fan speed switching?

[mike]

Being completely clueless on circuit design I thought I'd try this NG to
seek some inspiration!

I have a standard 12v fan I'd like to toggle between two different speeds
using a momentary action switch. The fan speed is currently being changed
using a 62 ohm 7 watt ceramic resistor to drop the supply power.
I really havent got a clue where to begin.
Any pointers gratefully received!


Mike.

 

[Rich Grise]

"mike" <mikeybabes@beeteee_internet_dot.com> wrote in message news:<bfjeh3$ia0$1@sparta.btinternet.com>...

Being completely clueless on circuit design I thought I'd try this NG to
seek some inspiration!

I have a standard 12v fan I'd like to toggle between two different speeds
using a momentary action switch. The fan speed is currently being changed
using a 62 ohm 7 watt ceramic resistor to drop the supply power.
I really havent got a clue where to begin.
Any pointers gratefully received!


Mike.

Connect the switch across the resistor. When the switch is closed,
the fan runs fast. When the switch is open, the fan runs slow.
If you still find this confusing, I'd strongly recommend looking
up some basic tutorials - they're all over the place - try
http://www.google.com and search for "electronics tutorial" or
some such. From time to time, other regulars post links to
basics sites, too.

Good Luck!
Rich

 

[cpemma]

Rich Grise wrote:

"mike" <mikeybabes@beeteee_internet_dot.com> wrote in message
news:<bfjeh3$ia0$1@sparta.btinternet.com>...
Being completely clueless on circuit design I thought I'd try this
NG to seek some inspiration!

I have a standard 12v fan I'd like to toggle between two different
speeds using a momentary action switch. The fan speed is currently
being changed using a 62 ohm 7 watt ceramic resistor to drop the
supply power. I really havent got a clue where to begin.
Any pointers gratefully received!


Mike.

Connect the switch across the resistor. When the switch is closed,
the fan runs fast. When the switch is open, the fan runs slow.
If you still find this confusing, I'd strongly recommend looking
up some basic tutorials - they're all over the place - try
http://www.google.com and search for "electronics tutorial" or
some such. From time to time, other regulars post links to
basics sites, too.

Easy with a SPST toggle switch, but with a single *momentary* switch you'll

need something like a flip-flop driving a relay switch across the resistor,
with anti-bounce on your momentary switch.

There are some circuits on Terry Pinnel's site, including
http://dspace.dial.pipex.com/terrypin/Images/ToggleMoment.gif

 

[mike]

"cpemma" <cpemma@mexbroREMOVE.co.uk> wrote in message
news:bfmofn$pr5$1@newsg3.svr.pol.co.uk...

Rich Grise wrote:
"mike" <mikeybabes@beeteee_internet_dot.com> wrote in message
news:<bfjeh3$ia0$1@sparta.btinternet.com>...
Being completely clueless on circuit design I thought I'd try this
NG to seek some inspiration!

I have a standard 12v fan I'd like to toggle between two different
speeds using a momentary action switch. The fan speed is currently
being changed using a 62 ohm 7 watt ceramic resistor to drop the
supply power. I really havent got a clue where to begin.
Any pointers gratefully received!


Mike.

Connect the switch across the resistor. When the switch is closed,
the fan runs fast. When the switch is open, the fan runs slow.
If you still find this confusing, I'd strongly recommend looking
up some basic tutorials - they're all over the place - try
http://www.google.com and search for "electronics tutorial" or
some such. From time to time, other regulars post links to
basics sites, too.

Easy with a SPST toggle switch, but with a single *momentary* switch
you'll
need something like a flip-flop driving a relay switch across the
resistor,
with anti-bounce on your momentary switch.

There are some circuits on Terry Pinnel's site, including
http://dspace.dial.pipex.com/terrypin/Images/ToggleMoment.gif

Thanks so far people. The circuit on the quoted url seems ideal.
The fan is rated at 2.4w (200ma?) so maybe I'll need to use the relay
circuit as well.
Looks like I have some reading to do!

Mike.