2-transistor buck circuit

DickCappels

Joined Aug 21, 2008
7,687
Where is says "Q3" try reading it as "Q2" and I think it will make sense.

Alternatively, here is an excerpt from U.S. Patent 6,603,342 B. It is the same oscillator only the PNP and NPN have switched roles. The circuit lights a LED from a 1.5 volt battery. This circuit has been around for more than 50 years, yet the inventor was granted a patent in 2003. Maybe that's because there were no LEDs in 1960.

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Thread Starter

Frank@Frank

Joined Jul 24, 2021
4
Where is says "Q3" try reading it as "Q2" and I think it will make sense.

Alternatively, here is an excerpt from U.S. Patent 6,603,342 B. It is the same oscillator only the PNP and NPN have switched roles. The circuit lights a LED from a 1.5 volt battery. This circuit has been around for more than 50 years, yet the inventor was granted a patent in 2003. Maybe that's because there were no LEDs in 1960.

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Hi!
Say I want to design a 10-30V input voltage and output 9V 200mA, how should determine each components value and the switching frequency.
BTW, circuit can be patented?
 

MrChips

Joined Oct 2, 2009
24,134
This is your basic PNP-NPN relaxation oscillator. It should work. V1 can be almost any voltage 2-12V.
Change C1 for desired frequency.


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