Flashing LED with a Transistor Simple and Inexpensive
- Often we need to put in a circuit a small Flasher, a warning to any, or even a simulator alarm or security camera connected. But making a common circuit flashes, or two transistors using LM555, Besides being expensive, the project more expensive and increases their physical size. Here in this article we will see a LED flasher that uses only one transistor and 3 passive components. But first let's see the common Flasher.
How to Make an LED flasher
Make a flashing LED is easy, depending on your needs, you can use a integrated circuit timer 555 for flasher LED. You can also use a common circuit with two transistors in the circuit as seen below. This circuit is called astable multivibratorwhich is a circuit that has no stable state.List of material
Q1 e Q2 – Transistors BC548 or any general purpose NPN transistor
LED1 e LED2 – LEDs comuns – Any color
R1 e R4Resistor 470 ohms 1/8 Watts
R2 e R3Resistores 22 kohms 1/8 Watts C1 e C2
Electrolytic Capacitors 10 a 100 uF por 16 Volts or more.
Flashing LED with Transistor
Cut to the chase, our flasher LED with a transistor that is simple to build and very cheap. Although it appears something supernatural, the operation is simple. A resistor 1k ohm loads slowly electrolytic capacitor 220 uF X 25 Volts until the voltage becomes high enough to release the base-emitter junction of transistor 2N2222.
Flasher with a transistor set up and worked perfectly
At this point the transistor leads quickly, and partially download the capacitor 470uf for LED, which light up quickly. The resistor 100 Ohm only works as a current limiter LED. This simple and functional LED flasher is very interesting, the diagram below this setting he worked with a tension between 10 Volts a 13 Volts, and to the extent that tensão subia range of flashes decreased.
The transistor used was a 2N2222 which is an NPN, he had a very stable behavior, seems to work reliably in this circuit, but other transistors can be tested is clear thatFew will work. Unlike the version with two transistors that can use any NPN type transistors, since this version presented here transistor requires some special qualities that we will see below.
Tunnel Effect
We called the Tunnel effect, no case, the tunnel effect, “in quantum mechanics, consists in the event of a particle through a region where the potential energy is larger than its total energy – this barrier is insurmountable in classical mechanics, because the kinetic energy of the particle would be negative in the region” [Wiki]
So it is with a tunnel diode , which is a type of semiconductor that can operate very quickly, Microwave frequency, made possible by using so-called quantum mechanical tunnel effect. This means that there are few transistors that have this characteristic tunnel diode, the most common and easiest to find is really the 2N2222.
Test flasher circuit with LED with a transistor
See the video that the circuit flasher with LED and a transistor works perfectly.
http://blog.novaeletronica.com.br/en/pisca-pisca-led-transistor-simples-e-barato/
