Need info, 12v - 7v switch

Jim · 02-17-2002, 12:16 PM

Last summer when I was in the process of building my computer, I picked up a fan control switch from Nerdsbyte. It is a high-off-low toggle affair. (12v and 7v)

I never used it. I recall reading that the method in which the 7 volts are derived here is down and dirty. Something about using two negatives to get the 12 volt rail down to 7v using the 12v negative and 5v negative lines, I think.

To be clear, I have not trashed anything and have no argument with Nerdsbyte.

What I need here is a slight refresher on the subject, since I don't want to throw an imbalance into the power supply and cause a problem with voltages and my rig.

We got 12, 3.3, and 5 volts coming out of the power supply, so I am certain the 7 volts is begin pulled in a abnormal way.

I am sure I have 12v and 7 v out the device after checking with a VOM.

Anyway, let me know what you think, I may be better to off get a potentiometer, if I knew what to get and where. I will be using this to adjust speeds on two Panaflo 120 mm 12M's.

I also noticed after visiting Nerdsbyte's site, that this switch is no longer available.

Thanks much,
Jim

Leuf · 02-17-2002, 12:36 PM

You get 7 volts by connecting the return of the fan (black) to the 5v supply (red). Voltage is the potential difference between the two, so instead of +12 minus 0 (ground) it's +12 minus +5 = 7 volts. Give Brians fan control article a read:

http://www.procooling.com/articles/h...trol_met.shtml

I used to run my panaflo 120 mm at 7 volts, and now i use a rheostat - but I end up running it at about what the 7 volts gave me anyway - it just gives me the chance to crank it up when needed.

Jim · 02-17-2002, 05:05 PM

Leuf-

Thanks for the info, can you give me a spec on a rheostat I can get please?
Jim

Leuf · 02-17-2002, 06:07 PM

I use the pcmods.com rheobus - if you're just doing the one fan then that's of course overkill. I've seen something like this around a few places:

http://www.sidewindercomputers.com/rheosformc.html

zalman also has one, but it uses 3 pin connectors. Most of the rheostats you'll see on sites are 5 watts, you can't go too wrong.

Jim · 02-17-2002, 06:20 PM

Quote:

Originally posted by Leuf
I use the pcmods.com rheobus - if you're just doing the one fan then that's of course overkill. I've seen something like this around a few places:

http://www.sidewindercomputers.com/rheosformc.html

zalman also has one, but it uses 3 pin connectors. Most of the rheostats you'll see on sites are 5 watts, you can't go too wrong.

Yeah, I knew about that one, but my two 120 MM panaflo's are rated at .45 amps each almost a full amp for the two I will be using. So I think the Sidewinder is too small, or am I calculating incorrectly? That should be 10.80 watts, right?

Jim

Leuf · 02-17-2002, 07:40 PM

whoops, you're right, the 120 mm is just over 5 watts - so no go there. I think the zalman one is 6 watts. You might look into the LM317 voltage regulator, caseetc has a kit for it, but you only need 1 - the kit has 2

http://www.caseetc.com/cgi-bin/caseetc/F-397.html

Brians256 · 02-17-2002, 11:07 PM

If you go the voltage regulator route (a good option), take a look at Uller's LM317 tutorial. I give an URL linkage to his site in my fan speed control article. It takes all of five components to do it (three if you don't care about smoothing out the voltage with capacitors). It's darn easy and it works well. The only drawback is that using an LM317 means that you can't get a full 12V to the fan anymore because the LM317 consumes a bit of voltage. You can only get about 10.6V or 11V (I can't remember the exact number).

Jim · 02-18-2002, 06:43 AM

Thanks BRIANS256-

Is this located up in the FAQ section, your article I mean?
JIm

Brians256 · 02-18-2002, 09:13 AM

My article is here: http://www.procooling.com/articles/h...trol_met.shtml

Ryan Meyer's (Uller) article is here: http://casemods.pointofnoreturn.org/vregtut/

FAQ?

Jim · 02-19-2002, 08:18 PM

Brians256-

Thanks again for the info. Do you think the Case.ETC Baybuss 350 kit is a good value or is it best to round up the parts myself?

The Baybus 6A kit is $39.95 plus shipping. How hard is it to locate all the components?

Jim

Brad · 02-20-2002, 02:18 AM

the caseetc baybus kit is quite decently priced, it may be a little high, but you only have to pay one lot of shipping from one company, instead of from differant people, or driving around the place

Brians256 · 02-20-2002, 11:53 AM

Brad is right. The price for the baybus kit is not bad. However, it all depends upon how much you want to put things together. For seven dollars more you could get the Maelstrom, which is already assembled. That's not a lot for the amount of labour you'd save. Plus, the Maelstrom is very well done.

Me, I'd probably just get stuff from local distributors or from Radio Shack. But, it wouldn't look nearly as nice as the Maelstrom. Also, I tend to spend more than I should on parts because I get spare parts at the same time. I also spend money on tools. It's cheaper to buy them pre-assembled if you don't have the tools!

