Industrial Controller - {PH_0} {PH_1} in stock ler at Northern Industrial Homemade Circuit Projects Get free circuit help 2. i 5 Simple DC Motor Speed Controller Circuits Explained Last Updated on May 16, 2023 by Swagatam (https://www.homemade- circuits.com/author/swag/) Acircuit which enables a user to linearly control the speed of a connected motor by rotating an attached potentiometer is called a motor speed controller circuit. Industrial Controller {PH_0} {PH_1) in stock 5 easy to build speed controller circuits for DC motors are presented here, first one using MOSFET IRF540, second one using IC 555, the third concept with IC 4093, fourth design involves the IC 741, while the fifth design utilizes IC 556, featuringController Avery cool and easy DC motor speed controller circuit could be build using a just a single mosfet, a resistor, and a pot, as shown below: a ) 540 12V DC Input homema » ae MOTOR |= preset’ DC Motor Caution: Electrical experiments can be dangerous! By using this site you acknowledge that you are aware of this fact and want to proceed at your own risk! Using a BJT Emitter Follower 470 ohm + Swatt TransistorMotor 1N4007 As can be seen the mosfet is rigged as a source follower or a common drain mode, to learn more about this configuration you may refer to this post (https:/www,homemade-circuits.com/emitter-follower-transistor-application-circuits/), which discusses a BJT version, nevertheless the working principle remains the same. In the above DC motor controller design, the pot adjustment creates a varying potential difference across the gate of the mosfet, and the source pin of the mosfet simply follows the value of this potential difference and adjusts the voltage across the motor accordingly. It implies that the source will be always 4 or 5V lagging behind the gate voltage and vary up/down with this difference, presenting a varying voltage between 2V and 7V across the motor. When the gate voltage is around 7V, the source pin will supply the minimum 2V to the motor causing a very slow spin on the motor, and 7V will be available across the source pin when the pot adjustment generates the full 12V across the gate of the mosfet. Here we can clearly see that the mosfet source pin seems to be "following" the gateTyQSIEL THUSL De always aroun OV, IH ULUer lO @laie ine HOsiet wo GUNUUEL Oputiiaty. Anyway, the above configuration helps to enforce a smooth speed control on the motor, and the design could be built quite cheaply. ABAJT could be also used in place of the mosfet, and in fact a BJT would produce a higher control range of about 1V to 12V across the motor. Video Demo Simple DC Motor Speed Control using a Single Mos... When it comes to controlling motor speed uniformly and efficiently, a PWM based controller becomes the ideal option, here we will learn more, regarding a simple circuit to implement this operation. DxUsing MOSFET as a High Power Potentiometer The next figure below shows a very simple DC motor speed controller circuit that employs a MOSFET as a high-power potentiometer (rheostat). The circuit is designed to work with 12 volt DC motors having a peak current usage of below 5 amp. The mains AC supply is provided through the on/off switch S1 to the primary winding of the isolation and step-down transformer T1. The push-pull rectifier circuit of D1 and D2 full-wave rectifies T1's output, and the resulting unfiltered DC output is smoothed to a certain extent by C1 to produce a relatively constant DC potential. Sta on/cff 7. 74 Fst At D3 =aThere can be a significant level of ripple on this DC output, however it is unimportant in this application. Tr1 provides power to the load and is biased through a resistive divider circuit consisting of R1, VR1, and R2. The gate bias voltage provided to Tr1 might not be adequate to allow the MOSFET to conduct meaningfully with the wiper of VR1 at the R2 end of its rotation, and the motor will not operate. Advancing the wiper of VR1 towards the opposite end of its rotation allows a constantly increasing bias to be supplied to Tr1, resulting in a steadily decreasing drain to source resistance. Because of this, the power delivered to the motor rises in tandem with the motor's speed, until Tr1 reaches saturation (where the motor runs at its full speed). VR1 may therefore be used to change the motor's speed from minimum to maximum speed.being reduced to zero. D3 is a safety diode that inhibits any excessive reverse voltage spikes that may occur as a result of the motor's excessively inductive load. Design#2: PWM DC Motor Control with IC 555 The design of a simple motor speed controller using PWM may be understood as follows: Initially when