PWM DC motor controller with NE555 and darlington transistors

The circuit  of pwm dc motor controller with ne555 and darlington transistors

This is 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.
红包扫雷苹果下载地址 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.

红包扫雷苹果下载地址 we must use the high power variable resistors only, which always called “rheostat resistors”

The simple dimmer using 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.

红包扫雷苹果下载地址 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.

The circuit  of pwm dc motor controller with ne555 and darlington transistors

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.

红包扫雷苹果下载地址 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

红包扫雷苹果下载地址 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.

红包扫雷苹果下载地址 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.
红包扫雷苹果下载地址 – 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.

Actual size single sided pcb layout

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

Actual size single sided pcb layout

Figure 4 the components-layout

红包扫雷苹果下载地址 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
R1_________1M ____1/4 watts 5%
R2_________10K____1/4 watts 5%
R3_________47K____1/4 watts 5%
R4_________2.2K____1/4 watts 5%
VR1________4.7M (preset) Trimpot
C1, C2______0.01uF 50V___Ceramic capacitors
C3, C4______2.2uF 50V__NP
L1_________150 uH ___inductor

Note: You can buy here:

Stepper Motor Generator Diagram

Stepper motors are a
subject that keeps recurring. This little circuit changes a clock signal
(from a square wave generator) into signals with a 90-degree phase
difference, which are required to drive the stepper motor windings. The
price we pay for the simplicity is that the frequency is reduced by a
factor of four. This isn’t really a problem, since we just have to
increase the input frequency to compensate. The timing diagram clearly
shows that the counter outputs of the 4017 are combined using inverting
OR gates to produce two square waves with a phase difference. This
creates the correct sequence for powering the windings: the first
winding is negative and the second positive, both windings are negative,
the first winding is positive and the second negative, and finally both
windings are positive.

Stepper Motor Generator Circuit

Stepper Motor Generator Circuit Diagram

Internally, the 4017 has a divide-by-10 counter followed by a
decoder. Output ‘0’ is active (logic one) as long as the internal
counter is at zero. At the next positive edge of the clock signal the
counter increments to 1 and output ‘1’ becomes active. This continues
until output ‘4’ becomes a logic one. This signal is connected to the
reset input, which immediately resets the counter to the ‘zero’ state.
If you were to use an oscilloscope to look at this output, you would
have to set it up very precisely before you would be able to see this
pulse; that’s how short it is. The output of an OR gate can only supply
several mA, which is obviously much too little to drive a stepper motor
directly. A suitable driver circuit, which goes between the generator
and stepper motor.

Rolling Shutter Motor Control

An electrically operated
rolling shutter usually has a standard control panel with a
three-position switch: up, down and stop. If you would like to automate
the opening and closing with a time controlled switch, a few additional
wires will have to be connected. Typically, the controls are implemented
as indicated in the schematic ‘Normal Situation’. If this is indeed the
case, then you can see in ‘New Situation’ how the shutter can be
automated with a timer. There is only one method to determine the actual
schematic of your control circuit, and that is to open the control box
and using an ohmmeter, pencil and paper to check out and draw the
circuit. Make sure you turn the power off first though! Connect a 230-V
relay (with both the contacts and the coil rated 230 VAC红包扫雷苹果下载地址) to the timer.


Circuit diagram

The changeover switch between automatic and manual control needs to be rated 230 VAC
as well and may not be a hazard for the user. The relay and switch are
preferably fitted in a plastic mains adapter enclosure with built-in
plug, which is plugged into the timer. It is a good idea to check first
if this will actually fit. Because of the manual/automatic-switch, the
operation is completely fail-safe and misunderstandings are out of the
question. The switch prevents the issue of conflicting commands (with
disastrous consequences) when, for example, the shutter is being
automatically raised and manually lowered at the same time.


