hello guys,
my question is this : if a resistor contribute in a voltage drop and voltage at output end of resistor will be lower than the input voltage, why use a voltage regulator then to regulate the voltage and not resistors ?
firashelou:
hello guys,
my question is this : if a resistor contribute in a voltage drop and voltage at output end of resistor will be lower than the input current, why use a voltage regulator then to regulate the voltage and not resistors ?
Because the voltage drop across the resistor will increase with increasing current demand by the output load attached to the resistor, thus the load will see variable voltage if the load is varying it's current demand (it's resistance). A regulator will maintain a constant output voltage even when subjected to variable load current demand (load resistance), within the current rating of the regulator of course.
Lefty
You still don't have a grasp at electronics.
a resistor contribute in a voltage drop and voltage at output end of resistor will be lower than the input current
This is a line of text that is simply incorrect.
Where did that word current come from ?
It just popped up at the end of that line.
You are comparing "input current" to voltage regulation, which shows your total confusion on what's what in electronics.
As this is basic stuff you really need to get a grip on this before you go on with your experiments.
A resistor limits current,
The result is a voltage drop over that resistor.
A resistor doesn't have a voltage entry and a voltage exit like what you have in mind.
Because a resistor is a current limiter (see the difference from current regulator ?) , you could use such resistor for your goal.
But only if the other values are fixed.
These values are voltage and the other resistance in the circuit.
You would create the well known voltage divider that way, and you would measure a fixed voltage at what you just called "output end".
MAS3:
This is a line of text that is simply incorrect.
Where did that word current come from ?
i'm sorry about this mistake, i meant voltage, actually i didn't knew how to explain what i mean at the end so i simply said input voltage to refer to the circuit main voltage coming from the power supply
retrolefty:
Because the voltage drop across the resistor will increase with increasing current demand by the output load attached to the resistor, thus the load will see variable voltage if the load is varying it's current demand (it's resistance). A regulator will maintain a constant output voltage even when subjected to variable load current demand (load resistance), within the current rating of the regulator of course.Lefty
so you mean the voltage will be up to reach the voltage needed by the component ? but we put resistors to decrease the current to reach the current needed by the component !
The resistor has a basic equation, Vin-Vout = I R
The regulator has a completely different equation, Vo=constant. (within reason).
If you use a resistor in place of a regulator you get Vout = Vin - I R, which is not
constant (unless the input voltage and load current are both constant, which they
usually are not if you need a regulator)
ok thank you