The circuit introduced right here can be utilized to control the velocity of fanatics using induction motor. The speed keep watch over is nonlinear, i.e. in steps. The present step quantity is displayed on a 7-segment display. Speed may also be different over a huge range since the circuit can alter the voltage utilized to the fan motor from 130V to 230V RMS in a most of seven steps. The triac used within the remaining stage is fired at totally different attitudes to get different voltage outputs by applying short-dura-tion current pulses at its gate. For this pur-pose a UJT relax-ation oscillator is used that outputs sawtooth waveform. This waveform is coupled to the gate of the triac thru an optocoupler (MOC3011) that has a triac driver output stage.
Pedestal voltage keep an eye fixed on is used for varying the firing angle of the triac. The power provide for the comfort oscillator is derived from the rectified mains by the use of 10-kilo-ohm, 10W series dropping/limit-ing resistor R2. The pedestal voltage is derived from the non-filtered DC thru optocoupler 4N33. The behaviorivity of the Darlington pair transistors inside this optocoupler is different for getting the pedestal voltage. For this, the sure sup-ply to the LED inside the optocoupler is attached via completely different values of resistors the use of a multiplexer (CD4051).
Circuitdiagram:
Digital Fan Regulator Circuit Diagram
The value of resistance selected through the multiplexer is determined via the keep watch over in-put from BCD up-/down-counter CD4510 (IC5), which, in flip, keep an eye ons ahead bi-asing of the transistor inside optocoupler 4N33. The comparable BCD outputs from IC5 are also linked to the BCD-to-7-seg-ment decoder to display the step quantity on a 7-segment display. NAND gates N3 and N4 are config-ured as an astable multivibrator to supply rectangular clock pulses for IC5, while NAND gates N1 and N2 generate the active-low rely let (CE) enter using either of push-to-on switches S1 or S2 for rely up or count down operation, respectively, of the BCD counter.
Optocoupler 4N33 electrically isolates the high-voltage section and the digital section and as a consequence prevents the user from shock hazard when the usage of switches S1 and S2. BCD-to-7-segment decoder CD4543 is used for riding each common-cathode and common-anode 7-segment shows. If phase enter pin 6 is ‘high’ the decoder works as a common-anode decoder, and if phase input pin 6 is ‘low’ it acts as a common-cathode decoder. Optocoupler 4N33 should habits reasonably even when the show is zero, i.e. pin 13 (X0, at ground level) is switched output pin three. To keep away from this problem, regulate preset VR1 as required the use of a plastic-handled screwdriver to get no output at zero studying in the display.
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