# I think I need an electrician...



## MRGromPro (Apr 10, 2008)

Ok so let me get right to it since I expect this to be a bit long. What I need to do is power a Enlight Combo Spy Smart Fan Controller/Temp Sensor unit direct to a regular wall outlet.
Here is a pic
Front










Back (minus the hard drive, I do not need to power anything but the fan controller)









Now in the past I've powered other devices such as THIS fan controller/temp sensorsuccessfully by just splicing the power wires to a 12V 500mA or 1000mA box plug like is used to charge most cell phones. Unfortunately though the Enlight-EN5601500-Combo-Spy doesn't power on with either a 500mA or 1000mA plug. Well it kind of powers up, it lights up, but it just beeps real loud and shows nothing on the display. Works fine if I plug it into my computer though so I know it works.
I'm not really good at knowing volts and amps and stuff so if someone could tell me what my computer is giving it that my normally used box plug isn't or what mA plug I need I'd appreciate it. I have a 12V 2000mA plug I could try but I'm scared to as the 1000mA plug made the alarm in it scream like a mofo!


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## Koot (Nov 25, 2007)

The unit is probably designed to run off a computer's 5 volts DC power supply. If you tried it using 12 volts from a 120 volt to 12 volt converter you may have damaged it, even if it has a built -in voltage regulator. Hopefully it is still okay. 

The unit's design voltage (e.g. 5 volts) needs to supplied within a +/- 5% to 10% tolerance. The unit's ampacity (current) draw needs to be a consideration of the power supply or converter. The unit should have the voltage and the current or wattage requirements somewhere on the device or in the manual. Your PC's power supply has plenty of ampacity to handle this unit, and I strongly suspect the unit was designed to be powered from the PC's 5 volt power supply. I hope you didn't damage it.


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## MRGromPro (Apr 10, 2008)

No its not damaged. I can go back and forth from the 12v 500-1000mA box plug to my PC and it works fine in the PC. Do you think a unit like in the pic below might help me trouble shoot what it needs to fire up right?










...its only 300mA though. Reason I went to powering these types of units with a 1000mA plug (use to use a 500mA plug) is because it gave me more power and higher fan RPM's which is desirable. Of course that was on a different type of fan/temp sensor controller that actually worked on a plug like I have.


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## Koot (Nov 25, 2007)

I'm glad it still works as confirmed by you powering it up in your PC.

I would try powering the unit up using 5 volt DC using the multi-tap converter shown in your last post. 300mA should be plenty of ampacity unless you have added an optional hard drive.


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## MRGromPro (Apr 10, 2008)

No the only thing I do with these devices is power them off a wall socket run 3 80MM PC fans with them. Why when I use a 1000mA plug on THIS unit does it power the fans a lot better then a 500mA box plug? Made me think milli-amps were important and I wonder if a 5v plug with more mA would be needed??

...and an even better question is why would one run off a 12v 1000mA box plug and the other require a 5v?


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## Koot (Nov 25, 2007)

I understand the purpose of the unit better now. I guess I should have known that it was being used to control fans. I suspect that the 3 fan's combined amperage was taxing the 500mA converter and therefore the 1000mA converter was able to supply the necessary current, thus allowing the fans to run faster. When a power supply (or converter) is at the threshold of ampacity the voltage drops, which in your case would make the fans run slower. 

Since I now understand that you're using the control to power the 3 fans I would like to know the combined amperage of these 3 fans. Then, we can determine what total ampacity you will need with a resonable additional ampacity for safety sake.


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## MRGromPro (Apr 10, 2008)

don't know the amerage of the fans, or each heat/fan controller for that matter But you can look at what specs there here on newegg
those are the ones I use.

Again though why would one work fine off 12v power and the other not and need 5v? I'm just curious so I better understand. 

Thanks a tone for the help thus far BTW :up:


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## Koot (Nov 25, 2007)

MRGromPro said:


> No the only thing I do with these devices is power them off a wall socket run 3 80MM PC fans with them. Why when I use a 1000mA plug on THIS unit does it power the fans a lot better then a 500mA box plug? Made me think milli-amps were important and I wonder if a 5v plug with more mA would be needed??
> 
> ...and an even better question is why would one run off a 12v 1000mA box plug and the other require a 5v?


