The Baron
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| posted on 31/7/07 at 07:36 PM |
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Dumb Question on Reistors
I have acquired a pulse generator, but it only requires a 5v input, how do I calculate how to get from a 12v supply down to 5v?
Cheers,
The Baron
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BenB
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| posted on 31/7/07 at 07:42 PM |
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I'd use a voltage generator as it control the voltage independant of current drawn.
If the current drawn is constant (unlikely but hey) then you can work it out using
R= V/I
12-5=7V, R= 7V/amps
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trikerneil
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| posted on 31/7/07 at 07:57 PM |
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How about a 7805? I have used them with some success.
WIKI ARTICLE
ACE Cafe - Just say No.
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RazMan
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| posted on 31/7/07 at 09:12 PM |
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DC-DC converter?
Cheers,
Raz
When thinking outside the box doesn't work any more, it's time to build a new box
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Macbeast
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| posted on 1/8/07 at 05:20 AM |
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As above - I'd probably use a 7805 voltage regulator.
Everything depends on how much current your pulse generator takes. A 7805 has max current of 1 Amp. There are others with higher current ratings. 1A
and 7 volts drop is 7 Watts so you would need to put it on a heatsink..
A simple resistor would only work if the current drawn were constant and the supply were a constant 12V. If the 12V is from the car supply, it's
going to vary. Also, a 7805 is going to be cheaper than a 7W resistor.
To be able to help, we need to know what the pulse generator is/does and what current it takes.
Hope that helps - not a lot probably 
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