Ramsey Electronics RXD433 User Manual
WIRELESS RF LINK
RECEIVER/DECODER
MODULE
Ramsey Electronics Model No. RXD433
Need a data transmitter or receiver for your remote wireless
application? These compact units are perfect for any project;
car alarms, door openers, home security, you name it!
• SAW Resonators for high stability – no drift!
• Compact size with low current demand.
• 433 MHz license free band.
• Sensitive superhet receiver with RF LNA.
• Automatic tuning – no manual adjustments.
• Operates on 5 volts DC.
RXD-433 • 1
RAMSEY WIRELESS RF LINKS
• TXE433 or 916 Transmitter & Encoder Module
• RXD916 Data Receiver& Decoder
• RX433 or 916 Data Receiver
• TX433 or 916 Data Transmitter
RAMSEY TRANSMITTER KITS
• FM10A, 25B FM Stereo Transmitters
• TV6 Television Transmitter
• “Cube” TV Transmitters
RAMSEY RECEIVER KITS
• FR1 FM Broadcast Receiver
• AR1 Aircraft Band Receiver
• SR2 Short-wave Receiver
• AA7 Active Antenna
• SC1 Short-wave Converter
• LC1 Capacitance/ Inductance Meter
RAMSEY AMATEUR RADIO KITS
• CPO3 Code Practice Oscillator
• DDF1 Doppler Direction Finder
• HR Series HF All Mode Receivers
• QRP Series HF CW Transmitters
• CW700 Micro Memory CW Keyer
• QRP Power Amplifiers
RAMSEY MINI-KITS
Many other kits are available for hobby, school, Scouts and just plain FUN. New
kits are always under development. Write or call for our free Ramsey catalog.
RXD433 WIRELESS RECEIVER/DECODER INSTRUCTION MANUAL
Ramsey Electronics publication No. MRXD433 Revision 1.1
First printing: July 1999
COPYRIGHT 1996 by Ramsey Electronics, Inc. 590 Fishers Station Drive, Victor, New York
14564. All rights reserved. No portion of this publication may be copied or duplicated without the
written permission of Ramsey Electronics, Inc. Printed in the United States of America.
RXD-433 • 2
THE RXD433
This wireless RF receiver/decoder has a 4 bit data output that will match the
data sent by the encoder, TXE433. The output is CMOS compatible when
the unit is run on +5 volts.
The demod bandwidth is selectable by the placement of jumpers on the
circuit board. The table on the schematic shows jumper positions for
different bandwidths. Narrower bandwidths will give slightly better range at
the expense of more limited constraints on battery voltage tolerance over
time and more limited operating temperature range. For most applications,
the 4800 Hz setting will be best.
The “decoder address select” allows you to use one transmitter to control
different receivers by giving each receiver a unique address. The decoder
chip has internal pull-up resistors making it a simple matter of grounding the
address select pins to match the grounded pins on the transmitter/encoder.
These outputs are also CMOS compatible when run on +5 volts.
The receiver/decoder unit additionally has a “data valid” output. This output
goes high when the “decoder address select” matches the encoder’s
address select. This is convenient place to connect a “data valid” LED
indicator to show at a glance when the receiver is decoding. The schematic
below shows how such an LED can be connected.
ANTENNA CONSIDERATIONS:
The simplest antenna consists of a piece of wire approximately 6 to 7 inches
long. If you desire more range you can try a ground plane antenna or a
Yagi such as the Ramsey 4004 model. The antenna should be tuned for the
433 MHz band for best operation.
RXD-433 • 3
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