Circuit diagram

Maximite Stepper Motor Interface

This simple circuit and program listing allows the Maximite microcomputer (SILICON CHIP,
March-May 2011) to control a stepper motor. It could be expanded to
allow for the control of multiple motors, with four of the Maximite’s
external I/O pins used to control each motor with identical driver
circuits. A ULN2003 Darlington transistor array (IC1) switches current
through the stepper motor’s two windings in either direction. When one
of the four Maximite output pins (8, 12, 16 & 20, corresponding to
I/Os 19, 17, 15 & 13) goes high, the corresponding output pin on IC1
goes low, sinking current through a motor winding. Conversely, when
these pins are high, the corresponding Darlington transistor is off and
红包扫雷苹果下载地址 so no current flows through that portion of the winding.


Circuit diagram

The centre tap of each motor winding is connected to a current source comprising PNP
Darlington transistor Q1 and some resistors. The maximum current is
determined by the resistive divider driving its high-impedance base,
setting the base voltage to around 9.1V when it is fully on. By adding
Q1’s base-emitter voltage (1.4V at 0.5A, as per the data sheet) we can
determine that there will be around 1.5V across the 3.3O resistor (12V –
10.5V), resulting in a current of 1.5V ÷ 3.3O = ~450mA. Transistor Q1
must be fitted with a medium-sized flag heatsink (Jaycar HH8504,
Altronics H0637) or larger to handle its maximum dissipation of (10.5V –
4.9V) x 450mA = 2.5W.

When one of the Darlington transistors switches off and current flow
through the corresponding motor winding ceases, the inductive winding
generates a back-EMF current which causes the voltage across that winding to spike. IC1 has internal “free-wheeling” diodes from each output to the COM pin, which is connected to the +12V supply. The back-EMF
current flows back into the power supply and the voltage spikes are
clamped at about 12.7V, so that the Darlington transistors do not suffer
红包扫雷苹果下载地址 collector reverse breakdown, which might damage them.

A 470µF capacitor provides supply bypassing for the motor while a
47kO pull-up resistor and toggle switch/pushbutton S1 drives input pin 9
of the Maximite, allowing manual control of the motor direction. Table 1
shows the sequence in which the output pins are driven to turn the
motor forward; the steps are run backwards for reverse operation. The
delay between the steps determines the speed at which the motor rotates.
The source code of the sample program is available for download from
the SILICON CHIP红包扫雷苹果下载地址 website (maximite_stepper_motor.bas).

PWM Dimmer/Motor Speed Controller

This is yet another
project born of necessity. It’s a simple circuit, but does exactly what
it’s designed to do – dim LED lights or control the speed of 12V DC motors. The circuit uses PWM to regulate the effective or average current through the LED
array, 12V incandescent lamp (such as a car headlight bulb) or DC
motor. The only difference between the two modes of operation is the
addition of a power diode for motor speed control, although a small
diode should be used for dimmers too, in case long leads are used which
will create an inductive back EMF when the MOSFET switches off.

Photo of Completed PWM Dimmer/Speed Control

Photo of Completed PWM Dimmer/Speed Control

The photo shows what a completed board looks like. Dimensions are 53
× 37mm, so it’s possible to install it into quite small spaces. The
parts used are readily available, and many subsitiutions are available
for both the MOSFET and power diode (the
latter is only needed for motor speed control). The opamps should not be
substituted, because the ones used were chosen for low power and their
ability to swing the output to the negative supply rail.

Note that if used as a motor speed controller, there is no feedback,
so motor speed will change with load. For many applications where DC
motors are used, constant speed regardless of load is not needed or
desirable, but it is up to you to decide if this will suit your needs.


Note that if used as a motor speed controller, there is no feedback,
so motor speed will change with load. For many applications where DC
motors are used, constant speed regardless of load is not needed or
desirable, but it is up to you to decide if this will suit your needs.

