DC motor

R

Raul

Guest
First, let me say hello to everyone as I am new to the group. My
question is how can I wire a DC motor to be reversible. Can I use a
potentiometer? It's for a remote control fan. The switch will be
connected to a servo. What I want is: The more I turn to the right the
faster the fan goes clockwise. The more I turn to the left the faster
the fan goes counter clockwise.
If anyone can help that would be great.
Thanks, Raul
 
Raul <webmaster@2minclip.biz> wrote:
First, let me say hello to everyone as I am new to the group. My
question is how can I wire a DC motor to be reversible. Can I use a
potentiometer? It's for a remote control fan. The switch will be
connected to a servo. What I want is: The more I turn to the right the
faster the fan goes clockwise. The more I turn to the left the faster
the fan goes counter clockwise.
Click to expand...
Are you sure it's a simple DC motor?
Most small fans are not, and cannot be reversed.
 
"Raul" <webmaster@2minclip.biz> wrote in message
news:5902f39f.0412030833.6d9ca8d8@posting.google.com...
First, let me say hello to everyone as I am new to the group. My
question is how can I wire a DC motor to be reversible. Can I use a
potentiometer? It's for a remote control fan. The switch will be
connected to a servo. What I want is: The more I turn to the right the
faster the fan goes clockwise. The more I turn to the left the faster
the fan goes counter clockwise.
If anyone can help that would be great.
Thanks, Raul
Click to expand...
You didn't give any voltage or current ratings. If it is a low power DC
motor, I drew up something that would probably work for you. Check it out at
http://www.fncwired.com/MotorExample/
Brian
 
-"You didn't give any voltage or current ratings. If it is a low power
DC
motor, I drew up something that would probably work for you. Check it out at
http://www.fncwired.com/MotorExample/"
Click to expand...
I'm sorry, it's a small DC I bought at a shop. It's 6v. I might change
it to a 3v because physical space limitations. Thanks for the drawing,
I'll see if I can get it to work.

Raul
 
I'm also wondering about the parts in your dual powersource drawing.
You have a NPN and a PNP transistor. Will any do or do they need to be
specific?
What do I use for the amplifier? I apologize for my ignorance. I'm a
newbie who builds junkbots, if I don't have the part number, it's hard
for me. This is for a small underwater ROV. The motor will control the
verticle movement.
Raul
 
Yes, by switching the leads the motor will run either clockwise or
counter clockwise. So I guess I just need a switch to swap the
voltage. That's good. I can have the servo connected to the switch and
the speed control at the same time. That might be the easiest way.
Thanks, Raul
 
I got all the parts but it doesn't work yet. I'm sure it's some stupid
thing I'm doing wrong. Here is a shot of the bread board setup. What
do you think the problem is?

http://www.asianhound.com/motor.html

Thanks, Raul
p.s. I must add I can't believe how great the response has been for my
problem. If I could only get people that actually work for me to be
this enthusiatic about stuff.
 
On 4 Dec 2004 02:39:32 -0800, webmaster@2minclip.biz (Raul) wrote:

Yes, by switching the leads the motor will run either clockwise or
counter clockwise.
Click to expand...
that's your main problem solved. some motors only run one-way whatever
the polarity attached (automobile starter motors, for example).

So I guess I just need a switch to swap the
voltage. That's good. I can have the servo connected to the switch and
the speed control at the same time. That might be the easiest way.
Thanks, Raul
Click to expand...
you want a power mosfet in to drve the motor with a PWM signal; that's
most efficeint. there are some simple and really cheap circuits out
there that you can use. just do a search on the web.

--

Fat, sugar, salt, beer: the four essentials for a healthy diet.
 
Ok, I re-did the bread board but still no dice. Here are pics of the
current setup.

http://www.asianhound.com/motor.html

If I swap the transistors the motor runs in one direction but one of
the transistors gets really hot.

Thanks for all the help.
Raul
 
Ok, I re-did the board but still no dice. Here are pics of how it sits
now.

http://www.asianhound.com/motor.html

If I swap the transistors the motor runs but one of the transistors
gets really hot.

Now what am I doing wrong?
Thanks for the help.
Raul
 
"Raul" <webmaster@2minclip.biz> wrote:

Ok, I re-did the board but still no dice. Here are pics of how it sits
now.

http://www.asianhound.com/motor.html

If I swap the transistors the motor runs but one of the transistors
gets really hot.

Now what am I doing wrong?
Click to expand...
Several things, including my suggestion that you *draw* the schematic
so that we can be clear what you are doing. It doesn't have to be a
work of art. Just identify all connections clearly, and photograph
*that* instead of your breadboard.

