Im being thick Variable Resistor to Rheostat - Page 2 - diyAudio
Go Back   Home > Forums > General Interest > Everything Else

Everything Else Anything related to audio / video / electronics etc) BUT remember- we have many new forums where your thread may now fit! .... Parts, Equipment & Tools, Construction Tips, Software Tools......

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 11th May 2011, 09:34 AM   #11
diyAudio Member
 
sofaspud's Avatar
 
Join Date: Nov 2005
Location: San Antonio
Quote:
You can take a PC molex adapter and mod it to output 7v as the lines on the psu allow this. Google it'll show you loads.
No, no, I'll take your word. My 5V works fine thank you. If'n it ain't broke...
Maybe your controller needs 12V minimum and your 5+ amps worth of fan is dropping the voltage output. Have you monitored the input to the controller?
The 555 and FET circuit I mentioned could have been built, cased and installed in the time we've been discussing this.
__________________
It is error only, and not truth, that shrinks from enquiry. - Thomas Paine
  Reply With Quote
Old 11th May 2011, 10:07 AM   #12
diyAudio Member
 
Join Date: Feb 2010
Quote:
Originally Posted by sofaspud View Post
No, no, I'll take your word. My 5V works fine thank you. If'n it ain't broke...
Maybe your controller needs 12V minimum and your 5+ amps worth of fan is dropping the voltage output. Have you monitored the input to the controller?
The 555 and FET circuit I mentioned could have been built, cased and installed in the time we've been discussing this.
11.75V input control set to min

11.51V input control set to max

1.01V output set to min

11.45V out put set to max

Around 10.86V the grinding stops and all fans spin

I've no idea where even begine with a 555, FET and such hense why i bought this off ebay

Last edited by Pjalchemist; 11th May 2011 at 10:19 AM.
  Reply With Quote
Old 11th May 2011, 12:21 PM   #13
diyAudio Member
 
sofaspud's Avatar
 
Join Date: Nov 2005
Location: San Antonio
Apologies, but none of the measurements make any sense to me.
Measure the wires you use to power the fans. No controller, no fans, nothing but the wires (that's 1).
Then connect the controller (with the fans connected to it) to the power.
Measure the wires again turning the controller adjustment from minimum (that's 2) to maximum (that's 3).
So we have 3 voltage readings.

Oh yeah. Do tell what is the input control?
__________________
It is error only, and not truth, that shrinks from enquiry. - Thomas Paine

Last edited by sofaspud; 11th May 2011 at 12:34 PM.
  Reply With Quote
Old 11th May 2011, 04:38 PM   #14
diyAudio Member
 
Join Date: Feb 2010
Each wire? So each wire per fan? Input is just a 25K varible resistor as shown in the ebay link
  Reply With Quote
Old 11th May 2011, 05:03 PM   #15
Boofers is offline Boofers  Canada
diyAudio Member
 
Join Date: Oct 2008
Location: Ontario
Blog Entries: 1
Hi. If you want your fans to just have two modes, full and quiet, you could just use a switch. In switch position 1 the fans are all in parallel, giving 12V per fan. For switch position 2 the fans will get about 6V each. I say "about" 6V each because some fans will hog a bit more current than others, but it will be close to half of 12. Just an idea. FYI the switch is a DPDT.
Click the image to open in full size.
  Reply With Quote
Old 11th May 2011, 06:45 PM   #16
diyAudio Member
 
sofaspud's Avatar
 
Join Date: Nov 2005
Location: San Antonio
Quote:
Each wire? So each wire per fan?
Maybe I should have written,"Measure the wires you use to power the controller" (that's 1).
Don't think 8, think 1.
__________________
It is error only, and not truth, that shrinks from enquiry. - Thomas Paine
  Reply With Quote
Old 11th May 2011, 07:51 PM   #17
diyAudio Member
 
Join Date: Feb 2010
Power from PSU to input of controler is 12.08V

What do i need to measure netxt?
  Reply With Quote
Old 11th May 2011, 07:59 PM   #18
diyAudio Member
 
sofaspud's Avatar
 
Join Date: Nov 2005
Location: San Antonio
Then connect the controller (with the fans connected to it) to the power.
Measure the wires again turning the controller adjustment from minimum (that's 2) to maximum (that's 3).
So we have 3 voltage readings.

What do you have connected to the white 3-pin header near the electrolytic caps?
__________________
It is error only, and not truth, that shrinks from enquiry. - Thomas Paine
  Reply With Quote
Old 11th May 2011, 08:02 PM   #19
Banned
 
Join Date: Jan 2008
Blog Entries: 2
Wire them all in parallel to the positive supply and the drain of a large MOSFET, wire the source to ground, wire a 10k resistor from the 12V to a 10k pot, wire the other side of the pot to ground and wire the wiper to the gate. You have to be aware that the FET will dissipate ~20W worst case, so you need some heatsinking.

w
  Reply With Quote
Old 11th May 2011, 08:03 PM   #20
diyAudio Member
 
Join Date: Feb 2010
Quote:
Originally Posted by sofaspud View Post
Then connect the controller (with the fans connected to it) to the power.
Measure the wires again turning the controller adjustment from minimum (that's 2) to maximum (that's 3).
So we have 3 voltage readings.

What do you have connected to the white 3-pin header near the electrolytic caps?
Measure the same wire i did for the volage feeding the controller? IE 12V input

(2) Control knob all the way to the minimum 12.02v

(3) Control knob all the way to maximum 11.38v

When turning to max it dips to 11.26v these rises to the above

A100K Verable Resistor - It came with the kit

Last edited by Pjalchemist; 11th May 2011 at 08:12 PM.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
variable resistor? studiostevus Digital Line Level 0 11th December 2010 08:28 AM
variable resistor akis Solid State 23 15th May 2010 06:44 PM
Do I need a resistor if Im going directly from rca... bundee1 Class D 1 6th April 2010 01:05 AM
Ohmite 32 ohm 300W rheostat power resistor boywonder Swap Meet 0 31st May 2009 01:37 AM
Using a variable resistor in the feedback loop. darren01 Chip Amps 9 30th December 2003 10:05 AM


New To Site? Need Help?

All times are GMT. The time now is 05:43 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2