unsure about circuitry to combine switch, dc motor, potentiometer and led

seamus.c

Joined Feb 15, 2017
3
Hi, I am a little unsure about the correct circuity connecting a switch to turn on a dc motor which I would like to control the speed of with a potentiometer. When the motor turns on I would like to turn on an led also.

I was thinking of using a double pole double throw switch. I plan to connect the potentiometer in series with the motor as shown below (fig 1.) on one output terminal, say circuit A and turn on an led on a different output terminal but connected to circuit A.

Fig 1.

I was thinking of something similar to the diagram shown below in fig 2.

Circuit A: Motor in series with potentiometer, also on circuit A but a different terminal turn led on.

Fig 2.

When the switch is pressed the other way I would like the the circuit to power off, I am not sure what to do for this part or if I am correct in what I plan to do in the other part of the circuitry. Any assistant would be greatly appreciated. Thank you.

Joined Jul 18, 2013
19,176
A variable resistor is not a very efficient way, also it is really only suitable for constant loads, if the load varies so will the rpm.
Max.

seamus.c

Joined Feb 15, 2017
3
Although it may not be very efficient, in this experiment is it possible to use only a variable resistor to control motor speed with satisfactory results without the use of other components provided I have selected an appropriate resistor value for the type of setup in this circuit?

#12

Joined Nov 30, 2010
18,159
provided I have selected an appropriate resistor value for the type of setup in this circuit?
yes.
The problem is that selecting the value depends so much on the current the motor usually uses. This requires math, and you have not given enough numbers for anybody to provide any practical values.

seamus.c

Joined Feb 15, 2017
3
My apologies I plan to use a dc motor with the following specifications:

Nominal Voltage 9V
Current rating 2.85A
power rating 21.2W
output speed 13360 RPM

With regard to the circuit and interfacing the components together would you be able to offer any advice or observations on the proposed set up again many thanks.

Seamus