TM11-6130-381-14
Figure 4-2. Voltage at cathode of silicon-controlled rectifier.
resistor R6001, Zener diode CR6116, and RF filter
clipped sine wave voltage (B, fig. 6-2) that is in
phase with the charging path ac voltage. This
clipped sine wave is used as a positive voltage
R6122 and C61 14, and unijunction transistor
(UJT) Q6104. The UJT has three terminals: the
emitter, base (B1 ), and base (B2). Between B1 and
B2, the UJT has the characteristics of an ordinary
resistance. The emitter is reverse-biased until the
emitter -base voltage is greater than the emitter
peak voltage (Vp). The emitter peak voltage (Vp)
is dependent on the B 1 to B2 voltage (V b), and is
approximately equal to 0.6 Vbb. When the emitter
voltage (Ve) exceeds the emitter peak Voltage Vp),
emitter and B1 is very low, allowing emitter
current to flow. Voltage divider R6123 and R6124
Figure 4-3. Basic UJT miltivibrator circuit.
voltage.
the clipped sine wave voltage is used as the supply
circuit. Capacitor C6114 is charged to the potential
at resistor R6122 until the emitter voltage (Ve)
across R6003 is proportional to the current flowing
reaches the emitter peak Voltage (VP). At this
t h r o u g h the battery, a n d is compared to a
time, the UJT turns on and discharges C6114
reference voltage and amplified in differential
through RL O A D. When the emitter voltage falls
to approximately 2 volts, conduction ceases and
to capacitor C6114 in the multivibrator circuit,
the cycle is repeated.
4-3