Monday, February 14, 2011

LED flasher circuit diagrams


Some 1.5 v LED flasher circuits are available on the internet and we like to present you four of them. The flasher circuits below operate on a single 1.5 volt battery.

lm3909 led flasher
The circuit on the upper uses the popular LM3909 LED flasher IC and requires only a timing capacitor and LED.

7404 led flasher
The top circuit, designed by Andre De-Guerin illustrates using a 100uF capacitor to double the battery voltage to obtain 3 volts for the LED. Two sections of a 74HC04 hex inverter are used as a squarewave oscillator that establishes the flash rate while a third section is used as a buffer that charges the capacitor in series with a 470 ohm resistor while the buffer output is at +1.5 volts. When the buffer output switches to ground (zero volts) the charged capacitor is placed in series with the LED and the battery which supplies enough voltage to illuminate the LED. The LED current is approximately 3 mA, so a high brightness LED is recommended.

2n transistors led flasher
The discrete 3 transistor circuit would need a resistor (about 5K) in series with the 1uF capacitor to widen the pulse width.

7414 led flasher


Read more:

No comments:

Post a Comment