How a torch is constructed
A torch is an indispensable tool at home and in industry. Wherever there is a lack of light, it will help you get the job done, find a problem, locate a fallen or rolled object. To repair a faulty lantern or improve it, you need to know its wiring diagram.
How a hand torch works
Building a hand torch is not complicated. It consists of a battery compartment and a compartment containing a transmitter and a reflector, as well as a switch.
This content has not changed since the invention of the pocket flashlight, although the component base has changed dramatically.
Diagram of a simple torch
Under current conditions, incandescent bulbs are largely being replaced by LEDs. They didn't hold up against the competition due to their lower efficiency and shorter lifespan. In portable luminaires, semiconductor light-emitting elements are also widely used. But it is not possible to simply replace a bulb with an LED (or an array of LEDs). You need a device that limits current through semiconductor elements. This is called a driver and is an electronic current regulator.
The downside of this circuit is the poor repairability of such a torch - a skilled technician and proper lab equipment would be needed to restore the electronic circuit.
The conductor could be a regular resistor which will limit the current and quench excessive voltage. But much of the power will be wasted in resistance. For a mains-powered lantern, this fact is not important, but for a battery-powered or battery-powered lantern, this disadvantage can be critical.
The headlamp is a popular model of LED flashlight. Such a flashlight allows you to completely free your hands and direct the light beam to the desired place by turning your head: following your gaze. It's convenient for repairing a car, walking in dark places, etc.
the control circuit (responsible for mode switching);
buffer amplifier;
a transistor switch to turn on the LED.
One of the variants of this device is where the control unit is made on a standard microcontroller (for example, ATtiny85), with a program to control the mode of the transmitter, the intermediate amplifier is an operational amplifier OPA335 , and an IRLR2905 field-effect transistor is used as a switch.
This circuit is inexpensive and reliable, but it has a technological drawback: you must program the controller before installation. Therefore, in mass production, a specialized chip FM2819 is used as the control unit (the abbreviated designation 819L can be applied to the case). This chip can turn the light-emitting element on and off and is programmed with four modes:
maximum brightness;
medium brightness;
minimum brightness;
strobe light (flashing light).
The modes are changed cyclically by briefly pressing the button. A long press on the button switches the lamp to SOS mode. It is not possible to modify the program (at least the data sheet does not mention such a possibility). The device does not require an intermediate amplifier, but it is not possible to connect very powerful LEDs directly to the output - there is a load limitation (and protection against load overflow).
Therefore, high power elements are connected by a switch. In most cases this is a field effect transistor that allows continuous high current operation in the drain circuit, such as Fairchild's FDS9435A or similar, which can be chosen from the parameters in the table specifications of the FDS9435A.
How a torch is constructed
A torch is an indispensable tool at home and in industry. Wherever there is a lack of light, it will help you get the job done, find a problem, locate a fallen or rolled object. To repair a faulty lantern or improve it, you need to know its wiring diagram.
How a hand torch works
Building a hand torch is not complicated. It consists of a battery compartment and a compartment containing a transmitter and a reflector, as well as a switch.
This content has not changed since the invention of the pocket flashlight, although the component base has changed dramatically.
Diagram of a simple torch
Under current conditions, incandescent bulbs are largely being replaced by LEDs. They didn't hold up against the competition due to their lower efficiency and shorter lifespan. In portable luminaires, semiconductor light-emitting elements are also widely used. But it is not possible to simply replace a bulb with an LED (or an array of LEDs). You need a device that limits current through semiconductor elements. This is called a driver and is an electronic current regulator.
The downside of this circuit is the poor repairability of such a torch - a skilled technician and proper lab equipment would be needed to restore the electronic circuit.
The conductor could be a regular resistor which will limit the current and quench excessive voltage. But much of the power will be wasted in resistance. For a mains-powered lantern, this fact is not important, but for a battery-powered or battery-powered lantern, this disadvantage can be critical.
The headlamp is a popular model of LED flashlight. Such a flashlight allows you to completely free your hands and direct the light beam to the desired place by turning your head: following your gaze. It's convenient for repairing a car, walking in dark places, etc.
the control circuit (responsible for mode switching);
buffer amplifier;
a transistor switch to turn on the LED.
One of the variants of this device is where the control unit is made on a standard microcontroller (for example, ATtiny85), with a program to control the mode of the transmitter, the intermediate amplifier is an operational amplifier OPA335 , and an IRLR2905 field-effect transistor is used as a switch.
This circuit is inexpensive and reliable, but it has a technological drawback: you must program the controller before installation. Therefore, in mass production, a specialized chip FM2819 is used as the control unit (the abbreviated designation 819L can be applied to the case). This chip can turn the light-emitting element on and off and is programmed with four modes:
maximum brightness;
medium brightness;
minimum brightness;
strobe light (flashing light).
The modes are changed cyclically by briefly pressing the button. A long press on the button switches the lamp to SOS mode. It is not possible to modify the program (at least the data sheet does not mention such a possibility). The device does not require an intermediate amplifier, but it is not possible to connect very powerful LEDs directly to the output - there is a load limitation (and protection against load overflow).
Therefore, high power elements are connected by a switch. In most cases this is a field effect transistor that allows continuous high current operation in the drain circuit, such as Fairchild's FDS9435A or similar, which can be chosen from the parameters in the table specifications of the FDS9435A.
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