SS's WIP GCP!

ShockSlayer · Post by **ShockSlayer** » Fri Jan 09, 2009 5:44 pm

Ah, I see!

SS

Mario · Post by **Mario** » Fri Jan 09, 2009 6:34 pm

Okay ppl, here you go. Note that this is different than the schematic I posted - I found there was a couple errors with it. Here is how you should build this:
EDIT: Look a little further down the page for another correction.

Note how the diode is facing. The stripe MUST be facing toward the battery or it will not work. Also, the LED resistor must be changed, since there is already a 10k resistor before it, but who knows, it might work. I need someone to test this for me! The red wires go to the + terminal of the battery, the black ones go to ground.

ShockSlayer · Post by **ShockSlayer** » Fri Jan 09, 2009 6:36 pm

Do I need to use the external 5v for the led if it can be powered from the source, since this is a 12v led?

Mario · Post by **Mario** » Fri Jan 09, 2009 6:42 pm

You connect both red wires straight to the battery. The problem with this design is, the 10k resistor is before the LED, so it acts a a current limiting resistor. You'd better use like a 3v LED.

ShockSlayer · Post by **ShockSlayer** » Fri Jan 09, 2009 6:47 pm

Mario wrote:You connect both red wires straight to the battery. The problem with this design is, the 10k resistor is before the LED, so it acts a a current limiting resistor. You'd better use like a 3v LED.

Okay, I'll try that. It looks like you used different resistors, I caught the 1k ohm one, what about the other? is that 5.6k?

Mario · Post by **Mario** » Fri Jan 09, 2009 6:50 pm

Well, I really don't know how much of a load the battery needs, but I know you need a resistor otherwise the battery is just going to be shorted all the time. (When the LED is off) The other one I think it should be 10k, but I'm not sure...

EDIT: Hold on a sec, I'm going to go test how low resistance you can go before it really is shorting the battery.

ShockSlayer · Post by **ShockSlayer** » Fri Jan 09, 2009 6:54 pm

Okay. I'll be right back, going to go rewire mine. I found a random transistor...

The way I am testing this, is, I have it connected to a plug, which can connect to a fully charged 11.1v battery, and that should have no led on. And then with the same plug connecting it to a 7.4v battery, and the led should be on.

SS

Mario · Post by **Mario** » Fri Jan 09, 2009 6:58 pm

Right, but make sure you have a switching transistor - either 2N3904, 2N2222, or 2N4401.

ShockSlayer · Post by **ShockSlayer** » Fri Jan 09, 2009 7:01 pm

Mario wrote:Right, but make sure you have a switching transistor - either 2N3904, 2N2222, or 2N4401.

Well, I don't know. I guess I got lucky, because: I finished my circuit(exact same as yours, except with a 10k Resistor, and hooked it up to my 11.1v, I got nuthin, and then my 7.4v, and the LED came on! YAYZ!

Thoughts?

SS

EDIT: the transistor says:

NEC
C1093
A829D

Not sure if that last digit is a d or an o

SS

Mario · Post by **Mario** » Fri Jan 09, 2009 7:18 pm

Guess it must be a switching transistor, then. You used a 10k for the current limiter? And your LED was a full brightness? I found that you should use a 1W 1k resistor for the current resistor and omit the LED resistor. So like this:

I was testing different resistor values and I tried a 33ohm one. I hooked it up to my 12v 2A power source and after a second decided it a good idea to grab it to feel if it was hot at all. Here's a tip: Don't, unless you enjoy 2nd degree burns.

ShockSlayer · Post by **ShockSlayer** » Fri Jan 09, 2009 7:23 pm

Ouch.

Yeah, it was a blue LED. Nice and bright. Lights up for a half second everytime I turn it on or off. Which rocks.

I can't wait till my battery is about to die!

SS

EDIT: I'm going to throw that picture into the sticky. Might be useful for others, who need status indicators.

Mario · Post by **Mario** » Fri Jan 09, 2009 7:29 pm

A huh huh huh!

Make sure you're monitoring that battery voltage with your multimeter when it gets low so you know at what battery voltage the LED lights up and how much longer you have after that. You could videotape it if you get tired of waiting.

In a perfect world, the LED should light up at 10.2 v, because you got two 5.1v diodes, however, they are made with slight tolerances, so the LED might actually go on at 10v or 9.9v, in which case you would add a small resistor (maybe 2.2k) before the diodes.

ShockSlayer · Post by **ShockSlayer** » Fri Jan 09, 2009 7:33 pm

Or, I could run my portable until it dies, and time how long it takes to die after the led comes on!

(which is what I'm doing right now) If it dies before LED turns on, then I need to add a resistor.

SS

Mario · Post by **Mario** » Fri Jan 09, 2009 7:38 pm

You've got it.

You may get bored of waiting, though, so that's why I said you should videotape it.

EDIT: Just saw your edit:
"EDIT: I'm going to throw that picture into the sticky. Might be useful for others, who need status indicators."

I'm also going to write a guide for that, so be looking for it.

ShockSlayer · Post by **ShockSlayer** » Fri Jan 09, 2009 7:46 pm

Mario wrote:You've got it. You may get bored of waiting, though, so that's why I said you should videotape it.

EDIT: Just saw your edit:
"EDIT: I'm going to throw that picture into the sticky. Might be useful for others, who need status indicators."

I'm also going to write a guide for that, so be looking for it.

Great!

I wont be bored if I'm actually USING the portable!

SS