Best and simple flashing circuits in one
With a pair of tiny, strategically placed LED turn signals, you can trust thieves that your vehicle is protected by a sophisticated alarm.
In addition, this circuit is so simple that even a beginner can step into its construction, without fear, to learn the joys of wiring in electronics.
have won by the sweat of our brow and to which we are attached. Also offers anti-theft (central home / car
radar detectors and various peri / volumes, thick bars on windows and doors, access controls, etc.) it explodes ... just like the price, whether to protect the vehicle or at home.
If you have already installed - in both - a security system with a burglar alarm, a small circuit that we present here offers an economical alternative to other possible devices to deter the thief that you choose for the victim! For example, a flashing of the LED
a video camera in dummy, you make it look like a fully functional professional video camera...and you've saved a lot of money. Of course, our system is purely deterrent, but that does not mean ineffective, because, after all (!), the thief prefers to attack a car or an apartment that does not introduce any doubts that camera insinuations can more flashing of the LED. Anyway, the car thief start, seeing the LED flash, forget it.
But in its simplicity, our small flashing circuit will find many other applications. If you want to raise a child of the electronic age 10-11, offer the material
needed for this assembly, a soldering iron with the stand and some basic sponge pliers (flat nose, side cutters and) you don't have and will ruin the joy of (the) learning to see the assembly under the benefit of your advice to superiors. And you learned something useful to structure his life...and why not shape his future work and focus his research accordingly.
Like sports, consumer electronics is a great way to find your bearings...and it's what young people miss the most. Especially if this tutorial goes through the game: it's a golden game you can achieve if you follow this article. Cardboard, scissors and glue is all you need for the decor. Halloween is a bit late, but for Christmas or Carnival, why not? But let's come to the electronics.
Figure 1: Wiring diagram of EN1683 flashing LEDs. This is an astable multivibrator with transistors, so the circuit goes
alternately from high/on state to low/off state. On the left pinouts of the transistor seen from below and of the LED seen from the front.
Figure 2: When the switching mechanism is engaged, two square signals are obtained, phase shifted by 180°. The transistors, in fact, are configured not to be simultaneously in the same state: when TR2 is saturated, its collector voltage Vce2 is therefore close to zero, TR1 is blocked and vice versa. The cycle repeats as long as the circuit is powered.
The electrical diagram:
The circuit in Figure 1 is an astable multivibrator transistor that intermittently drives two LEDs. This is the basic circuit of electronics: it is characterized by the fact that the collectors of the transistors on the two alternating states (high-low or on-off), in other words, the system periodically switches
from one state to another without receiving any external impulse (other than the original). The frequency of this
oscillation (and therefore the flashing) is determined by the resistive and capacitive values chosen. But
go into a bit of detail. NPN 2N3904 transistors used are simple capacitive coupling between the collector and the base: the collector of TR1 is connected by C2 to the base of
TR2, in turn, the collector of TR2 is connected by C3 to the base of TR1. These role electrolytics is to transmit the impulses present on the collector of a transistor to the base of the other, which determines a fast switching repeats indefinitely. In series with these capacitors were mounted through resistors R2 and R3 are necessary to lead or to lead to saturation the two semiconductors. As we chose the same values for C2-C3 and R2-R3,
the periodic oscillation of transistors between the two states is identical on-off and it has at the output a well-balanced square wave signal. To vary the duty cycle of the square signal and obtain different on-off times, choose different values of
resistance and capacitance. Remember, in any case, the astable multivibrator is usually
used to produce a square wave whose duty cycle is 50%, so the circuit does have a limited amount of asymmetry. Transistors can not take at the same time
same state when the conduit is t ie is saturated (state), the other not, ie blocks (state OFF). When powering the circuit, the saturation of one transistor and blocking the others are random and may depend on a disturbance or, more simply, the inevitable inaccuracy of the equality of the two parts of the circuit, in principle symmetrical ( indeed think that the components have a manufacturing tolerance and therefore the disparity between the actual values of the two components of the same face value
may be important).
Suppose that, because of such a disturbance, when the circuit is energized, the transistor TR2 is saturated. The collector voltage Vce of TR2 is close to zero and then turns DL2. During this time the voltage across C3 is transferred to the base of TR1, which is blocked. But it can't last
C3 is responsible exponentially through R2 when the voltage on the base of TR1 exceeds the threshold value (of these transistors is about 0.7 V), the transistor is saturated. Voltage Vce on the collector of TR1 becomes zero, DL1 turns on, the voltage on C2 and decreases when the voltage delivered on the base of TR2 exceeds the threshold value, the transistor is saturated again. The switching mechanism has started and we have two square waves 180 degrees out of phase, as shown in Figure 2. The cycle repeats until the circuit is energized. The oscillation frequency of the transistors is of course the blinking of the LED and is given by:
F = 1000: (1.38 x R x C)
where F is in Hz, R in kilohms and C in μF.
