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Wiring Up Lm1084 Regulators

Hey everyone.

Just making sure I'm correct on this, would this diagram be correct?
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Thanks,
Tech


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Synthiam
PRO
Canada
#1  
Hey Tech, I can verify that it looks good!
#2  
I have not used the 1084 but this is the wiring i use for 7805

I'm wondering why you are not using capacitors with the regulator between.



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the blue bar at top will be ground and the red bar is regulated 5v.
PRO
Canada
#3  
Good call with the missing Caps @Luis

The LM1084 does have a different pinout than the classic 7805, it's more like a LM317 pinout
#4  
I have soldered dozens of LM7805s into servo extension cables... all without caps... They seem to work flawlessly with pings and other 5v sensors I have been using. I have even used them with micro servos... Why do we need the caps?
PRO
Canada
#5  
Caps are used for input line filtering and keeping the output voltage stable (less voltage sag) when in high current demand situations.
#7  
I understand what a cap does... but with a device like a ping that uses such a low amount of current, would that still be an issue?
PRO
Synthiam
#8  
You won't need a cap:) As an electrical engineer, jeremie is trained to make everything super stable. However, the device you are connecting to the LM1084 most likely has a filter cap of it's own - otherwise i'm certain it isn't a microprocessor that you're running so it'll be fine:D
#9  
no that would be find to run the ping sensor with out the caps. but if you did use the caps then you could make a 5 v. break out because most of the other sensors will be looking for 5v. so you may can use it to power other such devices.
#10  
Hey guys...

I use this setup, but there's hardly and light coming from lights I wired up. (Yes they do light up on 5V from another battery pack) Direct to the battery the lights are bright as day. Going from my science homework, do I need a resistor or something before the power enters the regulator?

Any ideas?
#11  
Use a voltmeter and measure the input and output voltages.
#13  
Here's what I just got on ebay. They're small so they don't take up much room, input 4.75 to 20 vdc, output 1 to 17 vdc @ 1.8 amps.


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#14  
Thanks, but I want to figure out why these don't work. I found that the regulator has an ADJ mark on it, though the regulator on the ez-b v3 has a 5.0 mark instead. Could this be I got the wrong one?
#15  
Sounds like maybe you got something like a NTE1929 by mistake. They look about the same. I ordered an LM1084 from an ebay seller and wound up getting a TIP310C transistor instead. It was only like $1 so I didn't bother trying to return it.

Alan
#17  
Any ideas? Does everyone think I got duds? Or is there something related to the ADJ marking on them.
#18  
There is an adjustable version of the LM1084, and that is what you have.

http://www.ti.com/product/lm1084

"The LM1084 is available in an adjustable version, which can set the output voltage with only two external resistors. It is also available in three fixed voltages: 3.3V, 5.0V and 12.0V. The fixed versions intergrate the adjust resistors.
"

My ability to read schematics is too out of practice to follow the diagram on that page, but apparently you use resisters to set the adjustable output.

Alan
#19  
@Tech... How Many do you need? I have some LM1084 (5V versions)... Just need your mailing address so I can mail them out to you....
#20  
Thanks Richard, but I'm not comfortable with giving out my mailing address. Thanks for the offer though. I guess I have to buy the right version this time.
#21  
No worries... I was going to give you them for free... If you want them email me at ryersonroofing(at)yahoo dot com

:)
#23  
Yes, according to the ebay title, they would appear to be the ones you seek.
PRO
Canada
#24  
Hi @Technopro,

You could still use the adjustable version of the LM1084 if you have a few common resistor values and follow the pictured diagram:

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Use a R2 value of 1kohm and an R1 value of 330ohms and it should give you a value of 5V. Equation is 1.25V(1 + R2/R1) = 1.25V(1+1000/330) = 5.04V
#25  
Thanks Jeremie, but I don't have any resistors or anything like that. I still have to order the diodes for those relays!

I sure hope they are Robot-doc!