PWM Waveform Generation

PWM Waveform Generation

Figure 2 shows how the PWM principle
works. The red trace is the triangle wave reference voltage, and the
green trace is the voltage from the pot. When the input voltage is
greater than the reference voltage, the MOSFET
turns on, and current flows in the load. Because the frequency is
relatively high (about 600Hz), we don’t see any flicker from the LEDs, but the tone is audible from a motor that’s PWM controlled. The PWM
signal is shown in blue. The average current through the load is
determined by the ratio of on-time to off-time, and when both are equal,
the average current is exactly half of that which would be drawn with

Dimmer/Speed Controller Schematic

Dimmer/Speed Controller Schematic

The circuit is shown in Figure e. U1 is the oscillator, and
generates a triangular waveform. R4 and R5 simply set a half voltage
reference, so the opamps can function around a 6V centre voltage. U2A is
an amplifier, and its output is a 10V peak to peak triangle wave that
is used by the comparator based on U2B. This circuit compares the
voltage from the pot with the triangle wave. If the input voltage is at
zero, the comparator’s output remains low, and the MOSFET红包扫雷苹果下载地址 is off. This is the zero setting.

In reality, the reference triangle waveform is from a minimum of
about 1.5V to a maximum of 9.5V, so there is a small section at each end
of the pot’s rotation where nothing happens. This is normal and
practical, since we want a well defined off and maximum setting. Because
of this range, for lighting applications, an industry standard 0-10V DC
control signal can be used to set the light level. C-BUS红包扫雷苹果下载地址 (as well as many other home automation systems) can provide 0-10V modules that can control the dimmer.

While a 1N4004 diode is shown for D2, this is only suitable if the
unit is used as a dimmer. For motor speed control, a high-current fast
recovery diode is needed, such as a HFA15TB60PBF ultra-fast HEXFRED
diode. There are many possibilities for the diode, so you can use
whatever is readily available that has suitable ratings. The diode
should be rated for at least half the full load current of the motor,
and the HFA15TB60PBF suggested is good for 15A continuous, so is fine
with motors drawing up to 30A.


While it’s certainly possible to build the dimmer on veroboard or
similar, it’s rather fiddly to make and mistakes are easily made. Also,
be aware that because of the current the circuit can handle, you will
need to use thick wires to reinforce some of the thin tracks. This is
even necessary for the PCB version. Naturally, I recommend the PCB, and this is available from ESP. The board is small – 53 × 37mm, and it carries everything, including the screw terminals. The PCB is double-sided with plated-through holes, and has solder masks on both sides.

The MOSFET will need a heatsink unless you are using the dimmer for light loads only. It is necessary to insulate the MOSFET from the heatsink in most cases, since the case of the transistor is the drain (PWM
output). For use at high current and possible high temperatures, the
heatsink may need to be larger than expected. Although the MOSFET should normally only dissipate about 2W or so at 10A, it will dissipate a lot more if it’s allowed to get hot. Switching MOSFETs will cheerfully go into thermal runaway and self destruct if they have inadequate heatsinking. You may also use an IGBT
(insulated gate bipolar transistor) – most should have the same
pinouts, and they do not suffer from the same thermal runaway problem as

As noted above, there are many different MOSFETs (or IGBTs) and fast diodes that are usable. The IRF540 MOSFET
is a good choice, and being rated 27A it has a generous safety margin.
There are many others that are equally suitable – in fact any switching MOSFET rated at 10A or more, and with a maximum voltage of more than 20V is quite ok.


Connect to a suitable 12V power supply. When powering up for the
first time, use a 100 ohm “safety” resisor in series with the positive
supply to limit the current if you have made a mistake in the wiring.
The total current drain is about 2.5mA with the pot fully off, rising to
12.5mA when fully on. Most of this current is in the LED, which is also fed from the PWM supply so you can see that everything is working without having to connect a load.

Make sure that the pot is fully anti-clockwise (minimum), and apply
power. You should measure no more than 0.25V across the safety resistor,
rising to 1.25V with the pot at maximum. If satisfactory, remove the
safety resistor and install a load. High intensity LED
strip lights can draw up to ~1.5A each, and this dimmer should be able
to drive up to 10 of them, depending on the capabilities of the power
supply and the size of the heatsink for the MOSFET.


