuming very little (or zero) electronics knowledge, and so will try to walk through everything carefully, in order to ensure your success. There is no soldering or programming required - we’ve kept it as simple as possible.
If this is your first project, you may also like to read “Breadboard Basics” in Issue 15, to familiarise yourself with the breadboard before getting started.
COLOURING & PREPARATION
The printable parts can be printed on any home printer on an A4 sheet. While these are not critically essential, it helps make the builds more fun than simply LEDs lighting up without any context.
We have provided a plain illustration for this projects. This is to allow you to either add-on the fun of colouring the cube lamp, or simply get on with the interactive portion. The choice is yours.
For this design, the white star lamp shade folds and glues together using regular 80gsm paper. If you have thicker paper then the lamp will be easier to assemble.
You could also glue your printed design onto some backing card to provide structural integrity. The cardboard should be thick enough to hold itself up, but not so thick you cannot easily cut it with scissors.
ELECTRONICS AND CONSTRUCTION
We will split the build into a few parts. First, we will build the electronics that turns an LED off and on. Then we will show you how to trigger a relay that switches a larger LED on and off. We'll also show you how you could connect other low voltage devices, such as a fan, with an external power supply.
Clap Activated LED Light
Let's build the electronics for our project. Below we will guide you step-by-step on how to wire up the electronics. If you are unsure about any of the connections, you can refer back to the Fritzing diagram shown below. This diagram shows you the holes the components and wires need to be plugged in to. We should also point out that it doesn't matter what colour wires you use.
Before we get started though, arrange all of the parts, tools and materials required. Make sure you have a clean workspace with good lighting.
Put the breadboard on the table in front of you. The side with the red (+) positive power rail should be at the top.
Insert the two wire links on the left that join the positive and negative power rails on top to the power rails on the bottom.
Gently insert the 8-pin 555 Timer IC into the breadboard as shown above, making sure you put it in the right way. The notch or circle indent on the top of the IC should point to the left side of the breadboard.
Tip: If the legs on the IC are splayed apart, making it difficult to insert into the breadboard, you can gently press the IC against a flat surface to make them straight.
Before you handle the 14-pin 4013 IC into the breadboard, it is important to be aware that they are static sensitive. That means that an electric shock, like what you get when you rub your feet on carpet, can damage the IC. Discharge yourself on a large metal table, metal door frame or object before you handle the IC. Long nose pliers is one easy way to handle the IC so you don’t need to touch the pins.
Gently insert the 14-pin 4013 IC into the breadboard, making sure you put it in the right way. The notch or circle indent on the top of the IC should point to the left side of the breadboard.
Insert the 47k resistor as shown above. It can go in either direction. A 47k resistor will have yellow-violet-orange-gold or yellow-violet-black-red-brown coloured bands on it depending if it has 4 or 5 colour bands.
Note: We have trimmed the legs of our resistor with cutters and bent the legs so it goes flush to the board.
Insert a short wire link as shown above.
Insert a short wire link as shown above that goes to the negative power rail.
Your microphone should have two pins. If you look closely, one of the pins will be joined to the round metal body. This is the negative (-) leg.
Insert two socket to plug jumper leads into the back of the microphone. Ideally, use a black or dark coloured wire on the negative (-) pin so you know which one to connect in the next step.
Insert the microphone leads into the breadboard as shown above. Make sure the negative wire from the microphone goes to the hole that joins to the negative rail on the breadboard.
Insert a short wire link as shown above that goes to the positive power rail.
Insert the short wire link as shown above.
Insert the 1k resistor. The colour bands will be brown-black-red-gold or brown-black-black-brown-brown depending if it has 4 or 5 colour bands. Resistors work in both directions so it doesn’t matter which way you put these in.
Insert the short wire link you see here that goes alongside the 1k resistor to the positive power rail on the breadboard.
Insert a short wire link from the 555 Timer IC to the positive rail.
Note: This forth leg on the IC is referred to as Pin 4.
Insert a wire lead from the 555 Timer IC to the negative power rail. This is Pin 1 on the IC.
Insert the 10k resistor from Positive to Pin 6 on the IC. The colour bands will be brown-black-orange-gold or brown-black-black-red-brown depending if it has 4 or 5 colour bands. Resistors work in both directions so it doesn’t matter which way you put these in.
Insert the short wire link that goes across the left side of the 555 Timer IC.
Insert a short wire link that goes to the second pin (Pin 2) on the 555 Timer IC.
Insert a very short link that joins Pin 6 and Pin 7 on the 555 Timer IC.
Tip: This is a small piece so using pliers can help.
Insert the BC547 Transistor as you see above. The flat side needs to point to the top of the the breadboard.
Insert the capacitor. The longer leg goes to the positive rail on the breadboard. The side with the stripe on the capacitor’s body points towards the two ICs.
