How to use 555 to make a full range dimmer / speed controller

This is a quick summary of how to make a dimmer using 555. The 555 Timer IC used is NE555P from TI.

Design-1

The design below has a minimum of 50% duty cycle and maximum of 100% duty cycle. It's capable of making the attached device performing at its peak (100% duty cycle, but it's unable to turn off the device completely (the device will still operate at 50% of its peak performance even when the potentiometer is turned all the way to the end).

Design-2

The design below can do 0 ~ 100% duty cycle.

For a chip that was designed back in 1970 ~ 1971 (I was around 1-year old at that time), this is truly an amazing chip. I salute you Hans R. Camenzind.

Put the circuit to work

Below are the videos showing the waveform and the running of the motor. One of the motor has 0.1uF capacitor across the positive and the negative terminal of the motor, and the other one doesn't.

DC 12V Brush Gear Motor PWM Speed Control - w. 0.1uF Cap.

DC 12V Brush Gear Motor PWM Speed Control - w/o 0.1uF Cap.

Note,

When the above design is used to drive motor via MOSFET, it's better to have the PWM frequency in the range of 10KHz (C TRI = 1nF), than 1KHz (C TRI = 10nF). See below scope screen shot for the difference.

The 1KHz operating range is within human audible frequency range. The noise may be annoy to some people.

References

LEDs, 555s, PWM, Flashers, and Light Chasers Index <-- Very good. Must read!!
http://forum.allaboutcircuits.com/blog/leds-555s-pwm-flashers-and-light-chasers-index.378/

Full range PWM (555)
http://forum.allaboutcircuits.com/threads/full-range-pwm-555.31324/

**555 on 24v Circuit**
http://www.555-timer-circuits.com/555-on-24v.html

**LM317 / LM338 Voltage Calculator** <- Very Useful!!
http://www.reuk.co.uk/LM317-Voltage-Calculator.htm

Simplest Method to Make a Motor Turn Off, Turn On, Go Forwards, and Go Backwards
http://www.robotroom.com/DPDT-Bidirectional-Motor-Switch.html

H Bridge Motor Speed Controller Tutorial
https://www.youtube.com/watch?v=iYafyPZ15g8

How to use 555 Timer to make a 50% Duty Cycle Astable Oscillator

This is a quick summary of how to use 555 Timer to make a 50% Duty Cycle Astable Oscillator.

50% Duty Cycle Astable Oscillator

The above 555 oscillator produces a 50% duty cycle as the timing capacitor, C1 is charging and discharging through the same resistor, R2. When the output from the 555 oscillator is HIGH, the capacitor charges up through R2 and when the output is LOW, it discharges through R2. Resistor R1 is used to ensure that the capacitor charges up fully to the same value as the supply voltage.

The formula for calculating the output frequency at pin 3 is as follow.

Below is the frequency range of the above design using the above formula.

The waveform of pin 3 when R2 is around 96K Ohm. It's about 0.5Hz.

References:

555 Oscillator Tutorial <-- Very Good!!
http://www.electronics-tutorials.ws/waveforms/555_oscillator.html

Pulse Generator circuits using IC-555
http://www.eleccircuit.com/simple-pulse-generator-circuit-by-ic-555/

Variable frequency generator using a 555 timer chip
http://www.edaboard.com/thread262276.html

Unit Converter

Farad ↔ Microfarad Conversion
http://www.endmemo.com/sconvert/fuf.php

Unit Juggler
https://www.unitjuggler.com/convert-frequency-from-s(p)-to-Hz.html?val=1.6