the circuit is powered, the trigger pin is in a logic low position since the capacitor C1 is not charged. The above conditions initiates the oscillation cycle, making the output change to a logic high. Ahigh output now forces the capacitor to charge via D2.The moment pin #6 triggers, pin #3 and pin #7 reverts to logic low. With pin #3 at low, C1 yet again begins discharging via D1, and when the voltage across C1 falls below the level that's 1/3 of the supply voltage, pin #3 and pin #7 again become high, causing the cycle to follow and go on repeating. It is interesting to note that, C1 has two discretely set paths for the process of charging and discharging via the diodes D1, D2 and through the resistance arms set by the pot respectively. It means the sum of the resistances encountered by C1 while charging and discharging remains the same no matter how the pot is set, therefore the wavelength of the out put pulse always remains the same. However, since the charging or the discharging time periods depends upon the resistance value encountered in their paths, the pot discretely sets the these time periods as per the its adjustments. Since the charge and discharge time periods is directly connected with the output duty cycle, it varies according to the adjustment of the pot, giving form to the intended varying PWM pulses at the output.The average result of the mark/space ratio gives rise to the PWM output which in turn controls the DC speed of the motor. The PWM pulses are fed to the gate of a mosfet which reacts and controls the connected motor current in response to the setting of the pot. The current level through the motor decides it speed and thus implements the controlling effect via the pot. The frequency of the output from the IC may be calculated with the formula: F = 1.44(VR1°C1) The mosfet can be selected as per the requirement or the load current. The circuit diagram of the proposed DC motor speed controller can be seen below: MOTOR 0 |= Ao mosfet (https://www.homemade-circuits.com/wp- content/uploads/2012/05/PWMmotorcontrolcircuit.png), Prototype Image: 0Video Testing Proof: Testing a PWM Motor Controller CircuitIn the above video clip we can see how the IC 555 based design is used for controlling speed of a DC motor. As you may witness, although the bulb works perfectly in response to the PWMs and varies its intensity from minimum glow to maximum low, the motor does not. The motor initially does not respond to the narrow PWMs, rather starts with a jerk after the PWMs are adjusted to significantly higher pulse widths. This does not mean the circuit has problems, it is because the DC motor armature is held between a pair of magnets tightly. To initiate a start the armature has to jump its rotation across the two poles of the magnet which cannot happen with a slow and gentle movement. It has to initiate with a thrust. That's exactly why the motor initially requires a higher adjustments for the PWM and once the rotation is initiated the armature gains some kinetic energy and now achieving slower speed becomes feasible through narrower PWMs. However still, getting the rotation to a barely moving slow status can be impossible because of the same reason as explained above.mm C! —_ 0.0047uF Having said this, the motor could show a better control at the slower levels if the motor is attached or strapped with a load through gears or pulley system. This may happen because the load will act as a damper and help to provide a controlled movement during the slower speed adjustments. Dx Industrial Controller {PH AVIPH 1Vin ctackAnother Simple PWM DC Motor Controller Circuit memade-Fircuits.com Design#3: DC Motor Controller with Multiple Features The following DC motor controller circuit provides multiple control features such as: * PWM Speed Control. « Direct Speed Without PWM Speed Control (with slow Initialization). « Forward/Reverse. * Sudden Brake.— ToMOTOR When Switch A is pressed, the PWM function kicks in and the motor speed can be regulated by moving the potentiometer P1. Pressing Switch B ON or OFF causes the motor to change direction between anticlockwise and clockwise motions. Meaning this switch B can be used to enable reverse/forward motion on the motor. Discover related topics De Motor >ve motor apeeo Comror a De Motor Controller 150a De Motor Controll Dc Motor Controller Regardless of the Switch A position, if Switch C is pressed, causes the motor to attain a direct full speed. In this position the PWM function does not work. If Switch A and Switch C are both open, then the motor will remain switched OFF. Design#4: Using a Single Op amp The op amp circuit described below can be used for regulating