1. How a 555 Timer Works Objectives:
You will build a simple circuit to observe the operation of a 555 Timer.
This dot marks pin 1
555

2. Take Inventory of your Parts
You will need the following parts from your kit:
Breadboard
220 ohms resistor
6800 ohms resistor
16K ohms resistor
LED
10 uF Capacitor
555 Timer
9 volt battery lead
5 wires
9 volt battery

3. Use this schematic to construct the experiment.
Build the Circuit
Use this schematic to construct the experiment. +
6.8K Ohm
9 volts -
220 Ohm
16K Ohm 3 6 2 1 +
10 uF

4. Your circuit should like one of these.
Quick Check
Your circuit should like one of these.

5. Do the Experiment
Once you have the circuit complete, attach the battery.
You should notice the LED flash. Record your observations.
Try changing one or more of the resistors. Do not change the 220 Ohm resistor it is used to protect the LED. Record your observations.
Try changing the capacitor. Record your observations.
Troubleshooting:
If the LED does not flash, check to make sure everything is in correctly.
Check the battery. Does it have voltage?
Are there any breaks in the circuit?
Is the capacitor in correctly?
Is it wired correctly?
Check to make sure you have the 555 timer in the right way.

6. In complete sentences, write what you learned about a 555 timer .
Observations:
What did you learn?
In complete sentences, write what you learned about a 555 timer .