LM1872 National Semiconductor, LM1872 Datasheet - Page 11

• Manufacturer Part Number: LM1872
• Description: Radio Control Receiver/Decoder
• Manufacturer: National Semiconductor

Applications
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-
R1
R2
R3
C1
C2
C3
C4
C5
C6
C7
C8
C9
C10
Motor decoupling
Sync timer R2
Mixer decoupling
LO bypass optional
LO tank C2
Ant input tank C3
V
Motor decoupling
Sync timer C6
Mixer decouple 0 01 F
AGC
IF bypass optional
V
(Continued)
BIAS
a
bypass 0 01 F
bypass
e
e
e
22 pF
t’
0 7 C6
t’
0 7 R2
SYNC
SYNC
e
s
24 pF
C10
72 MHz
s
R2
C6
C7
s
s
s
FIGURE 8 72 MHz Receiver Circuit
470k
0 5 F
72 MHz
s
0 1 F
0 1 F
11
C12
L1
T1
T2
T3
X1
D1
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
Ant input tank C12
LO Coil
Toko 10k type (KENC) 4T 0 2 H
L1 could be made a fixed coil if desired
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
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
Ant input transformer
Toko 10k type (KENC) 4T sec
2T pri of 0 2 H
5th overtone crystal parallel-mode 72 MHz
Electrostatic discharge (ESD) protection
72 MHz
e
160 pF
72 MHz
72 MHz
e
e
110
110
TL H 7912 – 15