You've got me now! Unless the unit pulls more current than I think it should, it should not be anywhere close to needing about .5 amps or 500mA. Does the unit or the manual not say what the voltage and amperage/wattage is?


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## Koot (Nov 25, 2007)

The controller unit is designed to be installed into a drive space and powered from the PC's power supply with the four pin plug. I'm still confused however why you are powering the 3 80mm fans off a 12 volt converter installed in a 120 volt receptacle. Assuming the fans are normal 12 volt fans, can't you powwer them off your PC's power supply, which is the way (I think) the controller unit is designed to be used?


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## MRGromPro (Apr 10, 2008)

Hehe,.. ya I guess it might make things a bit more understandable for ya if you knew what I was using it for eh? Go to myspace.com/mrgrowpro to see first hand. But in short I need the temp sensors and LCD read out of the device, not just to have three fans powered.

As for spec's of the two units this is what I can find.
The Enlight unit says it can power 1000mA or 12 watts per fan max. Nothing really about what the unit itself needs to run right though.

The pic below is a scan I made of the info from the DigitalDoc 5










...hope this helps figure out whats needed!


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## Koot (Nov 25, 2007)

Okay, that helps! Your controller can control fans up to 1200 watts or 1 amp of fan amperage. Your fan wattage divided by voltage (12 volts) equals the amperage. 80mm fans can vary in the amount of amperage they draw, so you must have three (3) fans with a total combined amperage of less than 1 amp or 1200 watts for your controller to reliably work. Your 1000mA plug-in converter would be the best choice since it has the most ampacity. You cannot have too much ampacity, but you can have too little. Also, the controller's amperage draw is miminal with the LED lights, etc. - as long as you do not have the optional hard drive.

The small plug-in converters you have tried (500mA and 1000mA) are oftentimes not [voltage] regulated very well at all, so it could be that they are delivering more or less than the desired votage.


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## MRGromPro (Apr 10, 2008)

with the digitaldoc 5 it has a volt meter and I've noticed it runs anywhere from a half vote lower or higher then 12v but still operates. unfortunately i think they stopped making that item so I've been forced to find a different unit. Weird to me one would only need 5v and the other 12 but soon as i can ill give a 5v 1000mA plug a shot and let you know if it works.


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## MRGromPro (Apr 10, 2008)

Ok I think were on to something,...
I just tried a 5.8v 1000mA plug (times like this it's nice to have a closet full of crap) and it fired the Enlight Combo Spy up right this time but the one fan I have hooked up only spins are 1300rpm's where as if I hook the unit to my pc I can get one all 4 fans to spin at 2800 rpm's. Right volts finally but need more amps?


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## MRGromPro (Apr 10, 2008)

if I'm right, ya think a couple of these: http://cgi.ebay.com/BRAND-NEW-5V-3A...er-supply_W0QQitemZ220221596402QQcmdZViewItem might do the trick for 3 fans?


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## Koot (Nov 25, 2007)

MRGromPro said:


> Ok I think were on to something,...
> I just tried a 5.8v 1000mA plug (times like this it's nice to have a closet full of crap) and it fired the Enlight Combo Spy up right this time but the one fan I have hooked up only spins are 1300rpm's where as if I hook the unit to my pc I can get one all 4 fans to spin at 2800 rpm's. Right volts finally but need more amps?


I'm still not totally sure exactly what you are doing (source of voltage supply for the controller and source of voltage supply for the fans), nor exactly how the controller is actually supposed to work with reference to the source of voltage to the fans.

Your message (quoted above) tends to make me think that when you have the controller powered with 5 volts (which makes it power up properly according to you) and the controller is feeding this same 5 volts to the fans - not 12 volts, which is the voltage (I think) you believe you are supplying to the fans. It stands to reason that "if" you are supplying 5 volts (instead of 12 volts) to the fans that you will have around 1300rpms instead of 2800rpms. 5 volts/12 volts = 0.41667 and 0.41667 x 2800rpms = 1167rpms which is very close to the 1300rpms you say you are getting when the controller is supplied by 5 volts.

This fan rpm scenario tends to make me think that even though you are suppying the controller with 5 volts (which makes the controller happy) it is also supplying the fans with 5 volts too...even though you might think you are supplying the fans with 12 volts via a separate plug-in converter. [This is where I'm confused about the wiring setup you have.]

