possible 3$ boost circuit

[iccy]

I was messing around with the 1aaa rayovac penlight.
The exact same one found http://www.flashlightz.com/product.php?product=171701. Except I got mine from Wal-Mart for $3.88

The first one i bought i measured 78 mA. I removed the resistor and measured over 200mA.. I couldnt tell you how much because my multimeter only goes up to 200mA.
I accidentally broke it (lol), so I got another one and a new multimeter. Here are the results after removing the resistor.


Soldering where the resistor used to be.

I hooked up test leads

set multimeter to 10A, reading 400mA?

This would be an awesome laser 400mA with open can diode using only 1aaa!
I was thinking about making it into a laser, do you guys think its safe?

 

[jamilm9]

how many volts

 

[digital_blue]

Probably isn't a boost circuit. There should either be an inductor or a few capacitors(charge pump) and an boost converter chip.

 

[john_lawson]

yea what jamilm9 said it has to be above the required volt rating of the ld you are using

 

[FireMyLaser]

The output is probably very noisy, full of spikes and such. Maybe not ever regulated, so I'd say no. But maybe there's some room for improvements.

Probably isn't a boost circuit. There should either be an inductor or a few capacitors(charge pump) and an boost converter chip.

LEDs need more than 1.5V to work so it must be a boost driver.

 

[GooeyGus]

Voltage is the question here. A single AAA can easily put out 400mA, and probably a lot more, the problem is that it is only at 1.5VDC (although I dont think a LED will work at 1.5V... maybe?). Now if it can boost to 3-5VDC and still do 400mA, that will be impressive!

 

[iccy]

checking....
3.73v

 

[digital_blue]

Whoa, this might actually be a boost circuit. Could you get a picture of the other side?

 

[iccy]

sure one second

 

[iccy]

Both sides

 

[Ace82]

It looks regulated, and I believe a diode could run from 1.5V @400ma. Doesn't look like a boost circuit though.

 

[Benm]

It's entirely possible it is a boost circuit capable of delivering that much as long as the batteries supply plenty of input current.

One question is: is it regulated? What is the current at 1.0, 1.2 or 1.5 volts? And what is the current driving different voltages (try 1n400x diodes in series as dummies).

 

[jamilm9]

check ac too because led can take a lot of reverse voltage

 

[phoenix3200]

I believe I've seen ~3.5V boost chips that looked like the chip on the back, but I've yet to see a 5V boost chip in that form factor.  If someone does see one, please let me know.

Edit: There are ways to achieve more than 3.5 V out of a chip like that, but the output would not have good regulation.

 

[iccy]

Testing... Ill post results when done

     BATTERY                                    VOLTAGE AFTER CIRCUIT                  CURRENT AFTER CIRCUIT
Duracell at 1.60v                          -> in between 3.76v and 3.77v, briefly at 420mA and then receded to 400mA within a few seconds.

             

             

BATTERY VOLTAGE              VOLTAGE AFTER CIRCUIT    CURRENT AFTER CIRCUIT
Duracell rechargeable 1.45v      ->    3.71v,                                340mA

 

 

[positron]

you said you removed a resistor. maybe it is a voltage regulated boost circuit and the resistor was for current limiting.