Bistable mode, also called flip flop, 555 timers hold their output (pin 3) either high or low depending on which input, trigger (pin 2) or reset (pin 4 ) was last given a low signal.
- 555 timer monostable mode – One shot
- 555 timer astable multivibrator mode – Flashing LEDs
- 555 timer schmitt trigger logic inverter – NOT gate
Assortment of commonly used integrated circuits (IC). I made a lot of videos with them
White version of the oscilloscope that I use in many of my recent videos.
- Trigger pin (called set pin in this circuit) with a low signal sets the output high. Unless the reset pin also has a low signal, in which case output stays low.
- Reset pin sets the output low no matter what, as long as it is pressed. after it is released, the output stays low until there is a low signal to the trigger/set pin.
- Pull up resistors hold the set/reset inputs high (Vcc) until a direct connection to 0V is made. Don’t leave input pins floating, they will pick up weak electromagnetic signals that surround them.
- Output LED headed to ground lights up when the output is high. High output voltage is however close to the positive supply voltage that the 555 outputs.
- Output LED headed to the positive supply (Vcc, 5V, etc.) lights when the output is low. Low 555 output is almost connecting directly the 0V/negative supply rail voltage.
Power supply I use in my videos.
555 timer bistable flip flop mode basic circuit with alternating LEDs electronics by electronzap