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Will a voltage divider waste power?

ratstar

Aug 20, 2018
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just use a voltage divider, or a current divider. voltage dividers are better cause they dont waste electricity, but current dividers do.

or... just use a resistor...
 
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bertus

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Hello,

just use a voltage divider, or a current divider. voltage dividers are better cause they dont waste electricity, but current dividers do.

A voltage divider WILL waste power.

Ohm's_Law_Pie_chart.svg.png
Any resistor that drops a voltage will waste power.

Bertus
 

ratstar

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If you pick the right resistance it wont heat up as much, but it further makes it more efficient that less is actually even coming out of the battery with a voltage divider, due to the ratio of resistance. (one of the pathways just leads back to the battery again.)
 
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Audioguru

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A dead short is one "of the pathways just leads back to the battery again". It wastes ALL the battery's power.
A series resistance wastes power.
A series resistance and a resistance to ground (in a voltage divider) has both resistors wasting power.
A series resistor and a voltage divider produce very poor voltage regulation.
 

ratstar

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All I really meant was something basic, that the junction leading to negative/ground with the resistor, will take no current at all, it all goes down the short, and the voltage reduction transformation is 99% perfect, the rest stays in the battery fine and it develops less heat because of it.
150904529_1418803805134339_2143883750166940744_n.jpg



And if you add a bypass cap to it, you can reduce the resistance to 0, what goes into your device.
 

Audioguru

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When you short the resistor then there is no voltage divider and there is no load.
Without having a load then a bypass capacitor is not needed.
 

Audioguru

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A voltage divider does not have its output shorted like that.
Here is a real voltage divider and here is your shorted circuit:
 

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ratstar

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I mean to put the device on the shorted line. thats right isnt it?
You splice into it.
 

Audioguru

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Why can't you properly sketch and properly describe what you talk about?
Maybe this is what you mean:
 

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ratstar

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The resistance of the device cant be higher than r2, thats why I thought use a bypass capacitor, then the resistance can be higher than r2. But it will discharge along r2 as well as the load... so ive got issues with that maybe.
 

Audioguru

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If the load resistance cannot be higher than R2 then R2 will do nothing but waste power instead of regulating the reduced voltage.
A capacitor will not regulate the voltage but can filter it.
 

ratstar

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It still works, but R1 and R2 have to be high value resistors, higher than the load, so it reduces current and voltage, and the more resistive the load the more it wastes as it equalizes with the R2 resistor.

But I need to look at it further, there might be a way it can work! =)

Maybe if u add a spark gap separation, it could work, but ud need high voltage.... and erm... havent i reduced voltage... :)

trythis2.png


Yes its made a single pole filter, but its only dc going into it.
 
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Audioguru

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Why do you have a useless high voltage spark gap powered from expensive high voltage resistors that reduce the voltage?
What high voltage load do you have that uses an expensive high voltage capacitor parallel with it to filter away current pulses created by the spark gap?
How will you prevent the spark from causing radio, TV and communications interference?

60 years ago I made a blinking light chaser with a 90V battery and some neon light bulbs, each bulb with a series resistor and a capacitor to ground. the neon bulb was in parallel with the capacitor. The series resistor allowed the capacitor to charge slowly then when the 60V threshold voltage of the neon bulb was reached it conducted and lighted, discharging the capacitor then it would repeat as an oscillator. The neon bub produced no interference.
Today low voltage LEDs and logic ICs are used to make RC oscillators and sequencers.
 
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