# Tagged Questions

104 views

### Does the frequency of a PWM signal have to be constant for a DC motor/fan speed control?

All PWM control systems I have seen for DC motor/fan speed control used a constant frequency. Is this really necessary in all cases? How would the motor current have to be calculated for a PWM ...
129 views

### Speed control for high power DC brushed motor

I am going to drive and bi-directionally control the speed of some 12V/24V, 100W to 300W DC brushed motors. I have some experience in controlling small DC motors (6V/9V/12V, 0.5A to 2A) with PWM ...
305 views

### how to automatically reverse the direction of a stopped gear motor and restart 12 hours later

The reversible gear motor needs to turn on @ 6:00 am pull a object 12 inches and shut off. Twelve hours later the gear motor needs to turn on and reverse the direction and place the object back in ...
117 views

### How to syncronize two motors with one pot?

I am trying to synchronize two dc motors with their own controllers. The controllers are name brand and use a 10k pot to control the speed. I have a duel 10k pot and would like to be able to "trim" ...
199 views

### Choosing relay to operate water pump

Based on my research so far, I've concluded that a relatively low-cost, yet reasonably reliable way to control operation (on/off) a motorized water pump, is a well spec'd EM-relay with flyback diode. ...
155 views

### What is the mathematical relationship between MOSFET switching frequency (motor speed control) and motor speed in rpm?

What is the mathematical relationship between the switching frequency of MOSFET in a three phase motor controller (induction motor and BLDC motor) and the speed in rpm of the motor shaft?
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### MOSFET relay connections to control a 3V motor

I need to turn a 1A, 3V motor on and off with a touch switch. I bought Omron 653-G3VM-61-AR and quickly smoked it. I had the battery + connected thru a 300 Ohm resistor to the touch switch (to get ...
248 views

### Motor Soft Starter

I am demonstrating a soft-starter for a technical report, and I am having trouble finding the correct motor and power source. I want to use SCRs in a reverse-parallel configuration to limit the ...
615 views

### Can a motor driver for 5V be used for a 24V motor?

I’m controlling a 5V motor with Arduino but need more torque which means a more powerful motor. Here is my scheme. (I took it form a tutorial): Here Arduino is controlling a 5V unipolar stepper ...
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### What type of electric motor drive can be used for keeping a load at specific heights? [closed]

We are planning to adjust the level of a load (around 50 kg) by using an electrical motor. Now we are using a hand crank and we want to get rid of this manual process. For example we want to ...
4k views

### 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 ...
223 views

### Regulate DC-Pump throughput

Does anybody know whether it is possible to easily regulate the throughput of a DC water pump? E.g. one you would use for your pond or indoor fountain. I would like to avoid lowering the duty cycle ...
981 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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### Soft Starter Sizing for No Load Testing of Motors

Don't know if this would be more appropriate on any other stackexchange site but my question is : How do you evaluate the sizing of a softstarter for no-load testing of an induction motor ?? For ...
1k views

### What determines the speed of a brushless DC motor

When driving a brushless DC motor, which parameters control the speed. Is it the current in the windings, the voltage, or both? What determines the maximum speed? If you drive the windings with ...
2k views

### 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 ...