Jim · 02-20-2002, 12:23 PM

Brian-
yeah I was looking at that and thinking about the labor time as well.

thanks
Jim

02-17-2002, 12:16 PM	#1
Jim Cooling Savant Join Date: Feb 2002 Location: Illinois Posts: 389	Need info, 12v - 7v switch Last summer when I was in the process of building my computer, I picked up a fan control switch from Nerdsbyte. It is a high-off-low toggle affair. (12v and 7v) I never used it. I recall reading that the method in which the 7 volts are derived here is down and dirty. Something about using two negatives to get the 12 volt rail down to 7v using the 12v negative and 5v negative lines, I think. To be clear, I have not trashed anything and have no argument with Nerdsbyte. What I need here is a slight refresher on the subject, since I don't want to throw an imbalance into the power supply and cause a problem with voltages and my rig. We got 12, 3.3, and 5 volts coming out of the power supply, so I am certain the 7 volts is begin pulled in a abnormal way. I am sure I have 12v and 7 v out the device after checking with a VOM. Anyway, let me know what you think, I may be better to off get a potentiometer, if I knew what to get and where. I will be using this to adjust speeds on two Panaflo 120 mm 12M's. I also noticed after visiting Nerdsbyte's site, that this switch is no longer available. Thanks much, Jim

02-20-2002, 02:18 AM	#11
Brad Thermophile Join Date: Oct 2001 Location: Nuu Zeeelin Posts: 3,175	the caseetc baybus kit is quite decently priced, it may be a little high, but you only have to pay one lot of shipping from one company, instead of from differant people, or driving around the place __________________ 2x P3 1100's at 1400, Abit VP6, 2x Corsair 256mb PC150 sticks, 20gb 'cuda ATA-III, 2x 40gb 'cuda ATA-IV in raid 0. 20" Trinitron. No fans 2x 2400+ at 2288mhz (16.0 x 143), Iwill MPX2, 2x Kingmax PC-3200 256mb sticks, 4x 20gb 60gxp in Raid 5 on a Promise SX6000. Asus Ti4200 320/630. Cooled by Water

02-17-2002, 12:36 PM	#2
Leuf Cooling Neophyte Join Date: Dec 2001 Posts: 56	You get 7 volts by connecting the return of the fan (black) to the 5v supply (red). Voltage is the potential difference between the two, so instead of +12 minus 0 (ground) it's +12 minus +5 = 7 volts. Give Brians fan control article a read: http://www.procooling.com/articles/h...trol_met.shtml I used to run my panaflo 120 mm at 7 volts, and now i use a rheostat - but I end up running it at about what the 7 volts gave me anyway - it just gives me the chance to crank it up when needed.

02-17-2002, 05:05 PM	#3
Jim Cooling Savant Join Date: Feb 2002 Location: Illinois Posts: 389	Leuf- Thanks for the info, can you give me a spec on a rheostat I can get please? Jim

02-17-2002, 06:07 PM	#4
Leuf Cooling Neophyte Join Date: Dec 2001 Posts: 56	I use the pcmods.com rheobus - if you're just doing the one fan then that's of course overkill. I've seen something like this around a few places: http://www.sidewindercomputers.com/rheosformc.html zalman also has one, but it uses 3 pin connectors. Most of the rheostats you'll see on sites are 5 watts, you can't go too wrong.

02-17-2002, 07:40 PM	#6
Leuf Cooling Neophyte Join Date: Dec 2001 Posts: 56	whoops, you're right, the 120 mm is just over 5 watts - so no go there. I think the zalman one is 6 watts. You might look into the LM317 voltage regulator, caseetc has a kit for it, but you only need 1 - the kit has 2 http://www.caseetc.com/cgi-bin/caseetc/F-397.html

02-17-2002, 11:07 PM	#7
Brians256 Pro/Staff Join Date: Oct 2001 Location: Klamath Falls, OR Posts: 1,439	If you go the voltage regulator route (a good option), take a look at Uller's LM317 tutorial. I give an URL linkage to his site in my fan speed control article. It takes all of five components to do it (three if you don't care about smoothing out the voltage with capacitors). It's darn easy and it works well. The only drawback is that using an LM317 means that you can't get a full 12V to the fan anymore because the LM317 consumes a bit of voltage. You can only get about 10.6V or 11V (I can't remember the exact number).

02-18-2002, 06:43 AM	#8
Jim Cooling Savant Join Date: Feb 2002 Location: Illinois Posts: 389	Thanks BRIANS256- Is this located up in the FAQ section, your article I mean? JIm

02-18-2002, 09:13 AM	#9
Brians256 Pro/Staff Join Date: Oct 2001 Location: Klamath Falls, OR Posts: 1,439	My article is here: http://www.procooling.com/articles/h...trol_met.shtml Ryan Meyer's (Uller) article is here: http://casemods.pointofnoreturn.org/vregtut/ FAQ?

02-19-2002, 08:18 PM	#10
Jim Cooling Savant Join Date: Feb 2002 Location: Illinois Posts: 389	Brians256- Thanks again for the info. Do you think the Case.ETC Baybuss 350 kit is a good value or is it best to round up the parts myself? The Baybus 6A kit is $39.95 plus shipping. How hard is it to locate all the components? Jim

02-20-2002, 11:53 AM	#12
Brians256 Pro/Staff Join Date: Oct 2001 Location: Klamath Falls, OR Posts: 1,439	Brad is right. The price for the baybus kit is not bad. However, it all depends upon how much you want to put things together. For seven dollars more you could get the Maelstrom, which is already assembled. That's not a lot for the amount of labour you'd save. Plus, the Maelstrom is very well done. Me, I'd probably just get stuff from local distributors or from Radio Shack. But, it wouldn't look nearly as nice as the Maelstrom. Also, I tend to spend more than I should on parts because I get spare parts at the same time. I also spend money on tools. It's cheaper to buy them pre-assembled if you don't have the tools!

02-20-2002, 12:23 PM	#13
Jim Cooling Savant Join Date: Feb 2002 Location: Illinois Posts: 389	Brian- yeah I was looking at that and thinking about the labor time as well. thanks Jim

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)