Schematic Volt

This circuit alternately flashes 2 white LEDs, on a 3v supply and produces a really bright flash. The circuit produces a voltage above 5v if the LED isnt in circuit however the LED limits the voltage to its characteristic
voltage of three.2v to 3.6v.   The circuit takes concerning 2mA and is actually a voltage-doubler (voltage incrementer) arrangement.

The 1k charges the 100u and therefore the diode drops zero.6v to prevent the LED from setting out to illuminate on 3v. When a transistor conducts, the collector pulls the 100u down towards the 0v rail and therefore the negative of the electro is actually concerning 2v below the 0v rail. The LED sees 3v + 2v and illuminates terribly brightly when the voltage reaches about 3.4v.  All the energy within the electro is pumped into the LED to supply a really bright flash.

DUAL 1v5 WHITE LED FLASHER
This circuit alternately flashes 2 white LEDs, on a 1.5v supply and produces a really bright flash. The circuit
produces a voltage of concerning 25v when the LEDs dont seem to be connected, however the LEDs scale back this as they need a characteristic voltage-drop across them after they are illuminated. dont use a offer voltage above one.5v.

The circuit takes concerning 10mA. The transformer consists of thirty turns of terribly fine wire on a 1.6mm slug 6mm long, however any ferrite bead or slug will be used. the amount of turns isnt crucial. The 1n is very important and using the other worth or connecting it to the positive line can increase the provision current.
Using LEDs apart from white can alter the flash-rate considerably and each LEDs should be identical color.

The basic 2 LED astable multivibrator flasher built by Mary. She chose to use 2 different colored LEDs and the red LED is clear when unlit. It is quite bright when lit compared to the yellow LED despite the fact that it only draws 0.5 mA more. The bread boarded test schema was powered by a new 9 volt battery and was regulated by a L78L05 (in a TO-92 package as shown in the schematic). The 5 volt regulator was used to avoid exceeding the reverse breakdown voltage of the 2N3904. This topic will be discussed a little later on.

470 ohm current dropping resistors were chosen to keep the collector current draw less than 10 mA. The LEDS were bright enough to see well in dim lighting. You may change this resistor "R" value (lower R = brighter), but do not exceed the maximum current rating for the LED or transistor (this is more applicable to higher voltage multivibrators). You may also place 2 or more LEDs in series on each half of a multivibrator, however, the current dropping resistor may need to be reduced to maintain brightness. Consider using a power supply as opposed to battery power for your flashers.

To change the pulse (oscillation) frequency, you can change the base resistor or the timing capacitor values. For example, increasing the capacitor or the base resistor values will increase the time OFF per cycle and thus reduce the oscillation frequency. The oscillation frequency is 60 divided by the sum of the time OFF for each half of the multivibrator.  Do not feel you have to use the same timing capacitor for each 1/2 of the multivibrator. Multivibrators with different timing components on each 1/2 are termed asymmetrical.

Over time, some builders sent me emails that they could not get their multivibrator to run. I problem-solved with them and discovered many problems including bad parts, bread boarding errors, the oscillation frequency was too fast to observe, transistors were not saturated during their ON time and failure of the transistors due to excessive current or perhaps even reverse emitter-base breakdown.