the speed and direction of a motor. It functions as a voltage follower, with its positive input (pin #3) linked to potentiometer R3, which functions as a dual-purpose controller for motor speed and direction. At the mid-point of the potentiometer's range, the op amp output is close to zero, causing neither Q1 nor Q2 to conduct current. Moving the potentiometer wiper towards the positive side will make the op amp output become positive, allowing Q1 to conduct current to the motor and increase its speed. +9V RI 1KAdjusting the potentiometer towards the negative supply will cause the op amp output to swing to a negative voltage, resulting in Q2 turning on while Q1 is turned off. This action reverses the motor's rotation direction. Industrial Controller {PH_0} {PH_1) in stock Buy new refurbished Siemens Industrial Controller at Northern Industrial Depending on the rotation direction, the motor's speed increases as the potentiometer wiper is pulled towards either end of its range. To determine the maximum acceptable DC voltage range for the selected motor, it may be necessary to monitor the voltageControl Varying.a DC motor velocity (https://www,.homemade-circuits,com/high-current-motor- control-using-arduino/) may appear to be not so difficult and you may find plenty of circuits for it. However these circuits do not guarantee consistent torque levels at lower motor speeds, making the functioning quite inefficient. Moreover at very low speeds due to insufficient torque, the motor tends to stall. Another serious drawback is that, there’s no motor reversal feature included with these circuits. The proposed circuit is completely free from the above shortcomings and is able to generate and sustain high torque levels even at lowest possible speeds. Circuit Operation Before we discuss the proposed PWM motor controller circuit, we would also want to learn the simpler alternative which is not so efficient. Nonetheless, it may be considered reasonably good as long as the load over the motor is not high, and as long as the speed is not reduced to minimum levels. The figure shows how a single 556 IC can be employed for controlling speed of a connected motor, we won't go into the details, the only notable drawback of this configuration is that the torque is directly proportional to the speed of the motor.{PH_O} {PH_1} in stock ial Contr Coming back to the proposed high torque speed controller circuit design, here we have used two 555 ICs instead of one or rather a single IC 556 that contains two 555 ICs in one package. Circuit DiagramMain Features Briefly the proposed DC motor controller (https://www.homemade- circuits.com/2015/07/motor-sneed-and-time-controller-circuit html) includes thea The torque is never affected by the speed levels and remains constant even at minimum speed levels. The motor rotation can be flipped or reversed within a fraction of second. The speed is variable in both the directions of the motor rotation. The two 555 ICs (https://www.homemade-circuits. com/search/label/IC%20555) are assigned with two separate functions. One sections is configures as an astable multivibrator generating 100 Hz square wave clocks which is fed to the preceding 555 section inside the package. The above frequency is responsible for determining the frequency of the PWM. Industrial Controller {PH AVIPH Vin ctackThe transistor BC 557 is used as a constant current source which keeps the adjoining capacitor at its collector arm charged. This develops a saw-tooth voltage across the above capacitor, which is compared inside the 556 IC with the sample voltage applied externally over over the shown pin- out. The sample voltage applies externally can be derived from a simple 0-12V variable voltage power supply circuit. This varying voltage applied to the 556 IC is used to vary the PWM of the pulses at the output and which eventually is used for the speed regulation of the connected motor. The switch S1 is used to instantly reverse the motor direction whenever required. Parts List + R1, R2, R6 = 1K, + R3 = 150K, « R4, R5 = 150 Ohms, * R7, R8, R9, R10 = 470 Ohms, © C1=0.1uF,“ 73,74 =TIP127 T5 = BCS5S57, T6, T7 = BC547, D1---D4 = 1N5408, Z1 = 4V7 400mw IC1 = 556, S1 = SPDT toggle switch The above circuit was inspired from the following motor driver circuit which was published long back in elecktor electronic India magazine. Controlling Motor Torque using IC 555 N1toNd = IC 4049 The first motor control diagram can be much simplified by using a DPDT switch for the motor reversal operation, and by using an emitter follower transistor for the speed control implementation, as shown below:Rt Improved Torque at Low Speed using CMOS