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5 votes

How does this simple circuit work if the diodes are replaced by LEDs?

Short answer: as shown, this won't work hardly at all with LEDs swapped in. Why? LEDs have a much higher forward voltage drop (Vf) than normal diodes, somewhere between 1.2 and 3.5V depending on ...
hacktastical's user avatar
5 votes
Accepted

Why does the reciprocal of sum of reciprocals relationship appear commonly?

Resistance isn't the only descriptor of the behaviour of a resistor. That same behaviour could be represented by the reciprocal of resistance, which is conductance (usually called \$G\$): $$ G = \frac{...
Simon Fitch's user avatar
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3 votes
Accepted

IR Blaster Resistor Calculation for IR LED (breaking ohm's law?)

The simple answer is, the LED isn't driven with 254mA DC, it's driven with pulses of 254mA. And as the LED datasheet says, it can handle pulses of 1A, when individual ulses are less than 100us, and ...
Justme's user avatar
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2 votes

IR Blaster Resistor Calculation for IR LED (breaking ohm's law?)

The LED isn't driven continuously. It is driven with a 'carrier' (typically 38 kHz) that is lower duty cycle. The LED can tolerate higher currents when pulsed this way. 250 mA peak isn't unreasonable ...
hacktastical's user avatar
2 votes

RC circuit equation why have negative sign

According to the conservation of energy $$ P_{in}+P_{out}=0 $$ According to passive sign convention power leaving a circuit is considered positive, while power entering a circuit is considered ...
RussellH's user avatar
  • 17k
1 vote

RC circuit equation why have negative sign

They should have drawn the current direction. These equations match the drawing below. These are the definitions of a capacitor and resistor, current flows into the positive end of the voltage. \$I = ...
Mattman944's user avatar
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1 vote

Why does the reciprocal of sum of reciprocals relationship appear commonly?

It simply means that the unit you're using for this measurement is the reciprocal of the quantity that you're actually adding. When you put two resistors in series, you're literally adding more ...
hobbs's user avatar
  • 7,647
1 vote

Why does the reciprocal of sum of reciprocals relationship appear commonly?

It appears in many contexts, as it's the sum of the harmonic mean of the elements, one of the ways of finding the "most normal value" of a set of values. Typically it's used for rates, such ...
jonathanjo's user avatar
1 vote

How does this simple circuit work if the diodes are replaced by LEDs?

As already mentioned the drop over a LED is too high. Also the current is very limited. Schottkys support much higher currents. This is how I would do it (for a low power application):
S_G's user avatar
  • 624
1 vote

Why does a 230V 16A socket supply only the needed current to loads?

If I connect a 150W laptop charger to a socket that supplies at home 16A 230V, it will only draw the necessary amperage needed for the laptop charger at 230V. Why? The definition of electrical power ...
Fabio Barone's user avatar
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1 vote

Frequency compensation circuit

Your circuit is a high pass filter. The time constant of the circuit can be found by looking at the circuit from the capacitor’s point of view. The capacitor sees R an Rc in parallel. The time ...
user69795's user avatar
  • 1,600
1 vote

What should my resistor wattage be to run a LED on 240VAC?

I actually found this exact thing in an old kettle I pulled apart they are using a 46 kΩ resistor in series with a standard blue LED, in series with a diode the resistor looks about 8 W capacity, ...
Code Warrior's user avatar

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