In this instructable i hope to be able to show you how to make a simple toy piano using a 555 timer ic and a few basic components. This my first electronics project on perfboard and there are probably much more sensible ways of laying out the parts, it would have been easier to set them apart more but i didnt do that.
Step 1: What You'll Need
6 x 1K resistors
6 x small buttons
1 x 10k resistor
10u and a 100n capacitor
555 timer chip
small piece of perfboard
battery clip and switch
solder + iron
470 ohm resistor and a led
Step 2: Breadboard
I started of by making the circuit on a breadboardso i could see how it worked and how to fit it onto the perfboard
Step 3: Adding the Chip
i soldered the ic straight onto the board, it would have been more sensible to use a socket to plug it into but i didnt have one.in this step i also soldered the 10u capacitor onto pin 3, they are connected by a solder bridge on the bottom of the board. be careful with the polarity of the capacitor, the longer lead is the positive end and this is attached to pin 3, the negative end also has a grey stripe on to show its negative, putting it in the wrong way round can damage the capacitor.
the pins on an ic dont go from left to right they go anticlockwise around the chip starting at the pin with the circle above it
Step 4: Adding the Buttons
i first layed out the buttons in a line across the top. i had to leave room for the resistors to go along the top so i left two spare rows above the buttons.i used the leads i had cut of the capacitor to connect the negatives of the buttons.
Step 5: Resistors
to make the piano work you need to add the 1k resistors between the points of the button. Then use a solder bridge to conect the parts up underneath the board
Step 6: 10k Resistor
i conected the 10k resistor to the last button. the black circles represent where the battery leads are going to go
i added a jumper wire from pin 7 to a hole next to the 10k resistor, i added the last 1k resistor and soldered it next to he end of the jumper wire and connected them all together with a solder bridge, i used one of the legs of the resistor to conect the jumper, 10k resistor and the 1k resistor to a hole next to where the positive battery lead will go
Step 8: More Jumpers
i attached jumpers going up to the positive terminal from pins 4 and 8. i will make a solder bridge underneath the board to connect together all the wires that need to be attached to ground
Step 9: Pins 2 and 6
pins 2 and 6 need to be connected and then attachd to the negative end of the buttons. the 100n capacitor is also placed beside the two jumpers. th lead from th capacitor is bent down and used to conect to another lead which is connected to ground.i used this lead as a ground rail.
Step 10: Attaching Pin 1 to Gound
ran out of space on top of the board so a jumper so i connected pin 1 to the ground wire using a jumper under the board
Step 11: The Speaker
i attached the speaker to pin 3 of the chip through the 10u capacitor, and put the other wire through a hole above the ground wire and soldered it in.
Step 12: Adding Power
put the wires from the battery holder into the board. into the black holes we marked earlier. the positive goes in the left hole,negative in the right. Solder them in. Make a solder bridge between the round wire and the negative wire you just soldered in and solder all the wires that come from positive in the diagram (1k resistor, pins 8 and 4) together with a solder ridge
Step 13: Testing
It now should work, check all your joints and work through the schematic, making sure you put it together right, then take a deep breath and plug in the battery... It should make a noise when you push one off the buttons, if not then check everything is right, eg. is the capaciter the right way round? 555 ic upside down? if it stll doesnt work then the components might be faulty.
Step 14: Adding a Switch
Cut he red wire between the battery and the board, strip the ends and solder them to the prongs of a switch. one to the middle and one to the outside prong. You should cover the joints in heat shrink tubing or tape to make them stronger
Step 15: Adding a Led
Adding an led that shows when it is on is useful as this circuit gives of no sound when i not being played, a led will stop you forgetting to turn it off. Solder the resistr to the positive terminal and the other end to the positive lead of the led (the longer one). Then take the other lead and solder it onto the ground. the led should come on when the device is powered
Step 16: Finishing Of
This circuit is incredibly easy to modify as its so simple, you could replace a resistor with a LDR to create a solar therimin, or change the resistor values to get different pitches