Also, if that's 3V you're using for the 741, it's too low a voltage.

--
Terry Pinnell
Hobbyist, West Sussex, UK
 
"Raul" <webmaster@2minclip.biz> wrote:

Here are pics of the
current setup.

http://www.asianhound.com/motor.html

If I swap the transistors the motor runs in one direction but one of
the transistors gets really hot.
Click to expand...
You are still only using 2 connections on the op-amp chip.

It needs at least 4 connections, input, output, plus power and minus
power.

The power connections are not shown in some schematics, but the op-amp
always need power to work.

One wire from the pot is not connected to anything..?

Your pictures are very good, and they make it easy to help you. It is
easy to see how the circuit actually is connected.

You need to check all connections of all components on the schematic and
in the real breadboarded circuit.



--
Roger J.
 
Ok, I put up some more images. I don't know the pin numbers for the
op-amp on the schematic. I didn't draw it. A guy named Brian did when I
first posted my problem. I'm a novice. I just make bugbots from books
as a hobby. The schematic shows three connections to the the amp. So
I've got three. That's probably the problem, he assumed I knew
something... My wife does that sometimes also.

Raul
 
I'm sorry to say Robert it still doesn't work. I don't know what I'm
doing wrong. Am I supposed to have two power supplies? Here are the
lastest pictures if you want to have a look.

http://www.asianhound.com/motor.html

I you guys feel like I'm wasting your time just let me know and I won't
bug you anymore.

Thanks, Raul
 
On 7 Dec 2004 06:32:24 -0800, "Raul" <webmaster@2minclip.biz> wrote:

I'm sorry to say Robert it still doesn't work. I don't know what I'm
doing wrong. Am I supposed to have two power supplies? Here are the
lastest pictures if you want to have a look.

http://www.asianhound.com/motor.html

I you guys feel like I'm wasting your time just let me know and I won't
bug you anymore.

Thanks, Raul
Click to expand...
The connection on the op-amp that you have labelled as pin 4 should
really go to the inverting input, pin 2, and your pin 7 connection
should really go to the non-inverting input pin 3.

The op-amp also need power supply connections, which are not shown on
the schematic, Pin 4 goes to the negative power supply, and pin 7 goes
to the positive supply.

The two batteries should be connected in series. The black lead of
the top battery should be connected to the red lead of the bottom one.
This point is "ground", and the black lead of the motor should connect
to it.

Then the red lead of the top battery becomes your "+V", and connects
to the 2N3904 collector and to the op-amp pin 7 and to the pot red
lead.

The black lead of the bottom one becomes the "-V", and connects to the
2N3906 collector and to the op-amp pin 4, and to the pot blue lead.

--
Peter Bennett VE7CEI
email: peterbb4 (at) interchange.ubc.ca
GPS and NMEA info and programs: http://vancouver-webpages.com/peter/index.html
Newsgroup new user info: http://vancouver-webpages.com/nnq
 
Ok. Could you check the drawing and make sure I am connecting the
transistors correctly. I'm off to the store to buy some 9v batteries.
http://www.asianhound.com/motor.html

Thanks, Raul
 
Terry, sorry about that. When I got the new schematic I stripped
everything off the board and started from scratch. The last photo was
not valid anymore. Thanks for the info about the ground.
Raul
 
Terry, I'm sorry about that but I had stripped the board when I got the
new schematic, so the photo wasn't valid any more. Thanks for the info
about the ground though.

Raul
 
On Wed, 08 Dec 2004 18:34:33 GMT, Robert Monsen
<rcsurname@comcast.net> wrote:


This is all just like tube terminology (as I'm learning). Tubes have a
cathode, also called a filament, which emits electrons into the space
around the filament.
Click to expand...
In most tubes, the cathode is indirectly heated - the filament or
heater is inside the cathode, but electrically insulated from it.

However, there are some directly heated tubes, where the filament also
acts as the cathode.

--
Peter Bennett VE7CEI
email: peterbb4 (at) interchange.ubc.ca
GPS and NMEA info and programs: http://vancouver-webpages.com/peter/index.html
Newsgroup new user info: http://vancouver-webpages.com/nnq
 
"Raul" <webmaster@2minclip.biz> wrote:

Your right, I could just but a new RC unit and do it that way, by
skipping the servo, but in the unit I have, I have one free control and
one free servo. In the unit I can't change out the servo for an
electronic motor control without changing the reciever control board.
So I want to control the pot with the remaining servo.
Click to expand...
Okay, I just mentioned it in case you didn't know about direct motor
control units.



--
Roger J.
 
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