Electronics Question, Voltage

PiKe

PiKe

PiKe

Caporegime
Joined
18 Oct 2002
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Location
Lake District
What options are there to drop 4.5v DC to 3v DC, can it be done with a resister?
 
PiKe said:
What options are there to drop 4.5v DC to 3v DC, can it be done with a resister?
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You mean potential difference :p

It can, but it depends if you want to increase the current? etc... What input and output do you want? Might be handy to know what power you're expecting to use too. :)

Resister? Transformer?
 
Rough guesstimates using P = I x V and V= I x R indicates that the pump needs 0.3A current so to drop 1.5V wee need a 5 ohm resistor. The resistor would need to have a 1W rating and would probably get warm.

That's all based on the "0.9" watt for the pump so could be a load of ******* . It would be best to use something like a LM317K as it will regulate the voltage irrespective of the load current. :)
 
I'd have thought a 3V pump would work ok with 4.5V personally, but if you want to be on the safe side then your best bet is to solder up a small regulator circuit. You can get the components from that high street electronics shop with the blue and red sign that musn't be mentioned on here. Should only be 3-4 components as it's just a 3-pin regulator and a couple of ballast resistors. They might even have a kit with a pre-etched pcb for the professional look :)
 
Easiest thing would be to get hold of 2 or 3 diodes, say a 1N5818, and put them in series with your 4.5v supply. The voltage drop accross the diodes will bring the supply down to approx 3v.
 
BullBoyShoes said:
Easiest thing would be to get hold of 2 or 3 diodes, say a 1N5818, and put them in series with your 4.5v supply. The voltage drop accross the diodes will bring the supply down to approx 3v.
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Ooo.. shiny LEDs ;)
 
BullBoyShoes said:
You could use a 3v zener, but this needs a series resistor, which you dont really want as it will limit the current to the pump, and possibly get warm. :)
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A zener diode doesn't need a resisitor if it is of a high enough current rating.

This would be the best option IMO.

Burnsy
 
BullBoyShoes said:
That would work except to my knowledge the lowest voltage zener you can get is 2.4v, hence the suggestion above
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But you don't want a 2.4v zener you want a 3v one which is most certainly avaliable.

Burnsy
 
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