LM1872

Manufacturer Part NumberLM1872
DescriptionRadio Control Receiver/Decoder
ManufacturerNational Semiconductor
LM1872 datasheet
 


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Applications
(Continued)
R1
Motor decoupling
t’
SYNC
R2
Sync timer R2
R2
e
0 7 C6
R3
Mixer decoupling
C1
LO bypass optional
C2
LO tank C2
22 pF
72 MHz
e
C3
Ant input tank C3
24 pF
e
C4
V
bypass
BIAS
C5
Motor decoupling
t’
SYNC
C6
Sync timer C6
C6
e
0 7 R2
C7
Mixer decouple 0 01 F
s
C8
AGC
C9
IF bypass optional
C10
V
a
bypass 0 01 F
C10
s
In a practical remote data link the transmitter could be bat-
tery operated and set up to transmit for brief intervals only in
order to save power The brief transmission could be used
to set or reset the digital output latches in the LM1872 and
or command new motor positions via the analog channels
After transmission the commands would be stored electri-
C12
Ant input tank C12
L1
LO Coil
470k
s
Toko 10k type (KENC) 4T 0 2 H
L1 could be made a fixed coil if desired
T1
455 kHz mixer transformer
Toko 10 EZC type (RMC-502182) Qu
Pin 1–2 82T pin 2–3 82T
Pin 1–3 164T pin 4–6 30T
72 MHz
T2
455 kHz IF transformer
Toko 10 EZC type (RMC-502503) Qu
Pin 1–2 82T pin 2–3 82T
Pin 1–3 164T pin 4–6 8T
0 5 F
s
T3
Ant input transformer
Toko 10k type (KENC) 4T sec
C7
0 1 F
s
2T pri of 0 2 H
X1
5th overtone crystal parallel-mode 72 MHz
D1
Electrostatic discharge (ESD) protection
0 1 F
s
FIGURE 8 72 MHz Receiver Circuit
cally in the case of the digital channels and mechanically in
the case of the analog channels
As a final note if the case of D1 is connected to the anode
rather than the cathode the circuit of Figure 9b should be
used at the input to maintain electromagnetic shielding
11
TL H 7912 – 15
160 pF
72 MHz
e
72 MHz
110
e
110
e
72 MHz