Need help checking my power calculations

[kell]

Hi,

I want to make a battery powered light, powered by a PIC.

I have a rechargable 6.6 volt battery, and a 5 watt halogen bulb.

Now, if I use a PIC and pulse the bulb at about 50% to get a dimmer
output, is it safe to guess that I would get about 6 hours light out
of this battery?

Also, at that power rating, can anyone suggest a transistor to use
that won't get too hot?

Thanks!
Gerald

Here's a possibility



battery
|
|
halogen
light
|
_|
|
pwm_____10R_____|| RFP30N06LE
|_
|
|
ground

http://www.fairchildsemi.com/ds/RF/RFP30N06LE.pdf

The rfp30n06le is a logic level mosfet,
so your 5 volts will turn it on.
The mosfet won't draw any current from your pic
or555.
The mosfet has about a twentieth of an ohm resistance,
so it won't get hot.

 

[John Fields]

Idiot.