Although we intend that LED lighting is sudden (no light to light instantaneously), and the transistor will not work in active area, do not get it, though the transistor has a beta (current gain) very large, of order 300, the current through the base will be progressive. Each LED begins to illuminate when the desired voltage value reaches its maximum value later one volt. The entire circuit must be fed a steady supply of 12V.
'Lighting circuits'. Fig.1 Schematic fundamental vu meter. Design specifications are the following specifications: Supply voltage: 12 V Number of LED's used: 4 LED's. Operating mode: bar-shaped light. Maximum current LED lighting: 4 mA. Input voltage at which began to illuminate each LED:
1 - 2 V. 2 - 4 V. 3 - 6 V. 4 - 8 V.
Maximum input voltage: 12 V being the maximum stress for all LEDs are at their maximum brightness: 9 V. Development of power supply calculations transformer supplies 24 V ac. Initially we know the voltage and current to be provided at the output. For our case, the voltage will be 12V = Vz and the current will be calculated.
As in our circuit the number of lit LEDs will vary according to the input voltage, the current must provide power supply will also change, so that when there is tension in the driveway, no lights led, and the current drawn is 0 or nearly 0, and if on the contrary, the maximum input voltage, the current drawn is a maximum, and the collector current will flow basis over the four stages:
Lighting max = [Ic max + [(Vcc - 0.7) / 82K]] x 4 Imax = [(12 - 0.2-2) / 2700 + [(12 - 0.7) / 82K]] x 4 Imax = 15 mA. But to avoid problems in the operation of the circuit going to do the calculations by setting a maximum current of 30 mA, thus the circuit could be expanded with more LED's. How to get the required tension we start with an alternating voltage of 220 V 50 Hz, we need to transform, rectify, filter and stabilize the input voltage.
To transform, we use a voltage transformer, so we get to the exit of 24 V 50 Hz For a positive voltage only after the alternative, we use full-wave bridge rectifier D1, that to save space, is integrated. Its maximum current is 1 A.
Although we intend that LED lighting is sudden (no light to light instantaneously), and the transistor will not work in active area, do not get it, though the transistor has a beta (current gain) very large, of order 300, the current through the base will be progressive. Each LED begins to illuminate when the desired voltage value reaches its maximum value later one volt. The entire circuit must be fed a steady supply of 12V.
'Lighting circuits'. Fig.1 Schematic fundamental vu meter. Design specifications are the following specifications: Supply voltage: 12 V Number of LED's used: 4 LED's. Operating mode: bar-shaped light. Maximum current LED lighting: 4 mA. Input voltage at which began to illuminate each LED:
1 - 2 V. 2 - 4 V. 3 - 6 V. 4 - 8 V.
Maximum input voltage: 12 V being the maximum stress for all LEDs are at their maximum brightness: 9 V. Development of power supply calculations transformer supplies 24 V ac. Initially we know the voltage and current to be provided at the output. For our case, the voltage will be 12V = Vz and the current will be calculated.
As in our circuit the number of lit LEDs will vary according to the input voltage, the current must provide power supply will also change, so that when there is tension in the driveway, no lights led, and the current drawn is 0 or nearly 0, and if on the contrary, the maximum input voltage, the current drawn is a maximum, and the collector current will flow basis over the four stages:
Lighting max = [Ic max + [(Vcc - 0.7) / 82K]] x 4 Imax = [(12 - 0.2-2) / 2700 + [(12 - 0.7) / 82K]] x 4 Imax = 15 mA. But to avoid problems in the operation of the circuit going to do the calculations by setting a maximum current of 30 mA, thus the circuit could be expanded with more LED's. How to get the required tension we start with an alternating voltage of 220 V 50 Hz, we need to transform, rectify, filter and stabilize the input voltage.
To transform, we use a voltage transformer, so we get to the exit of 24 V 50 Hz For a positive voltage only after the alternative, we use full-wave bridge rectifier D1, that to save space, is integrated. Its maximum current is 1 A.