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Subject: Re: Circuit for constant power source

Date: 01/31/00 at 10:16 AM
Posted by: Raymond E. Rogers
E-mail: rerogers@gte.net
Message Posted:

In Reply to: Re: Circuit for constant power source posted by Raymond E. Rogers on 01/31/00 at 8:43 AM:

: : Hello,

: : I am looking for a Circuit for constant pulse energy control switching modew power regulator using LM 317E with vco
: : Pulse width of the Bulb voltage/current out out will change inversely with the prevailing battery
: : voltage. Thus energy per pulse is constant. Reruired for a constant beam light intensity for a hand torch with 4 Zinc cardon or Penlite cells.
: : Bulbs rated 3.2/3.8/4.8/6 with 5 to 10% tolerance.

: Hi Rao
I remember the reason why constant (average) voltage is better than current. I believe the
resistance goes up with ageing so you will be running the bulb with more power at the later
part of it's life; which will shorten the life. If you want to do that, fine; but you should realize
the choices. Also you should check the technical sheets relating to the battery. With Ni-CAd
different load profiles affect the total energy you can extract. I don't know about the batteries
you are using but you should check to see what would be needed to extrract the maximum
amount of energy (over the total life) from the battery. I wouldn't expect that a 10kHz
pulse rate would be different from average but the manufacturer should be able to say for
sure.

Ray

: Ray


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