# Questions tagged [control]

Control refers to systems that control other systems, whether that be industrial machinery, lighting or devices used in a home

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### Switching DC with MOSFET: p-Channel or n-Channel; Low Side Load or High Side Load?

I think, it is time I understand working principle of MOSFET transistors... Suppose that; I want to switch voltage on a resistive load by a MOSFET transistor. Any control signal between -500V and +...
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### Stability problem in unity-gain opAmp

As a part of a controlled power supply for hardware-in-loop testing for a student driven project, I had to develop a current buffer (voltage follower) which could source up to 1 A. I had the (bad) ...
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### How do I find the second order transfer function from this step response diagram?

I have the following diagram of a system's step response: I'm having trouble understanding how to calculate the system's transfer function, given this diagram. Specifically, I don't understand how ...
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### Control differences between ac induction motor and brushless dc motor?

I have a fairly solid background in industrial AC motor control (soft starters, VFDs, etc.) but something that I'm certainly NOT well versed in is brushless DC motors... the type found in every hard ...
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### AC fan speed control

I use this fan to cool my room, but sometimes it is too fast and I have to frequenctly turn it on and off to keep normal temperature. Maybe it is possible to reduce the speed by connecting a resistor ...
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### over and critically damped systems settling time

I know that for second order systems the settling time(St) equation is: So my question is, should this same formula be used when the system is over or critically damped? Is it right to use it in that ...
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2k views

### Using 240v mains on/off as input to microcontroller

I have a light switch that switches 240v (UK) mains. Instead of using that to directly control a light, I want to use it as an input to a controller board so I can also automate the lighting. (It's ...
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### PID controller slowly oscillates out of control

I am trying to tune PID controllers for my drone. There are 3 controllers, one each for Pitch, Yaw and Roll. I have gotten Yaw tuned to a reasonable amount and I am assuming the values for Kp, Ki and ...
2k views

### Buck Converter Control Scheme- Why isn't just a comparator not enough?

I am supposed to come up with some control schemes for the converter before understanding the standard PWM control scheme. Isn't it just enough if the output of the converter is compared with a ...
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### How do I get a position from an encoder?

I have a motor that drives a rail which I need to know the position of. I have an AM102 encoder attached to the motor. But am unsure how to get a position from it. I have powered it up and attached ...
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### 220v AC Fan regulator

i need to regulate the speed of a noisy kitchen FAN from a microcontroller (arduino board), i have been looking around and checked a lot of websites and schematics, and i think the solution should ...
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2k views

### Effect of right half plane zero on bandwidth of control system

It is known that the right half zero and the delay limit the achievable bandwidth of a control system. Can someone please explain the reason, how the right half plane zero limits the achievable ...
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7k views

### Smallest Delay Possible in a RF Remote Control

I have a very basic knowledge on electronics but that's it. so I don't know this topic well. Altho, I'm able to assembly a circuit , check it and make it work. I've been searching for info about RF ...
3k views

### Please explain in layman's terms how a PID accounts for inertia in temperature control

I'm building my own hobbyist microprocessor-controlled reflow oven. I'm using (mechanical) relays to turn the heaters (i.e. quartz tubes) on or off. I've noticed heating lags a couple of seconds ...
1k views

### Digital SMPS Vs. Analog SMPS

There are several ways to implement the current/voltage control for an SMPS. The easy way I see is to use an ASIC/PMIC to manage the control loop. One of the other methods would be implement a PID ...
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### What potentiometer should I choose?

I want to create a sound amplifier with the LM386 and I need a potentiometer. I don't have a clue what I'm doing (:P) but I've printed out the datasheet (for the LM386) and had a look at it. So I ...
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This article gives 2 main disadvantages: Variable frequency Requires ESR on the output cap Is variable frequency a big of a deal? Why would synchronization matters for a converter? And why are high ...
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### Obtaining Poles and Zeros from frequency response

What is the process of obtaining the poles and zeros from frequency response plot or data. Any reference or Matlab code will be great help
9k views

### Using a motor to open doors

I have made a wooden case to hold both my Xbox 360 and my PS3. It's as wide as both consoles laid down next to each other and as high as the console. it has 2 doors on the front, one for each console. ...
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### Confusion in understanding control system?

I am learning basics of control systems from following link http://instrumentationandcontrollers.blogspot.com/2010/11/types-of-control-systems.html It says that automatic washing machine & ...
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243 views

### BIBO and impulsive stability in voltage-controlled electrical circuits

Branching from the comments here, TimWescott gave this example of an open-loop unstable electrical system: Find the nearest NPN power transistor. Put it in a circuit with a healthy (for it) voltage ...
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### System response types

Whenever I am given a system type with a certain transfer function, I am always asked to proceed to find out the 1. impulse response and 2. step response of the system. My question is, what is so ...
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### Is building a DC-DC PSU PWM controller from discrete components a terrible idea?

I am building a 1kW PSU that is controlled with DSP MCU. It requires a lot of features such as synchronous rectification, bidirectionality, current regulation. Those features make the PSU very exotic ...
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506 views

### Why is unity feedback used?

Why is the unity feedback system used? This block diagram is for a 2 DOF ball balancing using a PID controller.
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210 views

### digitaly controlled voltage divider for picky audio recording enthousiasts

I want to replace expansive multi-deck rotary switches with a micro-controller and digitally controlled (i2C or ISP) analog switches. It will be used in a vintage (1972) discreet transistor ...
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### How to go about determing the System Type of my setup?

