The 555 timer is the most well known IC (integrated circuit) in electronics. It is useful in many circuits. There’s a number of ways to control the output, which can be either high or low. It all depends on the signals (voltage in relationship to power supply voltage) that you give to the set, threshold, and the reset pins. It’s best to learn their roles by building circuits from schematic presented to you by others.
Pages covering the 3 basic 555 timer circuits:
- Brief 555 bistable mode flip flop alternating LEDs circuit
- Brief 555 timer monostable one shot mode circuit
- Brief 555 timer astable multivibrator mode circuit
- Brief 555 Schmitt trigger logic inverter
- Brief light dependent resistor LDR controlled astable multivibrator mode 555 timer circuit
- Brief passive buzzer controlled by 555 timer astable multivibrator set by light dependent resistor LDR circuit
Most, if not all, of my 555 timers are the NE555 timer with 8 through hole pin DIP (Dual inline package). They are easy to insert in to a prototype breadboard. The following numbers are taken from the Fairchild Semiconductor LM555/NE555/SE555 datasheet. As always, verify all information by checking datasheets.
- Supply voltage (Vcc): Min 4.5V – Max 16V
- Max power dissipation (Pd): 600mW
Pin layout below, starting top left and working counter clockwise.
- 1 – GND
- 2 – Trigger
- 3 – Output
- 4 – Reset
- 5 – Control voltage
- 6 – Threshold
- 7 – Discharge
- 8 – Vcc
As an Amazon Associate I earn from qualifying purchases
When buying or using a 555 timer, or any other component for that matter, it is best to consult it’s datasheet, or other written documentation of it’s use and limitations. This skill takes a while to learn but is very rewarding once you get good. So, practice looking up datasheets! A Google search of the part name or number, such as “555 timer datasheet”, will usually get you to a number of datasheets. Try to find the specific part and manufacturer for your component.
As an Amazon Associate I earn from qualifying purchases.