Monostable mode 555 timer, also called one shot, holds the output low until forced high. The output stays high for a period of time and then goes back to low. It is called monostable because low is the one stable condition.
- Output (pin 3) stays low (off/0V) until it is forced high/on (close to supply voltage). While the output is low, the LED in this circuit will be off because the other side of the LED is also at 0V (ground).
- Low signal to trigger (pin 2) sets the output high while a capacitor charges (see next bullet point). The LED is on while the output is high, because the output voltage is as close to the positive supply voltage as it can get.
- Capacitor connected to threshold (pin 6) and discharge (pin 7) starts charging through a resistor while the output is high.
- Output stays high until threshold/discharge capacitor reaches 2/3 of the supply voltage. Then the output goes low and the capacitor instantly discharges through pin 7 (discharge pin). Both stay that way (that why they are stable) until the next low pulse to pin 2.
White version of the oscilloscope that I use in many of my recent videos.
Power supply I use in my videos.
- 555 Timer IC The particulars of this integrated circuit covered on this page make a lot more sense after you study the basic circuits that follow.
- 555 timer bistable mode – Flip flip basic circuit
- 555 timer monostable mode – One shot
- 555 timer astable multivibrator mode – Flashing LEDs
- 555 timer schmitt trigger logic inverter – NOT gate
- 555 timer LDR controlled astable multivibrator mode LED flasher circuit
- 555 timer – Buzzer output – Astable multivibrator mode – Light dependent resistor LDR controlled circuit
- Electronic component appearance and schematics – Commonly used through hole versions
- Electronic circuit basics
- Voltage sources for electronics basics
- Multimeter measuring voltage
- Resistor component – Learning electronics resistors
- Light Emitting Diodes – Indicator LEDs
- LED circuit -Lighting a Light Emitting Diode
- Resistor limiting current – Ohms law
- Multimeter measuring current
- Wattage – Electrical Power unit
- Resistors connected in parallel
- Series resistors
- Voltage divider – Setting a fractional voltage
- Resistor color code
- Diode – Rectifier
- Trimpot – Trimmer potentiometer – Voltage divider – Variable resistor
- Capacitor component
- Capacitor RC time constant
- Voltage ramp Demonstrated using a capacitor.
- LM334 three terminal adjustable current source not a common component. I use for an easy current source in many circuits.
- Switch NOT logic gate – digital signal inverter
- Switch OR gate – LED circuit
- Switch AND gate – LED circuit
- Switch based NAND logic gate – LED demonstration circuit
Transistors will probably be the most challenging components to learn. Understanding them will help you understand all of electronics much better, and help you the most in being creative while designing your own circuits.
- NPN BJT switch circuit – Bipolar Junction Transistor – 2N3904
- PNP BJT switch – Bipolar Junction Transistor – 2N3906
- NPN BJT emitter follower circuit – transferring a voltage minus a diode drop
- PNP BJT emitter follower circuit – Transferring weak signal voltage with a diode voltage shift
- Bipolar Junction Transistor BJT voltage follower circuit improved to eliminate base emitter diode shift
- NPN BJT current source – Bipolar Junction Transistor – 2N3904
- PNP BJT current source – Bipolar Junction Transistor – 2N3906
- Schmitt trigger – NPN BJT
- Zener diode component – voltage reference – regulator
- Voltage doubler circuit fragment- Capacitor charge pump – Some V loss
- 7805 5V positive voltage regulator IC
- Battery voltage state of charge SOC – From fully charged to discharged
These pages are still being compiled.