KIT pulse width modulator DC > PWM , Velleman K8004
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Velleman je kompanija specijalizirana za elektroniku. Osnovana je 1975. godine u Belgiji. Velleman je renomirani proizvođač kit elektronike. Chipoteka vam nudi kablove, generatore funkcija, bušilice, prijemnike, kanalne predajnike, alarm simulatore, 3D pisače i pripadajuću dodatnu opremu marke Velleman.
This control circuit is ideal for the accurate control of DC motors, lighting levels, small heaters
as well as other applications.
The circuit converts a DC voltage into a series of pulses, such that the pulse duration is directly
proportional to the value of the DC voltage.
The great advantage of such a circuit is that almost no power is lost in the control circuit.
Protected against overload and short circuit.
Pulse-width modulation (PWM), or pulse-duration modulation (PDM) is a modulation technique that conforms the width of the pulse,
formally the pulse duration, based on a modulator signal information.
Although this modulation technique can be used to encode information for transmission, its main use is to allow the control of the power supplied to electrical devices, especially to inertial loads such as motors.
The average value of voltage (and current) fed to the load is controlled by turning the switch between supply and load on and off at a fast pace.
The longer the switch is on compared to the off periods, the higher the power supplied to the load is.
The PWM switching frequency has to be much faster than what would affect the load, which is to say the device that uses the power.
Typically switchings have to be done several times a minute in an electric stove, 120 Hz in a lamp dimmer, from few kilohertz (kHz)
to tens of kHz for a motor drive and well into the tens or hundreds of kHz in audio amplifiers and computer power supplies.
The term duty cycle describes the proportion of 'on' time to the regular interval or 'period' of time;
a low duty cycle corresponds to low power, because the power is off for most of the time.
Duty cycle is expressed in percent, 100% being fully on.
The main advantage of PWM is that power loss in the switching devices is very low.
When a switch is off there is practically no current, and when it is on, there is almost no voltage drop across the switch.
Power loss, being the product of voltage and current, is thus in both cases close to zero.
PWM also works well with digital controls, which, because of their on/off nature, can easily set the needed duty cycle.