View Single Post
  #26   Spotlight this post!  
Unread 20-12-2005, 01:43
sciguy125 sciguy125 is offline
Electrical Engineer
AKA: Phil Baltar
FRC #1351
Team Role: College Student
 
Join Date: Jan 2005
Rookie Year: 2004
Location: Sunnyvale, CA
Posts: 519
sciguy125 has a reputation beyond reputesciguy125 has a reputation beyond reputesciguy125 has a reputation beyond reputesciguy125 has a reputation beyond reputesciguy125 has a reputation beyond reputesciguy125 has a reputation beyond reputesciguy125 has a reputation beyond reputesciguy125 has a reputation beyond reputesciguy125 has a reputation beyond reputesciguy125 has a reputation beyond reputesciguy125 has a reputation beyond repute
Send a message via AIM to sciguy125 Send a message via MSN to sciguy125 Send a message via Yahoo to sciguy125
Re: Cheapest and easiest way to slow down a motor

Quote:
Originally Posted by sanddrag
I don't know what makes up a dimmer switch for lights in a house or office but would that work for 12VDC? (forgive me, I'm not really an electrical guy).
Apparently, they won't work. I just read an interesting article on Howstuffworks. They take advantage of the AC to turn the bulb off for a little while at the beginning of each half cycle.

I might get my head bitten off for suggesting this dreaded device again, but maybe you can use a 555. I'm pretty sure it will run on 12V. To make a 50% duty cycle oscillator, it would only take the 555, two resistors, and two capacitors. Then, you could just feed that into a MOSFET. The motor only has to go one direction right? If so, you'd just the single transistor, not an entire h-bridge. You won't have to deal with trying to dissipate as much heat as the resistor will be putting out.
__________________

-----BEGIN GEEK CODE BLOCK-----
Version: 3.12
GE/S/P a-- e y-- r-- s:++ d+ h! X+++
t++ C+ P+ L++ E W++ w M-- V? PS+ PE+
5- R-- tv+ b+ DI+++ D- G
------END GEEK CODE BLOCK------