Photo oscillation circuit

Abstract

Abstract PURPOSE:To enable to change the oscillation frequency by the intensity of light, by connecting a Zener diode between the negative electrode of power supply for the photo oscillation circuit consisting of NPN transistor Tr, PNP Tr and photo diode and the base of NPNTr. CONSTITUTION:When light is emitted to the photo diode 4, current flows, and when the voltage drop of the resistor 8 conneced between the emitter of NPNTr1 and the power supply negative electrode is greater than the Zener voltage of the Zener diode 5 connected between the base of Tr1 and the negative electrode of power supply, the collector current of Tr1 is interrupted. Thus, the voltage drop of the resistor 7 is avoided and the base potential of PNPTr2 is increased to the same potential as the positive electrode of power supply. The charge up voltage of the capacitor C6 lowers the emitter potential of Tr2 than the base potential to avoid Tr2 from being turned ON. When C6 finishes for discharge by the photo current of the diode 4, Tr2 turns on and Tr1 also turns on. The oscillating state is made by repeating this ON-OFF phenomenon. When the photo current of the diode 4 increases, the discharge time of C6 is shortened to change the oscillation frequency by the intensity of light.

Inventors

• 👤 Yukio Iitaka
• 👤 Toshiro Abe

Bibliographic Details