Activity 4
Making Sound Electronically
Background Information
Wiring and testing electronic circuits is easy with the socket board. There’s no soldering! Look at the drawing of the board on page 211. To facilitate wiring integrated circuits, certain sets of sockets are connected together inside the board. All sockets in row “x” are connected, as are all sockets in row “y.” (but these rows are not connected to each other). Typically the positive battery voltage is applied to one of these rows, and the ground—the negative side of the battery—is applied to the other. Within each column, sockets A through E are connected, as are sockets F through J (again, the two sets are not connected to each other). These connections facilitate wiring to an integrated circuit (IC). Look at the the drawing on page 211. For example, to connect a wire to pin 1, the pin at the lower left of the IC (in socket F5), the wire could go in any of sockets G5, H5, I5, and J5, which are all wired to each other and to F5. Notice that the sockets are made for solid wire. Stranded wire is not stiff enough to be pushed into the socket. Consequently, you must solder a short piece of solid wire to each end of the battery clip wires.
The 555 timer is an extraordinarily flexible integrated circuit. Constructing an oscillator requires only a few resistors and capacitors. Values of these resistors and capacitors control the frequency of the wave produced. The basic idea of the operation is straightforward. The resistors and capacitors mentioned above form an RC circuit across the battery. (See the circuit diagram on page 214). This circuit is connected into the 555, which can sense the voltages across the resistors and on the capacitor, as shown. The battery begins to charge the capacitor. When the voltage on the capacitor reaches 2/3 of the battery voltage, the 555 begins to discharge the capacitor. When the voltage has fallen to 1/3 of the battery voltage, the 555 stops the discharge and allows the capacitor to recharge again. These regular changes in voltage provide the oscillator output. For further information, see the reference books in Program Resources.
To read the circuit diagram on page 214, your students will need to know how the pins of the 555 are numbered. The pin nearest the dot is pin 1. The other pins are numbered consecutively proceeding counterclockwise around the chip, as shown in the drawing. Note that students will need these pin numbers to answer Question 3 of Physics To Go.
The symbol at the lower right in the drawing on page 214 is the ground. Although not shown in the drawing, the ground is understood to be connected to the negative side of the battery. The “+9-V” arrow at the top goes to the positive side of the battery.
The point where this arrow crosses the line from the 100 k resistor to pin 4 is a connection between two wires, so +9-V is connected to pins 8 and 4 and also to one side of the 100 k resistor. Pins 2 and 6 are connected together and connected to one side of the 10 k resistor. Ground is connected to the negative side of the 4.7 μ f capacitor, to pin 1, and also to one side of the other capacitor.
Making Sound Electronically
Background Information
Wiring and testing electronic circuits is easy with the socket board. There’s no soldering! Look at the drawing of the board on page 211. To facilitate wiring integrated circuits, certain sets of sockets are connected together inside the board. All sockets in row “x” are connected, as are all sockets in row “y.” (but these rows are not connected to each other). Typically the positive battery voltage is applied to one of these rows, and the ground—the negative side of the battery—is applied to the other. Within each column, sockets A through E are connected, as are sockets F through J (again, the two sets are not connected to each other). These connections facilitate wiring to an integrated circuit (IC). Look at the the drawing on page 211. For example, to connect a wire to pin 1, the pin at the lower left of the IC (in socket F5), the wire could go in any of sockets G5, H5, I5, and J5, which are all wired to each other and to F5. Notice that the sockets are made for solid wire. Stranded wire is not stiff enough to be pushed into the socket. Consequently, you must solder a short piece of solid wire to each end of the battery clip wires.
The 555 timer is an extraordinarily flexible integrated circuit. Constructing an oscillator requires only a few resistors and capacitors. Values of these resistors and capacitors control the frequency of the wave produced. The basic idea of the operation is straightforward. The resistors and capacitors mentioned above form an RC circuit across the battery. (See the circuit diagram on page 214). This circuit is connected into the 555, which can sense the voltages across the resistors and on the capacitor, as shown. The battery begins to charge the capacitor. When the voltage on the capacitor reaches 2/3 of the battery voltage, the 555 begins to discharge the capacitor. When the voltage has fallen to 1/3 of the battery voltage, the 555 stops the discharge and allows the capacitor to recharge again. These regular changes in voltage provide the oscillator output. For further information, see the reference books in Program Resources.
To read the circuit diagram on page 214, your students will need to know how the pins of the 555 are numbered. The pin nearest the dot is pin 1. The other pins are numbered consecutively proceeding counterclockwise around the chip, as shown in the drawing. Note that students will need these pin numbers to answer Question 3 of Physics To Go.The symbol at the lower right in the drawing on page 214 is the ground. Although not shown in the drawing, the ground is understood to be connected to the negative side of the battery. The “+9-V” arrow at the top goes to the positive side of the battery.
The point where this arrow crosses the line from the 100 k resistor to pin 4 is a connection between two wires, so +9-V is connected to pins 8 and 4 and also to one side of the 100 k resistor. Pins 2 and 6 are connected together and connected to one side of the 10 k resistor. Ground is connected to the negative side of the 4.7 μ f capacitor, to pin 1, and also to one side of the other capacitor.