PWM Control Althaninh the single MASEFT linaar matar enead eantrailar lavarite avnlainad at theoptimum speed. This may be certainly not a serious issue however, and just requires the installing of a moderately large heatsink on the MOSFET. Industrial Controller {PH_O} {PH_1} in stock F at Northern Industrial Amuch more critical concern is that the motor is likely to stall as soon as this kind of linear controller is adjusted for any lower speeds. This is because the MOSFET in this situation has a relatively high resistance, which offers the supply input with a significantly high output impedance. When the load on the motor is increased, it attempts to draw excessive amounts of supply current, but this leads to a larger voltage drop across the transistor and a lower supply voltage across the motor. As a result, the power delivered to the motor does not vary significantly, rather it decreases. Due to this, the motor has a propensity to stall. Also, there is an opposite reaction in which lowering the load on the motor cuts its current drain, resulting in a greater supply voltage and a significant rise in motor speed.A Improved Torque using CMOS PWM Speed Control One method of implementing this, and the one employed here, is to have a circuit that provides a fixed output pulse duration while altering the frequency of the pulses to modify the motor speed. A low frequency produces long gaps between pulses and feeds a relatively low power to the motor. When the frequency is increased, there are no noticeable gaps between the pulses, and the motor receives a nearly constant signal. This results in a high average power in the motor, which runs at full speed. The benefit of this system is that when the motor is being pulsed, it is essentially getting the full power during the ON periods of the pulses, and is free to consume a large supply current if the load on the motor actually demands it. As a result, the motor is powered by a sequence of strong pulses that defy stalling and provide improved torque even at reduced speeds. The following figure depicts the circuit diagram of a pulsed DC motor speed control. Here, T1, D1, D2, and C1 derive a sufficient DC supply from the mains AC supply. Tr1 is hooked up in series with the motor, but its gate terminal receives the output signal from an astable multivibrator circuit (https://www,.homemade-circuits,com/cmos- astable-bistable-monostable-circuits-explained/).This pwm circuit is built using two of the four gates of a CMOS 4001 device, which are utilized ina CMOS astable setup that is quite a conventional design. Industrial Controller {PH AVIPH 1Vin ctacke. Acouple of timing resistors can be seen connected between the output of gate 1 and the junction of R1 and C2, which differs from the conventional PWM design. VR1 and R2 are the two resistors, along with guiding diodes D3 and D4 connected in series with the output of NAND gate 1. The two diodes ensure that R2 works like the timing resistance whenever the astable's output is high, and VR1 functions as the timing resistance whenever the output is low. The period of the output pulses is constant since R2 has a predetermined value. The interval between them could be changed by varying VR1. This will be nearly zero when it is adjusted for lowest resistance. The output mark space ratio is greater than ten to one at maximum resistance. VR1, therefore, could be adjusted to generate the desired motor speed with effective torque, with the lowest speed happening at full resistance and the highest speed occurring at zero resistance. Precision Motor Control using a Single Op Amp An extremely refined or intricate control of a d.c. motor could be achieved making use of an op-amp and a tacho-generator. The op-amp is rigged as a voltage sensitiveA Switching action of the op amp would happen in just a couple of millivolts around the reference voltage. You will need a dual power supply, which may be just zener stabilizedThis motor controller enables infinitely adjustable range without involving any form of mechanical hassles. The op amp output is only +/- 10% of the supply rails level, thus employing a double emitter follower huge motor speeds could be controlled.The reference voltage could be fixed through thermistors, or an LDR etc. The experimental set up indicated in the circuit diagram made use of an RCA 3047A op amp, and a 0.25W 6V motor as tacho-generator which generated around 4V at 13000 r.p.m for the intended feedback. Additional Circuit Designs: PWM Motor Control using Only BJTs The following circuit also uses PWM principle for the desired motor speed control, however, it does not depend on any integrated circuits or ICs, rather