With the values we have chosen, this gives:
F = 1000: (1.38 x 56 x 10) = 1.29Hz
Since the duration in seconds of each flash is equal to the inverse of the frequency, we will have one flash approximately every:
1:1.29=0.77s
If you want to decrease the oscillation frequency and therefore the LED flashes slowly, you should rather act on the capacitive values, otherwise you risk corrupting the polarization of the transistors. If you want to get such oscillation frequency
0.2 Hz, which corresponds to one flash every 5 seconds, the ability to climb at C2 and C3 is calculated with the formula:
C = 1000: (1.38 x R x F)
where C is in μF, R in kilohm and F in Hz.
Which gives with the values taken
for example :
C = 1000: (1.38 x 56 x 0.2) = 64 μF.
This value is not standardized, mount two capacitors in parallel
33 uF electrolytic each, which will typically be 66 uF, tight tolerances. The resistors R1 and R4 connected in series between the collectors of the transistors and the cathodes of the diodes, are used to limit the current which flows through them and therefore their brightness. We chose 330 ohms which is good LED brightness whether you feed the V-mount 12 or through 9V. Don't choose
In any case, a lower value, because if you get a much higher luminosity, it would be for a
shortly and the LED would soon be destroyed by the Joule fusion junctions. The current must indeed be limited to 20 mA.
Note: To learn how to calculate the value of the limiting resistor, Evoia Course Learn Electronics From Scratch, Part One (available on CD from ELM Writing).
This circuit can be powered by a 9V battery (if requested) or by the 12 V cigarette lighter of the vehicle to be protected. C1, connected in parallel between the positive and negative supply serves as a filter.
En savoir plus sur ce texte sourceVous devez indiquer le texte source pour obtenir des informations supplémentaires
Envoyer des commentaires
Panneaux latéraux
Best and simple flashing circuits in one
With a pair of tiny, strategically placed LED turn signals, you can trust thieves that your vehicle is protected by a sophisticated alarm.
In addition, this circuit is so simple that even a beginner can step into its construction, without fear, to learn the joys of wiring in electronics.
have won by the sweat of our brow and to which we are attached. Also offers anti-theft (central home / car
radar detectors and various peri / volumes, thick bars on windows and doors, access controls, etc.) it explodes ... just like the price, whether to protect the vehicle or at home.
If you have already installed - in both - a security system with a burglar alarm, a small circuit that we present here offers an economical alternative to other possible devices to deter the thief that you choose for the victim! For example, a flashing of the LED
a video camera in dummy, you make it look like a fully functional professional video camera...and you've saved a lot of money. Of course, our system is purely deterrent, but that does not mean ineffective, because, after all (!), the thief prefers to attack a car or an apartment that does not introduce any doubts that camera insinuations can more flashing of the LED. Anyway, the car thief start, seeing the LED flash, forget it.
But in its simplicity, our small flashing circuit will find many other applications. If you want to raise a child of the electronic age 10-11, offer the material
needed for this assembly, a soldering iron with the stand and some basic sponge pliers (flat nose, side cutters and) you don't have and will ruin the joy of (the) learning to see the assembly under the benefit of your advice to superiors. And you learned something useful to structure his life...and why not shape his future work and focus his research accordingly.
Like sports, consumer electronics is a great way to find your bearings...and it's what young people miss the most. Especially if this tutorial goes through the game: it's a golden game you can achieve if you follow this article. Cardboard, scissors and glue is all you need for the decor. Halloween is a bit late, but for Christmas or Carnival, why not? But let's come to the electronics.
Figure 1: Wiring diagram of EN1683 flashing LEDs. This is an astable multivibrator with transistors, so the circuit goes
alternately from high/on state to low/off state. On the left pinouts of the transistor seen from below and of the LED seen from the front.
Figure 2: When the switching mechanism is engaged, two square signals are obtained, phase shifted by 180°. The transistors, in fact, are configured not to be simultaneously in the same state: when TR2 is saturated, its collector voltage Vce2 is therefore close to zero, TR1 is blocked and vice versa. The cycle repeats as long as the circuit is powered.
