"Jerry G." wrote in message ...
You are right about these pointers. I have several cheap ones. After a lot
of use, they get weak, and become useless. Infact, the batteries are
lasting longer than the laser itself!

--

Greetings,

Jerry Greenberg GLG Technologies GLG
=========================================
WebPage http://www.zoom-one.com
Electronics http://www.zoom-one.com/electron.htm
=========================================


"Sam Goldwasser" wrote in message
...
"Jerry G." writes:

The small button batteries under the load of the laser diode, are most
likely having a greater voltage drop, than the higher capacity C
batteries.
The small button batteries, cannot have the capacity of the C batteries.

The breakover voltage where any LED device (laser diode) will function is
very tight. A small difference of the supply voltage in this region will
normally make a large difference in the output of the LED. Take care to
not
exceed any LED's maximum voltage rating. They can be easily damaged.

Both LEDs and laser diodes operate on current. So, the resistance
of the battery in conjunction with the internal resistor of the laser
pointer
control the current through the laser diode. Higher quality laser pointers
include an active current regulator which provides the current needed to
maintain the same light output via monitoring it in a feedback loop.
The pointers you find in Dollar stores only use a 50 ohm resistor. So,
the resistance of the batteries becomes significant.

Laser diodes are also exceedingly sensitive to overcurrent. Those
cheap pointers already tend to be unreliable and have limited life.
Increasing the brightness will shorten it further - possibly to 0.

--- sam | Sci.Electronics.Repair FAQ Home Page: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
+Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
| Mirror Site Info: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: The email address in this message header may no longer work. To
contact me, please use the feedback form on the S.E.R FAQ Web sites.

I have several laser pointers dating back as far as 1994, and have
never had one die, just need new batteries. They were gifts from
various functions I attended, but were not real cheap or real
expensive. The batteries can test ok for voltage using a simple
voltmeter, but you must test them under load so that you get a true
indication of their capacity. I typically use a 470 ohm resistor
across the battery, that puts a reasonable load on the battery and you
can sort thru a lot of ?? batteries in a short time t find whoich ones
are truly "good".

H. R. (Bob) Hofmann