I am assuming the controller has the ability to control a load (your fans) using a different voltage than what powers the controller itself. I believe this would be the case and the controller could control/switch/vary the load (e.g. your fans) using a different load voltage from a separate source. But for some reason, which I am unable to determine, your fans seem to be operating off of the same 5 volts as your controller - instead of the 12 volts that you say you are using to feed the fans. The controller itself apparently needs 5 volts to operate itself and needs to have the load voltage (12 volts) to ultimately power teh fans. I'm not so sure you have the fans voltage (12 volts) wired correctly to the controller so the controller can actually "control" the fans, which needs [up to] 12 volts for full rpms.


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## MRGromPro (Apr 10, 2008)

Ok so I did some testing and I'm back 
I dug a volt meter out of my closet and figured out that the yellow wire on a computers power plug pumps out 12V and the red wire 5V. Now the DigitalDoc5 unit I have been using for months (which has unfortunately been discontinued now) worked with a 12V plug. Three fans ran slow at 12V 500mA but fast at 12V 1000mA which makes sense because I read HERE that this 80MM case fan (which is very similar in CFM to the ones I use) requires 250mA. 3 would draw 750mA and thus why a 12V 500mA plug didn't work as well as the 12V 1A plug.

The Enlight Combo as well as the NZXT SENTRY which I recently tested do NOT power up with just a 12V plug powering the there yellow wire. They require a 5V plug to there red wire and furthermore a 12V plug to there yellow wire to power the fans as well. This kinda sucks as it requires me to use both a 12V and a 5V plug to power one of these units alone with the fans but that does make everything function properly.

So I guess my question now is how would one go about powering a 5V and 12V draw with just one plug and cheaper then $10-$15 which is what two cost me roughly? 

Any ideas?


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## cwwozniak (Nov 29, 2005)

MRGromPro said:


> So I guess my question now is how would one go about powering a 5V and 12V draw with just one plug and cheaper then $10-$15 which is what two cost me roughly?
> 
> Any ideas?


You could try starting with a regulated 12 VDC supply with a current rating at least equal to maximum current drawn by both the 5 and 12 volt inputs to the controller. If the controller draws less than 1 amp on the 5 volt input you could then add a three terminal +5 Volt fixed voltage regulator like a #7805 and a couple of bypass/filter capacitors. The 7805 IC sells for $1.59 in single piece quantities at Radio Shack (Catalog # 276-1770).


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## MRGromPro (Apr 10, 2008)

cwwozniak said:


> You could try starting with a regulated 12 VDC supply with a current rating at least equal to maximum current drawn by both the 5 and 12 volt inputs to the controller. If the controller draws less than 1 amp on the 5 volt input you could then add a three terminal +5 Volt fixed voltage regulator like a #7805 and a couple of bypass/filter capacitors. The 7805 IC sells for $1.59 in single piece quantities at Radio Shack (Catalog # 276-1770).


hmmmm,... interesting. Thank you very much. I'm a lil confused by that since I don't know much about electronics but I get your general idea. Now for a noob question,.. would a 12V power supply plug work to power the yellow 12V *and* the red 5V wires sufficiently?

I see a pic of it on radioshack.com








To what would one solder those 3 prongs to?


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## cwwozniak (Nov 29, 2005)

Here is a link to an article on using the 7805 regulator. Your 12 Volt supply would feed both the +12 volt input to the controller and the input to the 7805. The output from the 7805 would then feed the +5 volt input to the controller. You do need the two capacitors show in the schematic diagram to keep the regulator IC stable. You could probably use the disc drive holder portion of the controller as the heat sink.

http://www.eleinmec.com/article.asp?20


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## Koot (Nov 25, 2007)

Yeah, needing two voltages has made it confusing and difficult for you to make it work in your particular application. cwwozniak has the easiest and cheapest approach to get the 5 volts (with a very low current draw) you need for the controller [itself] to work.

You'll want to use your 1000mA (1 amp) 12 volt adapter as the main power supply. Use the 7805 IC voltage regulator to feed the controller its required 5 volts. And the 12 volts from the adapter will be used for the fans. Since the controller [itself] only draws a tiny amount of current (at 5 volts via the 7805) your 12 volt adapter will still be capable of handling the fans. As cwwozniak suggested, you do not need any extra components on the 7805 (e.g. capacitors) to feed the controller its required 5 volts DC.

Google search 7805 IC wiring diagrams to learn how the 7805 chip's three pins are wired for input & output.


