Step 8: Schematic

Picture of Schematic
LED Projector II fan and LCD.PNG
LED Projector II fan.PNG
LED Projector II no adds.PNG
12v fixed regulator.jpg
Dc Voltage regulator.JPG
Here is the schematic. Place the voltage regulator in a good heat sink.

With the LM350 I can change the voltage with the 5k variable resistor and at the same time I have the ammeter connected to make sure the amps will not raise 1.7A. (The LED is rated 1.8A but just to be on the safe side)

PLEASE NOTE :  I found a problem on the schematics, there shouldn't be connection between the anode of the 1n4001 and the negative of the 10uf.

ikoncani4 years ago
hello newtonn, thank you very much for this instructable.
however i found




i was wondering how to connect them with a pc fan and lcd(if needed)
AuriuX4 years ago
Can you send me all schematic in big format?
I cannot see in this little pic.
i need this one in big format:
My email: auriux69@hotmail.com
Thank you!
aekara AuriuX4 years ago
TheCiscoKid4 years ago

I built the schematic you have in the last picture for the LED. It seems to work find and the potentioeter seems to be doing its job bu the light is not bright at all even at the highest setting with the potentiometer. Do you know what may have gone wrong?
newtonn2 (author)  TheCiscoKid4 years ago

What is the power rate of the LED? and what is the power rate of the poser supply?

Did you use the LM350? or the LM317?
I have this led: http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=380286083290&ssPageName=STRK:MEWNX:IT#ht_3149wt_905

And i have a 20v 4.5 amp laptop charger.

and i used the lm350
newtonn2 (author)  TheCiscoKid4 years ago
Do you have an ammeter to check the amps going thru the led?

aekara4 years ago
could you just tell me how to power a 12v 0.15a fan , 9v 0.2 speakers , 12v 1a lcd monitor and a 13-18v 2a led

hinkjus325 years ago
Hi newtonn2, I was wonder what I would have to change in the schematic if i ran a 12v 2.0a fan. I decided to add a bigger fan because my heatsink isn't very large and I just have the 12v fan lying around. Would I be able to just use another 12v voltage regulator instead of the 5v one, or would there not be enough juice from the 20v input to run two 12v devices plus the LED? Forgive me if this is a dumb question but I dont remember much from school about circuits.
sbemail5 years ago
Hi, Thanks for this tutorial. So the resistors are just to tune the LM350, and any old power rating will work? I.e., is 1/4 watt okay for the 560Ohm, and should any 5K pot work? Thanks
macman115 years ago
would a 4.2 k ohm potentiometer work?
Hello newtonn2, thank you for the how to ;)

I've got one question:
The last schematic is the one that is corrected(the one with real pictures)?

Thank you
newtonn2 (author)  renavspainatal5 years ago
 The last schematic is correct, but it only shows how to connect the led. The other ones have a fault, but is already mention on the instuctable where the error is.

Thank you
SumitNovice5 years ago
Hi Newtonn2,
    Thanks a lot for the diagrams. Can you please upload the diagram images in a better resolution? Some text in the diagrams in not readable. When i try to download the diagrams and zoom they get blurry. Not sure if others are facing the same.

Also my request... Can we make a higher resolution projector. How about 1080p (or atleast 720p will also do  :)

Atleast if you proide the changes that we need to make and where we can get the parts it would be great!!!

Thanks again,
  realy appreciate
Rascafr5 years ago
Hello Newtonn2, I think as Tymenel that there is an error of wiring in your schematic. I looked in the "datasheet" of the LM350, and I deduced the following assembly from it ( by taking for exemple yours ). Could you say it to me if that will work ? 


( Excuse my bad english, I'm french ;)
newtonn2 (author)  Rascafr5 years ago
Thank you I found the problem on the schematic, is not what Tymenel suggested, there should be not connection between the anode of the 1n4001 and the negative of the 10uf.  If you get that of the diagram the rest is fine, is exactly as I'm using it just fine.
mbarela825 years ago
I really don't know anything about electronic or schematics but is there a way to wire it without the speakers? 
newtonn2 (author)  mbarela825 years ago
 Of course! I done the speaker so I don't have to connect the projector to anything else. You could do without the speakers.
how would that look on the schematic?
newtonn2 (author)  mbarela825 years ago
 I would change the schematic for you. Check the instructable in about 30min.
Ok, Thank you.
newtonn2 (author)  mbarela825 years ago
 OK, have a look at it know, there're schematics for all the options.... I hope!
Thank you very much.  I think this will work for me.
What is the 5k potentiometer for....to control the fan?
newtonn2 (author)  mbarela825 years ago
 It will control the voltage output for the LED to make sure it doesn't take more than 1.8A in my case.
Could I use a small 5k trim pot in place of the potentiometer?
newtonn2 (author)  mbarela825 years ago
That'll be not problem!
Hey, thanks for the schematics!
very helpfull
newtonn2 (author)  dragonzball5 years ago
 Not problem, I'm glad it helps.
tymenyel5 years ago
The 5k potentiometer is in a shortcirquit and your LED doesn't work on 1.2volt. I think the wire between 560 Ohm resistor and the annode of the 1N4001 should not be there.
The diode over the LM350 is a strange thing. I think that must be also a 1N4001 instead of a 1N4401.