We found this circuit in a 1980 documentation. The flasher uses 3 transistors in the configuration of an astable multivibrator that feeds 3 LEDs. Two transistors form the multivibrator and the third works in conjunction with the multivibrator, however with a delay given by capacitor C3. The basic frequency of the LEDs is given by capacitors C1, C2, and C3 which, according to the author, can have values between 33 uF and 100 uF. The recommended transistors are BC238, BC 237 or BC548, but any silicon NPN should work satisfactorily. The power for this circuit comes from 4 common batteries that together supply a voltage of 6 volts.
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