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## cwwozniak (Nov 29, 2005)

Koot said:


> As cwwozniak suggested, you do* not *need any extra components on the 7805 (e.g. capacitors) to feed the controller its required 5 volts DC.


  

I believe that I said that the two capacitors* are *needed. As a matter of fact they need to be fairly close to the pins of the 7805 device. Unless the design of the 7805 has changed over the years, I thought that it could break into high frequency oscillation without the bypass caps.


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## MRGromPro (Apr 10, 2008)

What the the two capacitors? I thought all i'd need was a 7805 device


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## cwwozniak (Nov 29, 2005)

MRGromPro said:


> What the the two capacitors? I thought all i'd need was a 7805 device


Figure 2 on the page in the link in my earlier post:










0.1 uF bypass capacitors to ground on the input and output sides.

The capacitor on the output side is optional and may not be needed if the controller module has any kind of power input filter capacitor inside of it.

A capacitor on the input side may not be needed if the 12 Volt power supply feeding the 7805 has its output filter capacitor very close to the 7805 part. A couple of feet of wire between any capacitor in your AC adapter and the 7805 is probably not considered as being very close.


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## Koot (Nov 25, 2007)

cwwozniak said:


> I believe that I said that the two capacitors* are *needed. As a matter of fact they need to be fairly close to the pins of the 7805 device. Unless the design of the 7805 has changed over the years, I thought that it could break into high frequency oscillation without the bypass caps.


I incorrectly read your post about the capacitors. However, I do not think caps are needed, especially on the input side. The 12 volt adapter will have filtering caps and we're just regulating the dc voltage from the adapter. It certainly wouldn't hurt to add a .01 ceramic cap or a 10uF tantalum cap (to ground) on the output (and even input side), but I don't see the need.


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## cwwozniak (Nov 29, 2005)

Tried to find a definitive answer on whether or not any bypass capacitors are needed and found conflicting information on the web site of a company that makes the 7805 part.

A National Semiconductor spec sheet (link to PDF version) for the LM78M05 part says that a bypass capacitor is needed on the input side if the main raw DC filter capacitor is more than 4 inches away from the input. An output cap is not needed but it can improve transient response.

Then I found an article on the same company web site. It is written by a member of the National Semiconductor technical staff and it states _"... linear regulator semiconductors sold commercially like the LM7805 type devices: they require no input or output capacitor and are completely stable under virtually any operating conditions. ... The main reason the 7805 is unconditionally stable ..."_

My $0.02 worth of opinion on the matter is that if it was for a circuit I was building for my own use, I might skip the capacitor. If I was putting the circuit into a product that I was selling, there might always be the slim chance that a problem might occur later on because of the missing capacitor. The cost of shipping a single returned unit, repairing it, and shipping it back to an annoyed customer would probably cost a lot more than just putting the capacitor in every unit to begin with.


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## Koot (Nov 25, 2007)

cwwozniak said:


> Tried to find a definitive answer on whether or not any bypass capacitors are needed and found conflicting information on the web site of a company that makes the 7805 part.
> 
> A National Semiconductor spec sheet (link to PDF version) for the LM78M05 part says that a bypass capacitor is needed on the input side if the main raw DC filter capacitor is more than 4 inches away from the input. An output cap is not needed but it can improve transient response.
> 
> ...


Yeah, if I was using the regulator for an electronic circuit I would definitely use caps on the input and output, however since the load is inductive [fans] I really do not see the need for caps. The adapter has a bridge to convert AC to DC that uses filtering caps and also probably a RC network to keep the ripple down. That upstream capacitance should provide some stability at the LM7805 regulator. MRGromPro could always play with it not using caps and see how it responds.


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## JohnWill (Oct 19, 2002)

You should most certainly use the caps, I've never seen those regulators without them. I have had them oscillate without the caps, so I'd stick them on there. 

It may not immediately break into oscillation, but rather wait until a certain output loading condition.

What's the big deal about putting a couple of 10 cent caps on it anyway?


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## MRGromPro (Apr 10, 2008)

the price is right,.. i just still have no idea how to wire any of this 
looking at those schematics is kinda hard to understand, doesn't pertain to my situation so much so but maybe once i get a few in my hand ill better figure out what ends to solder to what.