Insert a short wire link shown above that joins the capacitor to the 10k resistor.
Insert the three wire links shown above that join pins 4, 6 and 7 of the 4013 IC to negative (-).
Insert the longer wire link shown above that joins pin 14 of the 4013 IC to the positive (+) power rail.
Insert a long wire link that joins pin 3 of the 555 Timer IC to pin 3 on the 4013 IC.
Insert the long wire link shown here that goes from pin 1 of the 4013 IC. Next, insert a short wire link between pin 2 and pin 5 of the same IC.
Insert the 330 Ohm resistor and green LED as shown above. The 330 Ohm resistor is orange-orange-brown-gold or orange-orange-black-black-brown. The short leg on the LED goes to the negative (-) power rail on the breadboard.
Connect power to the breadboard. Insert batteries into the battery holder and insert the red lead into the positive (+) rail and the black lead to the negative (-) rail. The LED should light up when you apply power. If you clap your hands loudly the light should turn off.
Attaching A Relay
In the previous project, we made a small LED turn on and off. But how do we control a brighter light or something similar that requires much more power to work? A bright light for example?
One way to control more power would be to use a transistor, like what we used in the previous project to amplify the sound from the Electret Microphone.
Another way is to use a relay. A relay is a mechanical switch. When you apply power to the coil inside the relay it turns into an electromagnet. That magnet makes the switch contacts in the relay turn on or off. Or in other words, the normally open (NO) switch closes when you apply power. When you remove power the relay switches back. The normally open contacts go open again.
Let us show you an example using a bright LED, which you can turn into a bedroom lamp.
Disconnect the battery power from the breadboard, then remove the LED and 330 Ohm resistor from the Breadboard.
Wire up the relay as shown using Pin to Socket jumper leads. Positive (+) on breadboard to VCC, negative (-) on breadboard to the GND, and the third wire from the breadboard to the IN or Signal pin depending on the markings on your relay.
Connect a pin to socket jumper lead from the negative rail on the breadboard to the negative (-) pin on the LED module.
Run a pin to socket jumper lead from the positive rail on the breadboard to the middle screw terminal on the relay. Run another pin to socket lead from the NO (normally open) screw terminal to the positive (+) leg on the LED.
Apply power again to the breadboard. Clap your hands and the large LED should turn on and off.
Important Note: This LED is very bright. Do not stare directly at the light. It also draws a lot of current so don’t leave it on for too long otherwise your batteries will go flat.
White Stars Lamp Shade
Now we will show you how to prepare and assemble the white star lamp shade. Some knife cutting is required, so adult supervision may be required (Or get mum and dad to do it for you).
Prepare the tools and materials to make the star printed design.
Very carefully cut out the stars using a hobby knife.
Very carefully cut out the box, making sure you do not cut off the glue tabs.
Crease all of the glue tabs.
Fold the box into a loose box shape.
Glue the inner tabs on the box design.
Assemble the box and ensure the tabs hold in place. Leave to dry.
Insert the LED module into the large star on the box.
Congratulations, you have just made your very own clap activated switch. If we break it down, you have made a simple little amplifier using a transistor to amplify the electret microphone signal, a timer circuit using the versatile 555 Timer IC, and a logic 'flip-flop' circuit using the 4013 IC.
In standby mode, the transistor is in the "off" state. When a loud clap is made close to the microphone, the transistor will turn "on" and triggers the 555 Timer IC. The 555 Timer IC will then send a positive voltage pulse to activate the 4013 IC, then returns to its low voltage state to wait for another clap.
The 4013 IC is called a 'Positive Edge Triggered D-type Flip-Flop'. To generalise how it works, each time it gets a positive pulse on its input, it toggles the state of both output pins, hence 'flip-flop'. The output stays in that high or low voltage state until it gets another positive pulse on the input. This output makes our LED or relay turn on or off
WHERE TO FROM HERE?
If you built the second project with the relay and bright LED light you may find the batteries go flat too soon if you leave the light on for too long. In this case, you could replace the battery pack with a 5VDC 1A or higher mains power adaptor.
You could turn other devices on and off using the relay. For example, you could control a 12V fan. As shown in the diagram here, you would use an external power supply (large battery or mains power adaptor) and have the positive power lead run through the relay. A word of caution: please keep to using low DC voltages only. NEVER handle AC mains power to avoid being electrocuted.
- Check over all of the components and links that they go into the same holes as shown in the Fritzing diagram.
- Ensure you are using fresh batteries.
- Check that the microphone is in the correct way.
- Check that the pins of the microphone are making contact with the breadboard
- Make sure the 555 Timer IC and 4013 IC are in the correct way with the notches facing to the left.
- Check that the capacitor is in the correct way
- The microphone may be low spec and not sensitive enough. Try a microphone from another electronics retailer.