N08
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Hybrid Chips
Comparator
Q
+VS
Q
analog VB
+
analog VA
TTL out Q
VA
-
VB > V A
VB < V A
VB
VB
Q=1
Q=0
VA
-VS
t
Q
VB
VA
t
Zero crossing comparator
VB
+
-
Q
Schmitt trigger – TTL 7414
Q
Q
VIN
VIN
Q
VTL
VTH
VTH ≈ 1.7 V
VTL ≈ 0.9 V
VB
VTH
VTL
t
N08
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555 Timer
8 VCC
Threshold 6
5 Control
555 timer chip (556 dual, 558 quad)
VCC = 4.5V to 15V
supply current = 5 mA
output current = 200 mA max
2 Trigger
> 1/3 VCC
Trigger
Output
R
Discharge 7
Q
S
F/F
4 Reset
Q
3 Output
Q
1 GND
1
VC1

5V
5V
2/3 VCC
VCC
R1
8
Single Shot Pulse (monostable)
A low level trigger pulse below 1/3 VCC
applied at VIN deactivates the transistor that
otherwise shorts C1 to GND. The output then
goes high as C1 charges through R1. When the
voltage on C1 reaches 2/3 of VCC, the F/F
toggles and discharges C1 to GND and the
output goes low.
 = R 1 C1
4
3 VOUT
7
6
VIN
2
5
C1
1
0.01 F
VCC
100K
R1
8
4 STOP
7
3
R2
6
2
5
C1
1
0.01 F
VOUT
Multivibrator (astable)
This circuit will trigger itself to function as an
oscillator. C1 charges through R1+ R2 but
discharges only through R2. The voltage on C1
ranges between 1/3 to 2/3 of VCC. Frequency
of oscillation is independent of VCC.
 = 0.693 (R1+ R2) C1  = 0.693 R2 C1
f = 1.44 / (R1+ 2R2) C1
N08
STM 556 die
page 3 of 3