uses only ordinary BJTs for the implementation. | got this from an old magazine page.Motor Control Circuits using LM3524 The IC LM3524 is a specialized PWM controller circuit which allows us to configure very useful and precision motor speed control circuits as explained below:The above diagram shows a basic PWM motor control circuit using the IC LM3524. The design additionally incorporates a sensor based feedback control through the IC LM2907 (https://www.homemade-circuits.com/frequency-to-voltage-converter-circuit/). Asmall magnet is attached with the motor shaft, such that during the rotations, the magnet goes past closely to an iron core pickup coil transformer. The mechanism, causes the rotating magnet to induce a sharp electrical pulse in the pickup coil, whichThe feedback system ensures that the speed of the once set can never deviate trom the set point, providing a precise control of the speed. The pot at pin#2 of the LM3524 is used for controlling the speed of the motor. Sensorless Control, Without Motor Back EMF The next LM3525 PWM speed control design allows the feedback control without incorporating a complex tachometer mechanism, or cumbersome sensor arrangements as implemented in the previous design.Here, the back EMF from the motor is utilized as the feedback signal and applied to the input of the IC LF198. In case the speed tends to rise beyond the set level, the LF198 compares the rising EMF signal with the sample reference signal from the LM393 output. The resulting output is sent to the error amplifier of the IC LM3524 for the necessary processing of the output PWM to the driver transistors. The controlled PWM due to this sensor-less feedback through the back EMF ultimately enables the motor to remain precisely fixed at a correct speed, as adjusted by the pin#2 potentiometer.cifsuits.com/borewell-motor-pump-starter-controller/) 2. How to Make a 3 Phase VED Circuit (https://www.homemade-circuits.com/3- phase-vfd-circuit/) 3. Operating a DC Motor Clockwise/Anticlockwise with a Single Switch (https://www.homemade-circuits com/operating-dc-motor-clockwiseanticlockwi/) 4. Material Storage Level Controller Circuit (https://www.homemade- circuits.com/material-storage-level-controller/), 5. BLDC Ceiling Fan Circuit for Power Saving _(https://www.homemade- circuits.com/bldc-ceiling-fan-circuit-for-power/), 6. Simple Tea Coffee Vending Machine Circuit (https:/Awww.homemade- circuits,com/simple-tea-coffee-wending-machine/) About Swagatam | am an electronic engineer (diplETE ), hobbyist, inventor, schematic/PCB designer, manufacturer. | am also the founder of the website: https:/Avww.homemade-circuits.com/, where | love sharing my innovative circuit ideas and tutorials. Ifyou have any circuit related query, you may interact through comments, Il be most happy to help!Have Questions? Please Comment below to Solve your Queries! Comments must be Related to the above Topic!! © Subscribe ~ Join the discussion 337 COMMENTS Newest » Rabia Ali © 5days ago hello! a project is given to me that says “Design and implement the power electronics kit that provides the variable speed of the motors. The old motor had the power ratina, voltage. and currenta @ Last edited 5 days ago by Rabia Ali Reply Swagatam © Scaysago Reply to Rabia Ali Hello, A triac based speed controller is usually preferred for controlling AC motor speed, which can keep the motor speed at a constant level. However if the input voltage varies then the speed might also vary. | do not have a circuit to ensure a constant current and constant voltage to the motor if the input AG varies Reply Rabia Ali © 3 ¢ays.ago Reply to Swagatam 0 do you have a triac based speed controller's circuit? if yes please send me or refer me to a reference link, Reply tor Swagatam © 3¢aysago 2 Reply to Rabia Ali Yes, you can try one of the circuits explained in the following article Reply Sapan bhavsar © 11 days ago Hello, I need circuit diagram of Closed loop control system for blde motor with hall effect sensor for the prototype purpose only for my college submission please provide me circuit diagram with specific ‘components rating marksa Reply to Sapan bhavsar Hi, please search “BLDC” using the search box at the top, you may find some good options. Reply Ronnie Lau © montage Ihave started a new way to slot car racings. | am running 540 motors on slot car tracks that power by DC 12-14V. The problem is that the 540 motor burns up the hand controller. Can you help by advising me what to change on the hand controller like by replacing the resistors or thickening the wires etc. Or better yet is there a better design to build a new controller. 