Simple PWM Controller on NE555

With the analog integrated timer SE555 / NE555 (КР1006), produced by Signetics Corporation since the distant 1971, most of the Soviet and foreign radio amateurs are perfectly familiar. It is difficult to list for what purposes only this inexpensive, but multifunctional microcircuit was not used for almost half a century of its existence. However, even in spite of the rapid development of the electronics industry in recent years, it still continues to be popular and is available in significant volumes. The simple scheme of a PWM regulator offered by Jericho Uno is not a professional, fully developed development, distinguished by its safety and reliability. This is just a small cheap experiment, assembled on affordable budget details and fully satisfying the minimum requirements. Therefore, its developer does not take responsibility for all that can happen to your equipment when operating a simulated circuit.

PWM Controller Circuit on the NE555

Simple PWM Controller for NE555
To create a PWM device you will need:
  • soldering iron;
  • NE555 chip;
  • 100kΩ variable resistor;
  • 47 Ohm resistors and 1KΩ by 0.5W
  • >
  • 0.1 μF capacitor;
  • two 1N4148 diodes (KD522B).

Step-by-Step Assembly of the Analog Circuit

Building a circuit starting with the installation of jumpers on the chip. Using the soldering iron, we close the following timer contacts between each other: 2 and 6, 4 and 8.
Simple PWM regulator on NE555
Then, guided by the direction of the movement of electrons, we unsolder the shoulders of the diode bridge (current flow in one direction) on a variable resistor. The ratings of the diodes are selected from the available, inexpensive. You can replace them with any others - it practically does not affect the operation of the scheme. Simple PWM regulator on NE555 In order to avoid short circuits and burnout of the microcircuit when unscrewing the variable resistor to the extreme position, set the power supply shunt resistance to 1 kΩ (contacts 7-8).
Simple PWM controller on NE555
Since the NE555 acts as a saw generator, to get a circuit with a given frequency, pulse duration and pause,It remains to choose a resistor and a capacitor. An inaudible 18 kHz will give us a 4.7 nF capacitor, but such a small value of capacitance will cause the shoulders to skew when the chip is operating. We set the optimum to 0.1 microfarad (contacts 1-2).
Simple PWM regulator on NE555
Avoiding the opposite "squeaking" of the circuit and pulling the output to a high level can be something low-resistance, for example, a 47-51 Ohm resistor.
Simple PWM controller on NE555
It remains to connect the power and load. The circuit is designed for the input voltage of the on-board network of the car 12V DC, but for a visual demonstration it will also completely start from the 9V battery. We connect it to the chip input, respecting the polarity (plus 8 legs, minus 1 legs).
Simple PWM controller on NE555
It remains to deal with the load. As can be seen from the graph, when the output resistor decreases to 6V, the saw at the exit (legs 1-3) remains, that is, the NE555 in this circuit and the saw generator and the comparator simultaneously. Your timer is in a-stable mode and has a lower fill factor.50%.
Simple PWM regulator on NE555
The module withstands 6-9 A pass-through DC, so that with minimal losses you can connect to it either an LED strip in the car or a low-power motor, which also smoke dispel and face in heat poured. Something like this:
Simple PWM controller on NE555
Simple PWM controller on NE555
Or like this:
Simple PWM controller on NE555
Simple PWM controller on NE555

Principle of operation of the PWM controller

The operation of the PWM controller is quite simple. The timer NE555 monitors the voltage on the capacitor C. When it is charged, until the maximum is reached (full charge), the internal transistor opens and a logical zero appears at the output. Next, the capacitance is discharged, which leads to the closure of the transistor and the arrival of the logical unit. When the capacity is completely discharged, the system switches and everything repeats. At the moment of charge, the current flows along one arm, and when discharging, it is different.With a variable resistor, we change the shoulder resistance ratio, automatically lowering or increasing the output voltage. There is a partial frequency deviation in the circuit, but it does not fall within the audible range.

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