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## Koot (Nov 25, 2007)

>





> i just still have no idea how to wire any of this
> looking at those schematics is kinda hard to understand, doesn't pertain to my situation so much so but maybe once i get a few in my hand ill better figure out what ends to solder to what.


You have three pins on the 7805 regulator chip. With the chip face-up the pin on the left is your Input, which is where you'll wire your 12 volt positive wire. The middle pin is Common (i.e. Ground), which is where you'll wire the adapter's negative wire. The pin on the far right is your Output.

The diagram (image) above shows "Smooth DC Output" on the left-hand side, but is actually your Input [from your 12 volt adapter]. "Vs" (far left pin) is where you feed the adapter's positive (+) wire coming from your 12 volt adapter and "0V" (middle pin) is where you feed the adapter's Ground (-) wire.

You will have "5 volts DC Regulated Output" coming from the far right-hand pin "+5V" and the middle pin "0V". As the diagram shows the middle pin is "Common" to both the Input and Output, thus the adapter's negative wire goes to this pin as well as the negative wire for your regulated 5 volt Output.


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## wacor (Feb 22, 2005)

Hey Koot I see you are retired. Were you an electrical engineer??

And how big of a Ham operater nerd are you?? If you were/are an obsessed Ham I bet you have had contact with an old buddy of mine.


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## cwwozniak (Nov 29, 2005)

Here is quick picture diagram I put together in Photoshop that should give a pretty good idea of were to solder in the capacitors and the wires.

EDIT: As I mentioned before, the metal tray that is supposed to hold the hard drive can be used as the heat sink. You shouldn't need to electrically isolate the tab from the tray when you bolt it in. You just need to maybe bend the 7805's leads away from the tray a bit so that they short to the tray.

Once you confirm each assembly is working correctly, you could put a blob of RTV over the 7805's wiring to keep everything in place


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## Koot (Nov 25, 2007)

wacor said:


> Hey Koot I see you are retired. Were you an electrical engineer??
> 
> And how big of a Ham operater nerd are you?? If you were/are an obsessed Ham I bet you have had contact with an old buddy of mine.


Yes I am retired, but my profession was in something far different from electrical engineering. However, I suspect I could pass the unlimited electrical licensing test.

I was first licensed when I was 12 years old. I've been in and out of the hobby over the years, but haven't been active recently. I used to design and build some of my equipment, mainly big linear amplifiers. The hobby offered me a lot of fun and allowed me to learn a lot about electronics and electricity. I also enjoyed joining a large group of friends on 75 meters during the evening hours and contest on weekends. I've even won a few worldwide contests over the years. Ham radio used to be much more active and fun than it is now. Golf has always been my number one hobby since childhood.

Here's some pictures of a linear amplifier I designed and built.


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## Koot (Nov 25, 2007)

Here's a picture of what some of my Ham radio station equipment looked like, but my main hobby has always been golf... Don't ask me about sports cars!

How about you wacor - what kind of nerdy hobbies do you have?


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## wacor (Feb 22, 2005)

Koot said:


> Here's a picture of what some of my Ham radio station equipment looked like, but my main hobby has always been golf... Don't ask me about sports cars!
> 
> How about you wacor - what kind of nerdy hobbies do you have?


No nerdy hobbies unless you consider golf nerdy.

my buddy built his own rigs. Heathkit as I recall was the make. He moved up into northern part of the lower penninsula in MI. Put up a tower that i think is 40' tall. Rarely see him anymore but he was consumed by it. he would even take his mobile unit and rig up a mobile antenna on fishing trips.


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## Koot (Nov 25, 2007)

wacor said:


> No nerdy hobbies unless you consider golf nerdy.
> 
> my buddy built his own rigs. Heathkit as I recall was the make. He moved up into northern part of the lower penninsula in MI. Put up a tower that i think is 40' tall. Rarely see him anymore but he was consumed by it. he would even take his mobile unit and rig up a mobile antenna on fishing trips.


Yeah, Heathkit used to make kits for transmitters, receivers, amplifiers, etc. that included all the parts and you just followed the instructions. I preferred designing and laying out my own circuitry and obtaining the necessary parts. It was much more gratifying that way instead of buying a kit that included everything you needed. I've built a number of high-power amplifiers using parts that were not available in kit form or from the equipment manufacturers. Years ago when I lived out in the country with a large number of acres I had towers and beams, but I now have properties inside city limits.