540 motor | was told can go up to 200-300W and draws 20-40 amps. Thank you for your help. Sincerely, Ronnie Reply Aubor Swagatam © 1 month ago © Reply to Ronnie Lau 1f 300 W 40 amp is burning the controller then no doubt you will have to upgrade the wires. appropriately and also upgrade everything through which this current flows. Reply Ronnie Lau © 1 month ago Q Reply to Swagatam Can you kindly point out what size of resistor to start then what size of capacitor? 14 AGW wiring should work if not 12 definitely will do. Thanks a Million, Ronnie Reply Swagatam © 1 month agoUr 2mvo siuu be Yume EHUUYIH TUF Ue WwiteD, Reply Prabakaran © 2months ago We need a simple closed loop control of de motor circuit for demonstration for students. please guide me to get a circuit. Reply Author Swagatam © 2 months ago Q Reply to Prabakaran Closed loop will require a feedback control loop through the motor’s back EMF which looks a jcult concept, | do not have it at this moment. Reply Ged © 3months ago Trying to find a circuit similar to that shown for the LM3524 (Back EMF (Whearstone bridge?) speed monitoring, PWM) that also has variable slew-rate limiter. So the truning the speed control fully-up all at once does not result in motor jerking into like, simliarly trune speed control from max to stop does not result in motor jarring to a halt Reply ‘sbor Swagatam © mons ag9 &Q Reply to Ged Sorry, presently | do not have this circuit with me, if| happen to find one, will surely let you know. Reply Ged © months age Q Reply to Swagatam Thank you, | can find circuits that contain 2 of the 3 elements (PWM, ‘Feedback’, variable slew-rate limiter) but never all 3A Q Reply to Gea Yes | understand, | hope someone on this forum might be able to help! Reply Shiv © 4monts ago I'm trying to make a suitable speed control circuit for a 24v 15a motor which I'm using for a diy drill also as electric screwdriver. Kindly suggest a good and efficient circuit for it with forward and reverse function Using 775 bearing motor Reply thor Swagatam © 4 mons ago & Reply to Shiv I will recommend you the following circuit. For 15 amp operation you can replace the shown, mosfet with a IRF3205. https://www.homemade-circuits.com/wp-content/uploads/2022/05/DC-pwm-motor-control.jpg (htips:Jwww.homemade-cireuits,com/wp-content/uploads/2022/05/DC-pwm-mator-control jog) The forward reverse feature can be implemented with a DPDT switch or with a 4017 flip flop relay circuit Reply Theresa Sutton © 6 months ago ||am enjoying the artices and slowly leaming the principles. | am building an electric spinning wheel using a RS5SO DC motor . It will be powered by an AC 110 to 12v power supply and/or 12v battery pack, Maintaining smooth speed changes and constistent torque is required. Abilty to reverse rotation from a stop is also required. Do you a simple circuit that might fit this. Reply Swagatam © émonths agoa circult-with-reverse-forward-1200%474,jpg_(hitps://www,homemado-circults.comwp- content/uploads/2022/01/DC-motor-speed-controller-circuit-with-reverse-forward1-1200x474 jpg) Reply Steve Long © 9montns ago I need to buy a DC Motor Speed Controller for my golf trolley. The problem with most of them, or alll of them is that they have pots to control the speed. The pots keep wearing out. Therefore, | would like to have one that goes up and down in speed by the use of a rocker switch. What would that be called? Are they available? Reply Author Swagatam © mons ago &Q Reply to Steve Long understand that pots can wear out over time, however we don’t sell ready made kits from this site, Nevertheless I can design a circuit which can be used to regulate the motor speed using a push button. If possible | will ty to update the design soon as a new article Reply Ged © 3monins ag0 & Reply to Stove Long Hello Steve, do you have to have continuously variable speed or would a series of fixed speeds work? Iso the potentiometer could be replaced with a rotary selector switch (much more robust) wired- Uup with resistances for the fixed speeds. (The only way | can think that the rocker switch could work is to have something like an electronic version of the selector switch where the rocker ‘clicks’ the selector switch up or down a ‘notch’, ke the gear change on a Formula1 car!) Reply James © tt months age Hi, so | have a question about why all DC electric motor controllers on the market are as described above. They all either have variable speed control from very low speed to maximum speed or have 3 fixed speed settings. My question is, is it possible to build a circuit and program controller that allowstor Swagatam © 11 months ago Reply to James Hi, thanks, and glad you liked the article. The specifications