SECURITY BOX

To understand the concepts of open and closed circuits.

SKILLS LEARNED:

Construction of Simple Circuits
How to Solder
Differences between normally open and normally closed switches

TIME:      One hour.

INSTRUCTOR NEEDS:

One volunteer per five 4-Hers.

SKILLS:

Knowledge of simple circuits, switch configurations, and soldering experience.

PARTS LIST:
9V battery
SPDT lever switch
SPST mini-slide switch
9- or 12-volt buzzer with leads
9V battery clip (terminal connected)
9V battery holder
Pencil box
All electrical supplies are available at any electronic hobby store.

COST: $ 6.50

TOOLS & SUPPLIES:
Soldering iron
Resin Solder
Hot Glue Gun
Glue Sticks
Extra 22 AWG wire (for mistakes)
Wire Strippers

When the circuit is closed (both switches closed) electricity has a complete path and the buzzer sounds. If either switch is in the open position the path is broken and the circuit will not sound.

The lever switch can be operated in two positions:
 

1. Normally closed (N.C.) - When the lever is up (lid open) this switch is closed, the path is complete, and the buzzer sounds.

 
2. Normally open (N.O.) - When the lever is up (lid open) the switch is open, the path is broken, and the buzzer will not sound. Had we used the (N.O.) terminal, when the lid was closed, the switch is closed; the path is complete, and the buzzer sounds.

2. Attach red lead from the battery clip to a terminal on the SPST mini-slide switch. Solder the connection. Be careful! Soldering irons are hot!

3. Attach red lead from the buzzer to the remaining terminal on the SPST mini-slide switch. Solder the connection.

4. Attach black lead from the buzzer to the NC (Normally Closed) terminal of the SPDT lever switch. Solder the connection.

5. Attach black lead from the battery clip to the COM terminal of the SPDT lever switch. Solder the connection.

6. Hot glue the battery holder to the side of the box. Be careful! Glue guns are hot!

7. Glue the buzzer to the side of the box so that it is positioned approximately 1/4 inch from the box bottom.

8. Glue the SPST mini-slide switch to the side of the box above the buzzer. Make sure the box lid will close without hitting the mini switch.

9. Glue the SPDT lever switch to the side of the box, such that approximately 1/8 inch of the lever extends above the top. Make sure the lever is compressed when the lid is closed.

10. Insert the 9V battery into the battery holder and attach the battery clip.

11. Test the security box by raising and lowering the lid. The circuit can be turned on and off by using the SPST mini-slide switch.

Troubleshooting
1. Check the battery.
2. Check the mini-slide switch for the on position.
3. Make sure the lever is compressed with the lid closed.
4. Make sure red leads are attached to the mini-slide switch.
5. Check for good solder connections.