Lamp dimmer using NE555

4 years ago 3358
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Description

Lamp dimmer using NE555. This project is about simple lamp dimmer project using NE555 timer IC. PWM method is used for controlling the brightness of the lamp. This method is very power efficient and low cost compared to linear power control circuits. In PWM method the load is driven using a high frequency square wave and the duty cycle of this square wave is varied for controlling the power delivered to the load. The efficiency of this circuit was found to be 95.5% when tested in the lab. The same circuit can be also used to control the speed of DC motors. Working of the circuit. This circuit is basically an astable multivibrator with variable duty cycle using NE555 timer IC. The frequency is determined by using the equation F=1/(0.69(R1+2R2+R3)C1). With the components used, the base frequency of the circuit is 2.75KHz. The duty cycle and hence the brightness of the lamp can be controlled by varying the POT R3. Capacitor C2 by-passes the lower half of the POT R3 when timing capacitor C1 is charged. The base frequency will be constant irrespective of the position of R3 and the duty cycle only changes.

Capacitor C2 is meant for noise shunting. MOSFET IRF540 is used for switching the lamp according to the PWM output from the timer IC. The PWM output is connected to the gate of the MOSFET using resistor R5. R4 is a pull-down resistor. The load, ie; the bulb is connected to the drain of the MOSFET. C3 is filter capacitor which smooths the switched PWM waveform across the load. D1 is a freewheeling diode. This diode is not needed for an incandescent lamp because it produces no back emf during switching. But it is included in the circuit as a precaution in case you use inductive loads like motors. You can also control the brightness of 12V LED strings using this circuit. What ever may be the load, one thing you have to keep in mind is that the load current must not exceed the current rating of the MOSFET. Here the current rating of IRF540 is around 22A. enter image description here

Documents

lamp dimmer

audio amplifier with tone control

BOM

ID Name Designator Footprint Quantity Manufacturer Part Manufacturer Supplier Supplier Part Price LCSC Assembly Mounted
1 555 U1 DIP08 1
2 1k R1,R3,R5 R3 3
3 50k R2 TRIM_POT_PTH 1
4 0.01uF C2,C1 C1 2
5 IRF540 M1 SOT23 1
6 10k R4 R3 1
7 BULB H1 IND2-N10 1
8 1N4001 D1,D2 DO35-7 2
9 470uF/25V C3 CP_8X13MM 1
10 TL071 U1,U2 NONE 2
11 100k R1,R2 R3 2
12 2.2k R3 R3 1
13 470n C1 C1 1
14 Audio IN J1 CONNECTOR_2P-2.54 1
15 100k R4,R9,R12 TRIM_POT_PTH 3
16 18k R5,R6 R3 2
17 4.7k R7,R8 R3 2
18 22n C2,C3 C1 2
19 4.7n C4,C5 C1 2
20 15k R10,R11 R3 2
21 10u C6,C11 CP_8X13MM 2
22 TDA2003H U3 TO 1
23 470u C7 CP_8X13MM 1
24 220R R13 R3 1
25 10R R14 R3 1
26 1n C8 C1 1
27 2200u C9 CP_8X13MM 1
28 100n C10 C1 1
29 1R R15 R3 1
30 8R SPK 1X02 1
31 100u C12 CP_8X13MM 1

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PWM controller.jpg
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