HP 5340A Service Manual

Model 5340A
Theory of Operation
4 - 23. Four - Line to Ten - Line Decoder 1820 - 021 4
4 - 24. The 1820 - 0214 decoder (Figure 4 - 9) consists of eight inverters and 10 four - input NAND
gates. As shown in the truth table, the unit accepts BCD inputs and provides the equivalent
decimal output.
The activiated output will be
a logic low. For example, if the BCD input is
DCBA = 0111, then the decimal 7 output will go low and all others will be high.
Figure 4
- 9. Four - Line to Ten - Line Decoder 1820 - 0214
r
INPUTS OUTPUTS
vcc ITtf-TT ‘9 : i
0 12 3 4 5 6,GND
OUTPUTS
1820 - 0214
(POSITIVE LOGIC)
FOUR - LINE TO TEN - LINE DECODER
TRUTH TABLE
BCD INPUT DECIMAL OUTPUT
4 - 25. Operational Amplifier 1820 - 0216
4 - 26.
Figure
4 - 10 shows the diagram for the operational amplifier. Operational amplifiers are
so named because they perform a mathematical operation in a circuit. The type of operation is
determined by the feedback network. In the 5340A, this IC is used in a dc stabilizing feedback
network on A17.
Figure 4
- 10. Operational Amplifier 1820 - 0216
1
.
NOTE: Pin 4 connected to case
I
4 - 27. Monostable Multiviprator 1820 - 0261
4 - 27. This multivibrator (Fi$uie 4 - 11) is stable in one state only; i.e., when not triggered, Q is
low and
Q is high. Triggerink is dc from either positive or negative - going inputs and is not
directly related to the
transidion time of the input pulse. A1 and A2 are negative - edge - triggered
logic inputs and will trigger the one
- shot when either or both go low provided that B is high. B is
the positive Schmitt trigger input that triggers the
one-sh$ when B goes high with either A1 or
A2 low. When the monostable triggers,
Q goes high and Q goes low for a period determined by
4
- 8

HP 5340A Specifications

General

Brand	HP
Model	5340A
Category	Cash Counter
Language	English