Bipolar Stepper Motor Control

First, we want to
explain how such a controller works and what’s involved. A bipolar motor
has two windings, and thus four leads. Each winding can carry a
positive current, a negative current or no current. This is indicated in
Table 1 by a ‘+’, a ‘–‘ or a blank. A binary counter (IC1) receives
clock pulses, in response to which it counts up or down (corresponding
to the motor turning to the left or the right). The counter increments
on the positive edge of the pulse applied to the clock input if the
up/down input is at the supply level, and it decrements if the up/down
红包扫雷苹果下载地址 input is at earth level.

The state of the counter is decoded to produce the conditions listed
in Table 2. Since it must be possible to reverse the direction of the
current in the winding, each winding must be wired into a bridge
circuit. This means that four transistors must be driven for each
winding. Only diagonally opposed transistors may be switched on at any
given time, since otherwise short circuits would occur. At first glance,
Table 2 appears incorrect, since there seem to always be four active
intervals. However, you should consider that a current flows only when a
and c are both active. The proper signals are generated by the logic
circuitry, and each winding can be driven by a bridge circuit consisting
of four BC517 transistors.

Two bridge circuits are needed, one for each winding. The
disadvantage of this arrangement is that there is a large voltage drop
across the upper transistors in particular (which are Darlingtons in
this case). This means that there is not much voltage left for the
winding, especially with a 5-V supply. It is thus better to use a
different type of bridge circuit, with PNP
transistors in the upper arms. This of course means that the drive
signals for the upper transistors must be reversed. We thus need an
inverted signal in place of 1a. Fortunately, this is available in the
form of 1d.

The same situation applies to 1b (1c), 2a (2d) and 2b (2c). In this
case, IC4 is not necessary. Stepper motors are often made to work with
12V. The logic ICs can handle voltages up to 15 to 18 V, so that using a
supply voltage of 12 V or a bit higher will not cause any problems.
With a supply voltage at this level, the losses in the bridge circuits
are also not as significant. However, you should increase the resistor
values (to 22 kΩ, for example). You should preferably use the same power
supply for the motor and the controller logic. This is because all
branches of the bridge circuit will conduct at the same time in the
absence of control signals, which yields short-circuits.

Two Basic Motor Speed Controllers

Here are two simple 12V
DC motor speed controllers that can be built for just a few dollars.
They exploit the fact that the rotational speed of a DC motor is
directly proportional to the mean value of its supply voltage. The first
circuit shows how variable voltage speed control can be obtained via a
potentiometer (VR1) and compound emitter follower (Q1 & Q2). With
this arrangement, the motor’s DC voltage can be varied from 0V to about
12V. This type of circuit gives good speed control and self-regulation
at medium to high speeds but very poor low-speed control and slow
starts. The second circuit uses a switchmode technique to vary motor

A very simple motor speed controller based on a compound emitter follower (Q1 & Q2)

a very simple motor speed controller based on a compound emitter follower (Q1 & Q2).

Here a quad NOR gate (IC1) acts as a 50Hz
astable multivibrator that generates a rectangular output. The
mark-space ratio of the rectangular waveform is fully variable from 20:1
to 1:20 via potentiometer VR1. The output from the multivibrator drives
the base of Q1, which in turn drives Q2 and the motor. The motor’s mean
supply voltage (integrated over a 50Hz period) is thus fully variable
with VR1 but is applied in the form of high-energy “pulses” with peak
values of about 12V.

This slightly more complicated circuit gives better low speed control and higher torque

this slightly more complicated circuit gives better low speed control and higher torque.

This type of circuit gives excellent full-range speed control and
gives high motor torque, even at very low speeds. Its degree of speed
self-regulation is proportional to the mean value of the applied
voltage. Note that for most applications, the power transistor (Q2) in
红包扫雷苹果下载地址 both circuits will need to be mounted on an appropriate heatsink.

Stepper Motor Control

A simple, low-cost
hardwired step per motor control circuit that can be used in low-power
applications, such as moving toys etc is presented here. The circuit
comprises a 555 timer IC configured as an astable multivibrator with
approx. 1Hz frequency. The frequency is determined from the following

红包扫雷苹果下载地址frequency = 1/t = 1.45/(ra + 2rb)c where ra = rb = r2 = r3 = 4.7 kilo-ohm and c = c2 = 100 µf.