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## n2gun (Mar 3, 2000)

Nice station Koot


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## Koot (Nov 25, 2007)

n2gun said:


> Nice station Koot


TX Jerry, 73


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## Koot (Nov 25, 2007)

MRGromPro - Let us know how your project is going. 

PS - Sorry for getting off-topic a little...


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## MRGromPro (Apr 10, 2008)

IM BACK!! 
...and still unable to get the Enlight unit I pictured in my first post to work via wall socket power. I haven't had time to mess with it (or the 7805 item) you all tried so much to help me with till now. But since I acquired a 5V 3A power plug I thought I would try an easier way to fire it up and then maybe mess with wiring up a 7805.

Ok so I have the 12V 1A box plug wired to the yellow 12V wire and a ground,.. Also a 5V 3A box plug wired to the red and a black ground and low and behold the thing fires right up when I plug them in! Temp sensors work too, buuuuuuuut when I plug a fan into the unit the LCD goes blank and gives me a sick repeating beep. The fan does fire right up though, Ha!
You can set the Enlight to monitor fan RPM or not. If I tell it not to, basically tell it no fans are hooked to it all the fans work and the LCD as well. Soon as I tell it monitor a fan RPM's though it goes dead and starts beeping. 
I know I got the right volts to the right wires this time around so my only other thought is I have too many or not enough amps?

The device works fine if I hook it to a PC so can anyone tell me how many amps a PC's 5V power supply pushes?


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## cwwozniak (Nov 29, 2005)

MRGromPro said:


> Soon as I tell it monitor a fan RPM's though it goes dead and starts beeping.
> 
> The device works fine if I hook it to a PC


Just to confirm, it works fine with fan speed monitoring enabled when powered from the PC?



MRGromPro said:


> so can anyone tell me how many amps a PC's 5V power supply pushes?


A typical 350 watt PC power supply can put out maybe a total of 20 Amps on the +5 VDC outputs and maybe a total of 23 Amps on the +12 VDC outputs


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## MRGromPro (Apr 10, 2008)

Yes it works fine and monitors fan RPM's when hooked to my PC.... and I have an update,... now it works fine and monitors RPM's when hooked to a wall socket if I use a 5V 2A box plug. Doesn't like the 5V 3A plug, works with the 5V 2A. Explain that to me if a PC is giving it as much as 20A, LOL


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## MRGromPro (Apr 10, 2008)

Although everything is working like it's suppose to, like if it were hooked to a PC, I'm not really getting the max CFM and in turn air flow from the three fans I have hooked up. The 2 exhaust fans are restricted a bit what with them blowing through a thin carbon filter (for odor control), there running at 2000-2100 RPM's,.. and the intake fan is running at 2200 RPM's with no restriction. I guess I cant complain them being rated at 2500 RPM max.


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## cwwozniak (Nov 29, 2005)

MRGromPro said:


> Doesn't like the 5V 3A plug, works with the 5V 2A.


It could be that the [email protected] adapter is bad or it may be a simple unregulated power supply whose voltage drops to much too keep the controller happy as the load increases.


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## MRGromPro (Apr 10, 2008)

5V 3A dropping below 2A though? I was thinking 3A was too bookoo but if a PC gives it 20A christ who knows. Is there any way to tell how regulated the power is coming from one of the plugs? I have a multimeter but I'm not real knowledgable at using it. Here is a pic of it.


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## cwwozniak (Nov 29, 2005)

Assuming you have typical test leads that go with the multimeter, plug the black lead into the bottom jack of the meter marked "COM" and plug the red lead into the next jack up marked "Volt-Ohm-mA". For testing 5 and 12 volt supplies, set the meter's knob pointer to 20 in the DCV section.

Work out your power supply and load (Fan controller unit) cable connections so that the meter can stay connected to the supply while you can connect and disconnect the load.

Connect the meter's red lead to the positive (+) output of the supply and the black lead to the negative (- or ground) output of the supply.

Measure the output voltage with no load connected. A regulated supply should measure pretty close to its rated voltage. A simple unregulated supply may output almost a 50% higher voltage.

Connect your load. A regulated supply's voltage should not change as long as you are not drawing more than its maximum current limit. An unregulated supply's output voltage will drop under load. An unregulated supply may also have show a large amount of AC ripple voltage under load that may not be that easy to detect with your meter.


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