that you have mentioned can be probably implemented using the following modified design Do let me know if you any further questions. Reply Kiwa © 8 montis ago Q Reply to Swagatam Can this circuit be used on 18v motor Reply utr Swagatam © & months ago © Reply to Kiwa Yes it can be used, but the 18V must be converted to 12V for supplying the ICs Replybeen reading and came to this design where you have ' vanabl3 speeds and this is pretty much what | was looking for, but I'm stil looking for one more add, not sure if will be possible or f this circuits already does it. My idea is a ride-on car for a kid that, as he grows up, | can easily change or swap a resistor and therefore increase the top speed, With the diagram you have here | understand I can get that,... Read more » Reply Author Swagatam © 6 months ago 2 Reply to Jose Thank you Jose, All the circuits above have a potentiometer for adjusting the motor speed. Can you please tell me which schematic are you referring to? | guess you are trying to have an option where the speed range can be adjusted through a fixed resistor selector and then have a facilty to adjust the speed from 0 to max within those fixed ranges. Yes this feature can be included in all of the above designs. I would recommend the following circuit which looks pretty easy to configure and use: control jpg (https://www homemade-circuits.com/wp-content/uploads/2022/05/DC-pwm= motor-control.jpg) Reply Jose © months age Q Reply to Swagatam Thanks. Sorry I forgot to paste an image of the circuil, but yes, | was talking about this one (https:/www.homemade-circuits. com/wp-contentluploads/2022/08/DC- motor-speed-controller-with-3-ranges jpg). As you said, my idea was to have a (or a serie) or fixed resistor and remove them from the circuit as the kid becomes older, so the top speed increases, thus the previous circuit could give me the 3 speed (low/medium/high) and the potentiometer to adjust the speed within any range. | have been trying this week to do something that | found on the internet but it didn't, work, couldn't control the speed with the potentiometer. | tested... Read more » ReplyGreat! yes that design should work. have improved it further so that only one pot is used, you can see it in the following image. All the best to you. Reply Jose © months ago Q Reply to Swagatam MAny thanks, I'l ty this one when | source the components. I'll try to remember to let you know how it goes Reply tor Swagatam © 6 months ago RQ Reply to Jose No problem. All the best to yout Reply Chaly © Smontrs ago Q Reply to Swagatam Is it possible to vary the the speeds with a single botton. If so can you please give me the circuit diagram. It will be highly appreciated.A ®Q Reply to Chaly It may be possible using an additional 4017 IC with the IC 555. However, the speed adjustment will be UP, UP, UP, then after 10 steps back to zero and then again UP, An upidown sequence at any desired point may not be possible. Reply Chaly © 4 monins ago Q Reply to Swagatam First of all thanks for the approval and reply. ! am stil interested in the use of a single botton to vary the speed of the motor. Can the use of a variable digital resistor in place of the switch be the answer? If so can you please give a circuit diagram. Thanks for all Reply Author Swagatam © 4monihs ago & Reply to Chaly Sure, that’s a good idea. | will ry to solve it for you, but first please find out which digital potentiometer can you procure for the implementation. Reply John © 11 months age Hi Swagatam, Thank you for your website! I have quite enjoyed it for a couple of years and I'm sure many people find it equally educational, informative and overall good read. I'm in need of a suitable speed control circuit. | will be making a mini drill press (for PCB's) with a 775 motor https://mantech.co.za/Productinfo.aspx?Item=82M0668 Because it's a drill | am considering torque for times | might be drilling something else at lower speeds. So was considering your designs: Improved Torque using CMOS PWM Speed Control and Design#3: Using IC 556 for Enhanced ‘Speed Control (Version 3). I'm limited by... Read more » ReplyThank you John! Glad you liked the website! Yes you can try the CMOS speed controller circuit, with a full bridge rectifier input. However please note that this circuit was taken from an old magazine which claims that circuit would provide high torque at lower speeds, | am myself Unable to confirm this theory, Yes FS1 is a fuse. Another think is that a 6 amp transformer will not be able to provide high torque to a 10 amp motor, so you may have to opt for a 10 to 15 amp transformer. The IRF540 can handle upto 20 amps... Read more » Reply