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Sci.Electronics.Basics -> Need help checking my power calculations
There are 22 messages in this thread.
You are currently looking at messages 20 to 22.
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Author: kellDate: 10:46 05-09-06
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Gerald wrote:
> 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
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halogen
light
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pwm_____10R_____|| RFP30N06LE
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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.
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Author: John FieldsDate: 14:51 06-09-06
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On Sun, 03 Sep 2006 18:41:32 +0100, Eeyore
<rabbitsfriendsandrelations@REMOVETHIS.hotmail.com> wrote:
>
>
>John Fields wrote:
>
>> On Sat, 02 Sep 2006 21:54:00 +0100, Eeyore
>> <rabbitsfriendsandrelations@REMOVETHIS.hotmail.com> wrote:
>>
>> >Gerald wrote:
>> >
>> >> 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?
>> >
>> >Use a 2.5W bulb. The battery will last as long and it'll be a heck of a lot
>> >brighter !
>>
>> ---
>> Great idea!
>>
>> I'm going to change all of the 100 watt lamps in my house to 60
>> watts, since not only will they be brighter, It'll cost me less to
>> run them.
>>
>> Thanks ever so much!!!!
>
>Idiot.
---
LOL, It wasn't _I_ who suggested that a 2.5W lamp will burn brighter
than a 5W lamp, was it, dumbass?
--
John Fields
Professional Circuit Designer
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