App note (PDF) on automobile flashers from Texas Instruments:
This Application note presents the design of a low cost, flasher circuit with short circuit protection. The design incorporates the entire recommended design feature set for two wheeler flashers and includes low/high voltage operation, half load frequency doubling, and short circuit protection.
App note: Design of a low cost, 45W flasher with short circuit protection using LM2902 – [Link]
Marian Stofka writes:
Battery-operated equipment often will benefit from a power-on indicator. The indicator, however, can waste significant power. In situations where a low-duty-cycle blinking indicator provides an adequate indication of the power being turned on, the simple circuit described here should prove useful.
Low-duty-cycle LED flasher keeps power draw at 4 mW – [Link]
Ordinary LED flashers turn the LED on and off abruptly, which can get a little irritating after a while. The circuit shown here is more gentle on the eyes: the light intensity changes very slowly and sinusoidally, helping to generate a relaxed mood. The circuit shows a phase-shift oscillator with an adjustable current source at its output. The circuit is capable of driving two LEDs in series without affecting the current. The frequency is set by three RC networks, each of which consists of a 100 microF capacitor and a 22 kohm resistor. Operation is largely independent of supply voltage, and the average LED current is set at about 10 mA. The circuit adjusts the voltage across the emitter resistor so that it matches the base voltage of the first transistor (around 0.6 V). The phase shifting network gives rise to the oscillation around this average value. In the prototype of this circuit we used an ultra bright red LED.
Smooth Flasher circuit – [Link]
Dual color (4 line x 3 column) led, 12 white and 12 blue are intermittently switched controlled by two NPN transistors BC337. The speed and duty/cycle timing of lighting duration is determined by NE555 oscilator. The number of repetition of sequential lighting of each group of led is determined by 5-stage divide-by-10 Johnson counter with 10 decoded outputs and carry out bit (CD4017).
The intermittent lights from two group of led imitate the police car strobe lights.
The speed of switching off and on of led are continuously regulated by variable trimmer resistor.
24 LED Police Flasher – [Link]
Using the 4001 quad nor gate CMOS IC and a few other basic parts, build this simple alternating LED flasher.
How to make an alternating LED flasher – [Link]
I made this as a quick project I made to use a lot of the LEDs I recently got. It basically connects via a 555 8 pin IC and allows for adjusting the time between the flashings by changing the resistor or capacitor values. It provides for a cool looking effect in a dark room. Use your favorite color LEDs and enjoy!
41 LED Flasher Circuit using 555 IC – [Link]
This project is a flasher circuit able to turn on and off a bulb instead of a LED. It is based on the 555 timer IC is connected for astable multivibrator operation. It will create a flashing condition on the brake lights while the brake is pressed.
Automotive Brake Lights Flasher Project – [Link]
This is a novel flasher circuit using a single driver transistor that takes its flash-rate from a flashing LED. The flasher in the photo is 3mm. An ordinary LED will not work. The flash rate cannot be altered by the brightness of the high-bright white LED can be adjusted by altering the 1k resistor across the 100u electrolytic to 4k7 or 10k.
Super Bright Led Flasher – [Link]
This is a 1.2-volt single transistor flyback (Joule Thief) circuit that features a third coil. With it, flash duration and brightness is much enhanced, even with just a 10uF capacitor, as can be seen in the following schematic
1.2v LED Flasher – Joule thief – [Link]
LM3909 is a monolithic oscillator designed by National Semiconductor , to flash (LED) Light Emitting Diodes. Packaged in DIP 8 package LM3909 will operate between -25 and 75 degree . LM3909 require to work only few components and can be used in many light electrical applications. LM3909 can be used in applications like : warning indicators powered by 1.4V to 200V, toys and novelties . This chip seems not in production right now, do you know any replacement IC? leave comment.
The main features of LM3909 are :
- operation over one year from one C size flashlight cell
- bright, high current LED pulse
- few external components- low cost
- low voltage operation ( 1V to 5V )
- low current drain (under 0.5 mA )
- wide temperature range