Hi to you all newbee on forum would like some help please

billrobo1 · Joined: 05 Jul 2005 Posts: 1 Location: wales

Hi all hope you are all well
my problem is i would like to slow down an motor that is 12v and gives out 6amp when running (i think)the motor is off a windscreen wiper and i would like to slow it down preferably veriable, i have had a look on various weby`s but i really am unsure what i am after to do the job if anybody can shed some light i would be very greatfull

Guest

Depends on the use but I would use a pulse width type like the one in the link below as the D.C motor would have it's constant +12V applied to the "+" terminal with the 2N3055 transistor (rated up to 15A) between the "-" and 0V. You could use a heatsink on this if it runs warm but another advantage of PWM control is less heat is generated as it is switching the power to the motor "on" and "off" to vary the speed rather than using resistors or voltage/current varying circuits. Just a thought.
Another thing is firms like Maplin Electronics often supply such kits with full instructions.

http://circuitos.tripod.cl/schem/r27.gif

http://www.onsemi.com/pub/Collateral/2N3055A-D.PDF

http://www.uoguelph.ca/~antoon/circ/car912.htm

Guest · Posted: Sun Jul 10, 2005 6:35 am Post subject:

Windscreen wiper motors are usually 2 speed anyway, can you switch it to a lower speed? What do you want to do with it? Maybe you could gear it down?

RGP · Guest

you could either use a variable resistor but a powerfull one like 10k/3W
you conect the 1st and 2nd leg to the 12v and the 3rd to the motors +phase