Simple Basic Circuit

 Capacitor Charge: Define:              The capacitor is fully charged when the voltage of the power supply is equal to that at the capacitor terminals. Description: This circuit shows the step response of an RC network. The step is generated at t=0, when the switch is closed. The initial voltage of the capacitor can be set. V-I charateristic: Capacitor voltage: This formula is the result of a differential equation, as the current flowing in a capacitor is proportional to the derivative of the voltage applied to it. Capacitor current: This formula can be obtained again by solving a differential equation, or with the previous formula and then applying the Ohm's law. RC time constant: Also called tou , this constant gives the time required to charge the capacitor. In particular, after a time of 5RC the capacitor will reach the 99.3% of the input voltage step. while the 100% is an asymptotic value and will never be reached. So 5RC is usually the amo...

 BJT LED Control: Description:                       This circuit is used to control the current of an LED using a low power voltage source.  By exploiting the current amplification of the BJT. The voltage source will only need to provide the base current instead of the LED current, which is beta times smaller. Base current:                       The Vbe voltage of the transistor sets at 0.7V as it consists of a pn junction, thus the voltage drop across R1 can be easily found, and the base current consequently. Collector current:                           This current is the results of the amplification of a Beta factor of the base current and sets the current flowing into the LED. Max Collector current:                             ...

  LED Control: A constant current LED driver is an LED power supply that regulates the current flowing through an LED array so as to maintain a desired level of light output. Conventional power supplies provide an output that is regulated to deliver a constant voltage. Circuit Diagram: Description: This circuit is used to light up an LED with a precise amount of current. When an LED is forward biased, a precise voltage develops across it, called Vf , which is an intrinsic parameter of the device. The difference between Vcc and Vf gives the voltage drop across the resistor ., so you can find the current by dividing it by R. Question: 1)What is used to control LED current? Answer: Active control of LED forward current requires an active power supply. The topologies normally used for powering LEDs are the buck and the boost Switch Mode Power Supply (SMPS). Both actively control the current to the LED, and both benefit from the intelligence of a DSC. 2)Why do LED need constant current...

 Current Divider: Definition:                    Current Dividers are parallel circuits in which the source or supply current divides into a number of parallel paths. Circuit Diagram: Description:                       The current divider is used to split a current in two resistive branches. Unlike the voltage divider, it's not often used for a specific purpose in a circuit., but it's instead very common to use the formulas below while analyzing circuit, to know how current splits. Voltage drop: As the two resistors are in parallel, you can easily find the voltage drop across them by considering a single resistor which value is the parallel of the two, and then applying the Ohm's law. Current in R1 and R2: By knowing the voltage across the resistors (with the previous formula), you can find the current in R1 by dividing such voltage by R1 (the same applies for R2 Current Divider...

Voltage Divider: What is meant by a voltage divider? Definition:                    A resistor or series of resistors provided with taps at certain points and used to provide various potential differences from a single power source. Circuit Diagram: Description: As simple as useful. the voltage divider can be used to: -set a precise voltage reference; -make an R to V converter; -decrease the amplitude of a voltage signal.                     Current: Output Voltage: The output voltage is equal to the voltage drop across R2, which can be found by multiplying the current given by the previous formula with R2. Importance of a voltage divider: A voltage divider is one of the basic circuits used in electrical engineering. This is an important concept especially when more complex circuits are to be created. It allows engineers to analyze resistance and to optimize electronic devices. Thi...