The output of timer is used as clock for two 7474 dual ‘D’
flip-flops (IC2 and IC3) configured as a ring counter. When power is
initially switched on, only the first flip-flop is set (i.e. Q output at
pin 5 of IC2 will be at logic ‘1’) and the other three flip-flops are
reset (i.e. their Q outputs will be at logic ‘0’). On receipt of a clock
pulse, the logic ‘1’ output of the first flip-flop gets shifted to the
second flip-flop (pin 9 of IC2). Thus with every clock pulse, the logic
‘1’ output keeps shifting in a ring fashion. Q outputs of all the four
flip-flops are amplified by Darlington transistor arrays inside ULN2003
(IC4) and connected to the stepper motor windings marked ‘A’ through ‘D’
in the figure.

The common point of the winding is connected to +12V DC supply,
which is also connected to pin 9 of ULN2003. The colour code used for
the windings is shown in the figure. When the power is switched on, the
control signal connected to SET pin of the first flip-flop and CLR
pins of the other three flip-flops goes active ‘low’ (because of the
power-on-reset circuit formed by R1-C1 combination) to set the first
flip-flop and reset the remaining three flip-flops. On reset, Q1 of IC2
goes ‘high’ while all other Q outputs go ‘low’. External reset can be
activated by pressing the reset switch. By pressing the reset switch,
you can stop the stepper motor. On releasing the reset switch, the
红包扫雷苹果下载地址 stepper motor again starts moving further in the same direction.

Infrared Toy Car Motor Controller

This add-on circuit
enables remote switching on/off of battery-operated toy cars with the
help of a TV/video remote control handset operating at 30–40 kHz. When
the circuit is energised from a 6V battery, the decade counter CD4017
(IC2), which is configured as a toggle flip-flop, is immediately reset
by the power-on-reset combination of capacitor C3 and resistor R6. LED1
connected to pin 3 (Q0) of IC2 via resistor R5 glows to indicate the
standby condition. In standby condition, data output pin of the
integrated infrared receiver/demodulator (SFH505A or TSOP1738) is at a
红包扫雷苹果下载地址 high level (about 5 volts) and transistor T1 is ‘off’ (reverse biased).


Circuit diagram

The monostable wired around IC1 is inactive in this condition. When
any key on the remote control handset is depressed, the output of the IR
receiver momentarily transits through low state and transistor T1
conducts. As a result, the monostable is triggered and a short pulse is
applied to the clock input (pin 14) of IC2, which takes Q1 output (pin
2) of IC2 high to switch on motor driver transistor T2 via base bias
resistor R7 and the motor starts rotating continuously (car starts
running). Resistor R8 limits the starting current. When any key on the
handset is depressed again, the monostable is retriggered to reset
decade counter IC2 and the motor is switched off.

Standby LED1 glows again. This circuit can be easily fabricated on a
general-purpose printed board. After construction, enclose it inside
the toy car and connect the supply wires to the battery of the toy car
with right polarity. Rewire the DC motor connections and fix the IR
receiver module in a suitable location, for example, behind the front
glass, and connect its wires to the circuit board using a short 3-core
ribbon cable/shielded wire. Note. Since the circuit uses modulated
infrared beam for control function, ambient light reflections will not
affect the circuit operation. However, fluorescent tubelights with
electronic ballasts and CFL lamps may cause malfunctioning of the circuit.

Motor Speed Control

This circuit will allow
you to control the speed of an AC motor, for example an electric drill.
The way that this circuit works is as follows. The bridge rectifier
produces dc voltage from the 120vac line. A portion on this current
passes through the 10K ohm pot. The circuit comprised of the 10k pot,
the two 100 ohm resistors and the 50uf capacitors delivers gate drive of
the SCR. The diode D1 protects the circuit from reverse voltage spikes. The ratings of the bridge rectifier and the SCR should be 25 amps and PIV 600 volts. The diode D1 should be rated for 2 amps with PIV of 600 volts. The circuit can handle a load up to 10 amps. The SCR红包扫雷苹果下载地址 should be very well heat sinked.

Motor Speed Control

Motor Speed Control