I have a small project where I am PID tuning two servo motors. Something very similar to this: I am interested in finding the system type of the above setup, which includes the PID loop I have tuned. ...
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309 views

### Final transistor in VOX circuit design is saturated even when no audio is supplied

Background: I have a μBITx v6 HF transceiver. It has an audio input and output, and a mechanism where the transmitter is keyed up when the ring connector (called PTT, push-to-talk) from the audio ...
564 views

### Transistor current control with collector feedback [duplicate]

In my last question, Transistor current control with positive feedback differential amplifier I made a mistake. The actual circuit seems like this I am beginner in linear electronics and I am very ...
13k views

### What is the name of the protocol(s) used to let an automatic garage door opener know which button I've pushed on the wall control panel? [closed]

The wired wall control panel in my garage has only 2 wires connected to it. Yet somehow it acts different when I push the big "door" button than when I push the "light" button or the "lock" button. ...
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### How to tune a PID controller to a nonlinear process

I have a nonlinear thermal process (nonlinear radiation becomes more and more present as temperature goes up) that I would like to tune a PID controller to. I'd like to control the temperature as ...
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### Pole Zero Cancellation on a Root Locus

Problem Design a controller in the feed-forward path to minimize the effects of the two pairs of dominant poles. Use the pole-zero cancellation technique via the root locus diagram. I have a 5$^{th}$...
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### Temperature-Controlled Fan

How do I trigger a fans function after a setpoint temperature is reached? I want to avoid using a PID Controller, and my heating element will be external of the circuit. Once the fan cools the ...
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### Loop gain(s) for multi-loop circuits

With the aim to combine some good properties of two different opamp types we can make use of the composite amplifier principle (see the figure). For example, we could combine good (small) input offset ...
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### Modeling scalar control of PMSM

I have met with a scalar control algorithm for a permanent magnet synchronous motor. I haven´t heard about it before so I decided to develop a dynamic model to further analyze this control algorithm. ...
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### DALI : How commissioning process takes place in DALI system?

I have gone through various documents regarding the Commissioning in the DALI interface. But I finding it difficult to understand some of the points. So if anyone with DALI Commissioning can help me ...
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### buck converter in CRM

I would like to simulate the ZVS Synchronous rectification buck converter, I know if I operate in ZVS I need to change the switching frequency of the buck converter. Here are my questions: How to ...
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242 views

### Mistake in published paper about magnetic levitation?

As I was reading through this paper: Nonlinear Model & Controller Design for Magnetic Levitation System, I stumbled cross section 3.3 which I could not follow. Summarizing section 3.3 Non Linear ...
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### Analog implementation of imaginary roots in a transfer function

I have a simple boost converter, and from multiple papers I've read through, a Type 3 Compensator is recommended. I designed one in Matlab/Simulink, and it reacts very quickly. The problem is, when I ...
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### Voltage regulator vs. voltage controller

I frequently meet the references to voltage-regulators and voltage-controllers. However, looking at the specs I find them to perform the same function. Is there a difference between the two, or ...
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### Linear Regulator: MOSFET vs BJT

Currently I am doing a project on a voltage regulator. Can you tell me some advantages of MOSFETs over BJT? Apart from a higher power loss, I can not find much. In control engineering it is much more ...
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### Full bridge HVDC to modfied square sine - random half side MOSFET burn

I am trying to make a step-down 350V to 220V voltage converter. I decided to go with rather simple circuit of full bridge MOSFET inverter since my loads are only resistive or switched. I had built it ...
3k views

### Can a phase margin become bigger than 180° and is this bad?

I have a wrong mental model about phase margin in control theory. I see that a phase of -180° is bad. If my input is a sine wave and I have negative feedback, which has a -180° phase shift, the ...
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### Simple Implementation of BiSS C interface for a position encoder

The BiSS C DB3 protocol interface for Absolute encoder is an Open Source and Free Communication protocol hardware compatible with SSI interface. It is used widely in absolute position encoders. ...
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### MOSFET overheating in pwm control

I'm using a MOSFET to switch a 24V, 15A load, with the gate input being a 500Hz PWM signal. However, this is causing the MOSFET to overheat and blow. Any suggestions would be appreciated. R1 = 100 ...
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### What's the Laplace transfer function of a moving average?

What is the Laplace transfer function of a moving average? $$y_k=\frac{x_k+x_{k-1}+x_{k-2}+x_{k-3}+...+x_{k-N+1}}{N}$$ I tried to get it from the z-domain transfer function using conversion tables: \...
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### Difficulties in modelling magnetic levitation system?

I am currently working on and writing a project (not homework) surrounding magnetic levitation with an electromagnet having to levitate an object underneath itself. I have taken a look at relevant ...
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### DC Motor control Optocoupler

My current project does involve some DC motors which I have to control the speed of. I'm will probably use the PWM pins of my arduino mini for this. Currently I am building my first prototype of the ...
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### Switching / dimming a high power mains heater

I need to make an adjustable power controller for a 3kW heater that will run off single-phase 240V AC power. How should it be done? Maybe a triac circuit similar to that used for dimming lights. ...
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1 vote