1.2V simple ‘555 A-Like’ circuit

Low voltage, low current possible solution for those without 555 timers in the spares box. The basic circuit is much like a Joule Thief, similar toroids, windings and transistor can be used. The Collector output of the transistor is intended to be used just like Pin 3 of a regular 555 timer chip. In the circuits shown: The first uses a 20 winds toroid, with a tap at the 10 winds point. Transistor is a 2N4401, capacitor is a 470uF 16V and the pot is 250K. 1.2V Ni-MH battery. The second uses a toroid actually taken from an old joule thief, which was bi-filar wound. Transistor on that one is a 2N3904, capacitor a 3.3uF 16V and pot is a 220K. 1V homemade Alum cell. The third uses a toroid intended for a Jeanna’s Light type of circuit, but altered to run with HV output on this circuit. It has 3 turns on the Primary and 12 turns on the secondary, transistor is a MPS222A, capacitor a 470uF 16V and pot is a 100K. 1.5V AAA battery. The values in the posted circuit will give a running circuit, but the components values are in no way critical. Joule thief’s are similarly very open designed and this can be viewed as a simple change to a joule thief. Have fun, use what you have 🙂

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