Onkyo A-SV610PRO, Service Manual

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PNP transistor used with Positive Power supply to Emitter and +ve biased.
[[Rectangular box shows DVM]]
I
n this kind of configuration the transistor is biased by Positive voltage. Do to the characteristic of the PNP
transistor reaction to a Positive supply at the emitter, the collector voltage will retain above the 600mv
minimum switching voltage. Even when the vb (base bias voltage) reaches near 0vdc, the lowest the
collector voltage will get is 650mv. Such configuration of a transistor is good where a circuit is expected to
operate at high frequency and need not idle below the switching voltage. It also provides none inverting
output. The transistor output is dependant of vb value, which can be trimmed by the resistor R3.
Such circuit is often used in video and like high frequency buffer circuit. It can also be used as sensory
circuit or low-level amplifier.