The electrical diagram:
The circuit in Figure 1 is an astable multivibrator transistor that intermittently drives two LEDs. This is the basic circuit of electronics: it is characterized by the fact that the collectors of the transistors on the two alternating states (high-low or on-off), in other words, the system periodically switches
from one state to another without receiving any external impulse (other than the original). The frequency of this
oscillation (and therefore the flashing) is determined by the resistive and capacitive values chosen. But
go into a bit of detail. NPN 2N3904 transistors used are simple capacitive coupling between the collector and the base: the collector of TR1 is connected by C2 to the base of
TR2, in turn, the collector of TR2 is connected by C3 to the base of TR1. These role electrolytics is to transmit the impulses present on the collector of a transistor to the base of the other, which determines a fast switching repeats indefinitely. In series with these capacitors were mounted through resistors R2 and R3 are necessary to lead or to lead to saturation the two semiconductors. As we chose the same values for C2-C3 and R2-R3,
the periodic oscillation of transistors between the two states is identical on-off and it has at the output a well-balanced square wave signal. To vary the duty cycle of the square signal and obtain different on-off times, choose different values of
resistance and capacitance. Remember, in any case, the astable multivibrator is usually
used to produce a square wave whose duty cycle is 50%, so the circuit does have a limited amount of asymmetry. Transistors can not take at the same time
same state when the conduit is t ie is saturated (state), the other not, ie blocks (state OFF). When powering the circuit, the saturation of one transistor and blocking the others are random and may depend on a disturbance or, more simply, the inevitable inaccuracy of the equality of the two parts of the circuit, in principle symmetrical ( indeed think that the components have a manufacturing tolerance and therefore the disparity between the actual values of the two components of the same face value
may be important).
Suppose that, because of such a disturbance, when the circuit is energized, the transistor TR2 is saturated. The collector voltage Vce of TR2 is close to zero and then turns DL2. During this time the voltage across C3 is transferred to the base of TR1, which is blocked. But it can't last
C3 is responsible exponentially through R2 when the voltage on the base of TR1 exceeds the threshold value (of these transistors is about 0.7 V), the transistor is saturated. Voltage Vce on the collector of TR1 becomes zero, DL1 turns on, the voltage on C2 and decreases when the voltage delivered on the base of TR2 exceeds the threshold value, the transistor is saturated again. The switching mechanism has started and we have two square waves 180 degrees out of phase, as shown in Figure 2. The cycle repeats until the circuit is energized. The oscillation frequency of the transistors is of course the blinking of the LED and is given by:
F = 1000: (1.38 x R x C)
where F is in Hz, R in kilohms and C in μF.
With the values we have chosen, this gives:
F = 1000: (1.38 x 56 x 10) = 1.29Hz
Since the duration in seconds of each flash is equal to the inverse of the frequency, we will have one flash approximately every:
1:1.29=0.77s
If you want to decrease the oscillation frequency and therefore the LED flashes slowly, you should rather act on the capacitive values, otherwise you risk corrupting the polarization of the transistors. If you want to get such oscillation frequency
0.2 Hz, which corresponds to one flash every 5 seconds, the ability to climb at C2 and C3 is calculated with the formula:
C = 1000: (1.38 x R x F)
where C is in μF, R in kilohm and F in Hz.
Which gives with the values taken
for example :
C = 1000: (1.38 x 56 x 0.2) = 64 μF.
This value is not standardized, mount two capacitors in parallel
33 uF electrolytic each, which will typically be 66 uF, tight tolerances. The resistors R1 and R4 connected in series between the collectors of the transistors and the cathodes of the diodes, are used to limit the current which flows through them and therefore their brightness. We chose 330 ohms which is good LED brightness whether you feed the V-mount 12 or through 9V. Don't choose
In any case, a lower value, because if you get a much higher luminosity, it would be for a
shortly and the LED would soon be destroyed by the Joule fusion junctions. The current must indeed be limited to 20 mA.
Note: To learn how to calculate the value of the limiting resistor, Evoia Course Learn Electronics From Scratch, Part One (available on CD from ELM Writing).
This circuit can be powered by a 9V battery (if requested) or by the 12 V cigarette lighter of the vehicle to be protected. C1, connected in parallel between the positive and negative supply serves as a filter.
En savoir plus sur ce texte sourceVous devez indiquer le texte source pour obtenir des informations supplémentaires
Envoyer des commentaires
Panneaux latéraux
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