Page 22 - Shellie Suzana Binti Saad
P. 22
PHOTO TRANSISTOR
(OPERATIONAL CIRCUIT)
Operation depends on the biasing arrangement and
light frequency. In a forward-biased PN junction, the
increase in current is negligible.
Reverse-biased PN junction will increase the current
flow considerably and it effects the light intensity.
Therefore, reverse bias is the normal mode of
operation.
The physical base lead of the transistor can be left as
an open terminal, or it can be used to bias up to a
steady state level.
Thus, light stimulation causes a change in base
current, which in turn causes a bigger increase in
collector current and, the current gains a rather large
increase.
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