The notion of "equivalent resistance", at its essence, means to be able to replace some set of resistors with a single resistor such that the rest of the circuit can't tell the difference. Imagine making a copy of the circuit and putting part of it in a box (or under a paper tent, or whatever else you might use to hide part of it). Now imagine that someone comes in and replaces what is in the box on one of the circuits with something else. You are then tasked with coming in and determining which circuit was changed, but you can't look in the box in any way. All of your work, be it measurements or modifications, have to be to the part of the circuit you can see. If it is impossible for you two tell the difference, then what is in the box on the modified circuit is truly equivalent to what is in the box on the original circuit.This is super basic. Thanks in advance.
Can the two resistors in the diagram have equivalent resistance or do you find a third value from those two that is the equivalent resistance?
The resistors can't be combined.Can the two resistors in the diagram have equivalent resistance
I thought they were parallels at best. But its neither? How do I make them parallel then?They are neither in series nor parallel, so I don’t know what you mean by equivalent resistance here.
I want 2 strings of LEDs in parallel and a power LED power on/off(not shown), not a single resistor to 2 parallels.If you mean can you use a single resistor and have the two strings of LEDs connected in parallel; that's not advisable.
Maybe the TS meant the equivalent resistance of the whole circuit? ie 5v / 30.5mA = 163.9Ω It makes as much sense as anything...
Yes, I was trying to solve the circuit resistance in parallel based on the circuit 5V and current.But you'd never put the LED strings in parallel...
Maybe the TS meant the equivalent resistance of the whole circuit? ie 5v / 30.5mA = 163.9Ω It makes as much sense as anything...
In order to be in parallel, they have to be connected such that the same voltage that appears across one must appear across the other. Not the same value of voltage, but the actual same voltage (sometimes referred to as the same symbolic voltage).I thought they were parallels at best. But its neither? How do I make them parallel then?
That's what you already have -- two strings of LEDs (with their current-limiting resistor) in parallel.I want 2 strings of LEDs in parallel and a power LED power on/off(not shown), not a single resistor to 2 parallels.
The reason behind selecting the parallel string is due to its orientation. I would use series if I could.
HiI thought they were parallels at best. But its neither? How do I make them parallel then?
I want 2 strings of LEDs in parallel and a power LED power on/off(not shown), not a single resistor to 2 parallels.
The reason behind selecting the parallel string is due to its orientation. I would use series if I could.
I think this is true in schematic in post #1 - right?Each string would require a separate amount of current from the voltage source.
Yes. Each string consists of two LED's and one resistor. Each will draw current separate from the other string.I think this is true in schematic in post #1 - right?
If I wanted to check the power of the circuit, say 1/4, 1/2 or higher watt resistor, do I check the power of the entire circuit or the individual components (using for ex. P =I^2 x R)?Yes. Each string consists of two LED's and one resistor. Each will draw current separate from the other string.
You can calculate the total current for one string using ohms law. Then, since the strings are identical and the parts are identical, just multiply the total current for one string by 2 to get the total current draw from the voltage source. If the LED's and resistors are different types and values, then the calculation is a little more complicated.
For a serial LED string you only need to calculate the power dissipation of the resistor.If I wanted to check the power of the circuit, say 1/4, 1/2 or higher watt resistor, do I check the power of the entire circuit or the individual components (using for ex. P =I^2 x R)?
How did you arrive at 50 ohms? Is this an arrived value or supplied value?R=50 ohms <---current limit resistor
I wanted to put this circuit out there and make sure I was constructing parallel strings correctly.In order to be in parallel, they have to be connected such that the same voltage that appears across one must appear across the other. Not the same value of voltage, but the actual same voltage (sometimes referred to as the same symbolic voltage).
That's what you already have -- two strings of LEDs (with their current-limiting resistor) in parallel.
What is it you are trying to achieve that the current circuit does not accomplish?
Each component of the series string (the resistor and each of the two LEDs) will have a voltage drop associated with it.How did you arrive at 50 ohms? Is this an arrived value or supplied value?
I've changed "R" to "Rlimit" for consistancy. Maybe that confused you a little.How did you arrive at 50 ohms? Is this an arrived value or supplied value?
by Jake Hertz
by Duane Benson