Many electronics circuits and projects for learning in simple ways.

PWM DC motor controller with NE555 and darlington transistors

This is 555 PWM dc motor controller circuit for dimmer a lamp or controll speed of a DC motor. I used to suggests these circuit by use principle most PWM (PWM Control Speed Motor 12V By TL494) form.
But TL494 is not cheap and hard to buy we use NE555 beter very cheap and popular.

This circuit have a lot of useful such as the DC dimmer , DC motor controller, etc.
Which can use up to 20 watts.

The working principle of circuit

A simple DC dimmer circuit that we see commonly, always use a variable resistors is adjuster voltage to load high-low as we need.

We must use the high power variable resistors only, which always called “rheostat resistors”


Figure 1 The simple dimmer using rheostat resistors

But disadvantage of circuits that use it, is very expensive and some power consumption in heat form, therefore, this way so low performance.

Then, we found best way that cheaper and high performance. By briefly provide a output voltage with very high frequencies.

This dimmer with on/off time range of wavefrom to load, Not cause a loss of energy in the form of heat anymore.

For really application circuit as show in Figure 2 will see that IC1-NE555 will acts as frequency generator for feed to the transistor output. Which serves as switch cut off voltage to a lamp.

Figure 2 the circuit diagram of PWM DC motor controller with NE555 and darlington transistors

The frequency value of circuit will depends on value of R3, R2, VR2 and capacitor-C1. Which time on/off, that will depends on adjusting of VR2.

For the value that can adjust time rang on : off up to 100 : 1 . Which will be provided to the load voltage nearly 100%, that is the bulb will fully light. Or if the motor will speed fastest, as well.

In the event that need to dimmer light, we can adjust on : off range up to 1 : 20

The output from pin 3 of IC1 will be fed through R4 to base TR1, making TR1 turn on-off the voltage to lamp as look of input signal.

The working of transistors as above will cause the voltage,to drop across between emitter – collector during 0.7V – 1V, and This was a loss of power to some part. But it very least when compare with the old circuit that use the rheostat resistors.

– The Diode-D1 acts as booster of time range on : off wide up.
– The potentiometer-VR1 acts as the adjuster the output voltage lowest as you want.
– The capacitor-C3, C4 and L1 acts as reducing the noise signal from the circuit don’t interfere with other electrical circuits.
– For L1, we can do it with We can make up your own using wire No. 20 SWG winding on ferrite cores for about 50 times.

How to builds

We can assemble the parts on the PCB as shown in Figures 3 Positioning device based circuits correctly. As Figure 4 For the output transistor that tall , need to hold on larger-size heat-sink.

Figure 3 the Actual-size,Single-sided PCB layout

Figure 4 the components-layout

When assemble the components as done circuit, then adjust VR2 until the lamp a few glow up softly, next adjust until go out lowest light, and later adjust VR1 again to really low light.

The components list.
IC1_NE555N _Timer IC
D1_1N4148_75V 150mA Diodes
0.25W, 5% Resistors
VR1_4.7M (preset) Trimpot
C1, C2_0.01uF 50V_Ceramic
C3, C4_2.2uF 50V_NP
L1_150 uH _inductor

Spot Lamp DC dimmer circuit using LM555-TIP2955

This is simple low voltage DC Dimmer Circuit. It can adjust the brightness of a maximum 12V 100W Power Spot Lamp from 5% to 95%.

In circuit use IC-555 as free-running multivibrator to drive both power PNP transistor,  to control the lamp with PWM mode.  And, using a few other components. Which easily buy in most of the local markets.
Working of the circuit

Spot Lamp DC dimmer circuit using LM555-TIP2955
Spot Lamp DC dimmer circuit using LM555-TIP2955

In the circuit, we use IC-LM555 is free-running Astable Multivibrator mode. Which these components R2, R3, VR1, D1, D2, and C1 determine the frequency output pin 3.

Then, the circuit can change the duty Cycle by adjusting VR1-potentiometer and R3. They also control a brightness level as you want.

Next, the output oscillator will limit load current, the lamp ON and OFF at a rate duty cycle of the multivibrator.

After that, the current flows to the base of Q1-TIP2955 and Q2-MJ2955 to drive the load.

We should install Q1, Q2 with the suitable heat sink. When the circuit operates in full power. The Q2 is too heat. It may damage.

The D3-general silicon diode protects a oscillator feedback. Which it can damage this circuit.

For a load of this circuit, you can use 10A 12V, power all lamps, or the strip lights LED, or high power LEDs.

The LED1 is a power on display. The R1-series resistor to limit current in save value for LED1.

‘Keep reading: 555 Pulse Generator circuits’ »

Parts you will need
IC1 = IC-555 Standard Timer Single 8-Pin Plastic Dip, Quantity: 1
Q1 = TIP2955 15 A, 60 V PNP Bipolar Power Transistor, Quantity: 1
Q2 = MJ2955 15 A, 60 V PNP Bipolar Power Transistor, Quantity: 1
D1,D2 = 1N4148 75V 150mA Diodes, Quantity: 2
D3 = 1N4002 100V 1A Diodes, Quantity: 1
LED1 = Red LED
R1 = 560 ohms 0.25W Resistors, Quantity: 1
R2 = 1K 0.25W Resistors,Quantity: 1
R3 = 1K-100K 0.25W Resistors,Quantity: 1
R4,R5 = 680 ohms 0.25W Resistors,Quantity: 1
VR1 = 100K Potentiometer, Quantity: 1
C1 = 0.027uF 50V Ceramic Capacitor,Quantity: 1

In addition, you can see other circuits. That also use for all power LAMP.

‘Keep reading: 12V-24 PWM motor controller’ »

This Post Has 13 Comments

  1. #Spot Lamp DC dimmer circuit using LM555-TIP2955

    A limiting resistor(>47Ω) in the collector of T1 must be employed. Otherwise, soon Q1 and probably Q2 will be history.

  2. Hi
    That Is a Vary Good Circuit.Thankyou

  3. Realy you are fantastic website that i see to now

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    thank you.
    your web are very good.

  5. Hi,م.مصطفى المصرى
    Thanks for your feedback.

  6. Hey I appliciated much the diagrams helps me much can I have more for how to make free power using altarnator and more about radiant power.

    #Spot Lamp DC dimmer circuit using LM555-TIP2955

  7. pls. how can i order parts

  8. I need variable Capacitor 1-100 µf or executive the enclosed circuit

  9. I wonder, the circuit should handle 100W load (9A) and the V+ is connected with an 1A fuse. How come??

    #Spot Lamp DC dimmer circuit using LM555-TIP2955

    1. Hello, Alexander Sergeyev
      Yes, It may be wrong. You should the fuse rating follow load current.

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