Dave_H
Flashlight Enthusiast
I've been using these cheap flashlight "heads" that clip on to
a 9v battery. Pretty simple, switch, resistor and one 5mm LED.
They provide a small but respectable amount of light. They can
be fed by a supply of batteries taken from smoke detectors etc.
typically still at 7-8v, and run down to about 3.5v where they
become too dim to be much use. Even zinc-carbons can have
decent after-life (before proper disposal).
I found these at a discount store initially 3 for $5, then $2, but
were cleared out and have not seen them since, anywhere locally.
Conversion is simple but not very efficient. Can someone
point to a simple buck convertor circuit that would step down
say 4-10v to drive a LED at 10-15mA? Simplicity, efficiency,
and ease of part availability are important factors.
Dave
a 9v battery. Pretty simple, switch, resistor and one 5mm LED.
They provide a small but respectable amount of light. They can
be fed by a supply of batteries taken from smoke detectors etc.
typically still at 7-8v, and run down to about 3.5v where they
become too dim to be much use. Even zinc-carbons can have
decent after-life (before proper disposal).
I found these at a discount store initially 3 for $5, then $2, but
were cleared out and have not seen them since, anywhere locally.
Conversion is simple but not very efficient. Can someone
point to a simple buck convertor circuit that would step down
say 4-10v to drive a LED at 10-15mA? Simplicity, efficiency,
and ease of part availability are important factors.
Dave