Introduction: LED Blinker and PWM Oscillator Using 555 Timer
Everyone has been beginner in electronics and for beginners sometimes it may be hard to build some functional circuits. Thats why i decided to post this kind of a project. This circuit is simplified version of a simple circuit which the schematics of it was given by the manufacturer of the 555 timer. Even tough this circuit is simple you wont believe the feeling of satisfaction when it works! This circuit is not useful alone but it may fulfill important roles for example as a PWM driver, Square wave generator, clock signal and so on in complex circuits! So lets get started!
Step 1: Components/Tools Needed
1x NE555 (Or any kind of 555 timer).
1x Timing Capacitor. Calculation procedure of the value will be explained later on. In my case i used a 10 uF electrolytic for LED blinking ,100 nF ceramic for using it as a oscillator.
1x Bypass capacitor of your choice. It is optional but it is highly recommended that you use it. In my case i used a 100 nF ceramic capacitor and it worked fine.
2x Timing resistors. You can use single potentiometer or a trimpot instead of using 2 resistors.
1x 220 Ohm Resistor. This one will be used for current limiting for the LED. you can calculate the resistor value yourself but 220 ohm will be fine in most cases.
1x LED. A LED of your favorite color
1x Breadboard for prototyping on it.
Some wires to connect the components on the breadboard.
A power supply or batteries to power up your circuit.
Step 2: Calculations and Assembly
The circuit schematic is given in the picture. The formula for output frequency is:
1.44/(R1+2R2).C = f
In this formula f stands for frequency, C stands for the timing capacitor, R1 stands for timing resistor 1, R2 stands for timing resistor 2.
The formula for output waveform duty cycle is :
You can calculate the values of the capacitor and resistors with these formulas according to your needs. Dont forget that if you use a pot its value will be total resistance, not the single resistors! The C2 on the schematic is a bypass capacitor so its not necessary. If you have problems about the circuit feel free to comment.
Step 3: HAVE FUN!
Now the best part! Playing around with it! If you want to use it with high power loads you can use this circuit with a transistor or MOSFET. this thing is so versatile that you can even make a function generator with this thing! this circuit can be used as logic circuit clock, oscillator, pwm generator and so on. If you have any problems with this design feel free to leave a comment. I hope you liked this instructable, if so please consider sharing this instructable to help me. Stay tuned for the next project: Easy FM RF Transmitter!
Question 1 day ago on Step 2
Is it possible to modify the circuit so that the connected LED fade down, but does not shut off completely before fading up again?