Troubleshooting a 555 Timer

The 555 timer circuit is often simple to troubleshoot.

The 555 timer integrated circuit, first made in the 1970s and still available today, has been a favorite of electronics designers. Troubleshooting 555 timer circuits is largely a matter of checking for bad connections and possibly replacing the timer itself.

Power

As with any circuit, a 555 timer needs a dependable DC power supply to work properly, in this case between 4.5 and 16 volts. You can test the supply's voltage with a digital multimeter.

Connections

A quick examination of the circuit in which the 555 timer is being used may reveal broken wires, bad solder joints or similar problems that could interrupt the flow of current.

Components

A 555 timer circuit uses a few capacitors and resistors. Burn marks, cracks and bulges indicate damaged components. If you see any parts that have suffered physical damage, replace them.

Timer Chip

Most of the active elements in a 555 timer circuit are on the IC chip itself. You can purchase a 555 for a dollar or less, so if the other circuit parts appear good, it's easiest to simply replace the 555 IC.

References

• Williamson Labs: 555 Timer Tutorials

Resources

• National Semiconductor: 555 Timer