Ramsey Electronics RR1 User Manual

Ramsey Electronics Model No. RR1

Have you ever been so frustrated with the range of your remote
that you go to the extreme of rearranging your entertainment
room just to make it work? Tired of having to bounce your IR
remote off of ceilings and walls? Do you want to run your
system from another room? Here is the answer to your prayers!
Extend the range of your remote controls as far as you need;
it’s only limited by the length of wire you use!

• IR receiver module with sensitive element can receive your

remote control up to 36 feet away before re-broadcasting it.

• The RR1 reconstitutes the receive signal using a PIC micro

controller, restores noisy or weak signals, and then re-broadcasts
the IR remote signals to your components via a long wire (tested
over 500 feet!) to a high-efficiency IR LED.

• Extend the range of your remote control around corners or down

floors by running a wire to an IR LED in front of the components
you wish to control.

• Works with almost any remote control (38 kHz carrier), does not

need to be programmed.

• Will operate from 8V to 16V AC or DC. Use our AC125 wall adapter

for long operation.

• LED indicator lets you know when you are receiving an IR signal

or not.

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RAMSEY TRANSMITTER KITS

• FM100B Professional FM Stereo Transmitter

• FM25B Synthesized Stereo FM Transmitter

• MR6 Model Rocket Tracking Transmitter

• TV6 Television Transmitter

• RR1 Wired Remote Repeated

• RRW1 Wireless Remote Repeater

RAMSEY RECEIVER KITS

• FR1 FM Broadcast Receiver

• AR1 Aircraft Band Receiver

• SR2 Shortwave Receiver

• SC1 Shortwave Converter

RAMSEY HOBBY KITS

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• SS70A Speech Scrambler

• BS1 “Bullshooter” Digital Voice Storage Unit

• AVS10 Automatic Sequential Video Switcher

• WCT20 Cable Wizard Cable Tracer

• ECG1 Electrocardiogram Heart Monitor

• LABC1 Lead Acid Battery Charger

• LC1 Inductance-Capacitance Meter

RAMSEY AMATEUR RADIO KITS

• DDF1 Doppler Direction Finder

• HR Series HF All Mode Receivers

• QRP Series HF CW Transmitters

• CW7 CW Keyer

• CPO3 Code Practice Oscillator

• 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.

RR1 KIT INSTRUCTION MANUAL

Ramsey Electronics publication No. MRR1 Rev 1.1

First printing: January 2002 MRW

COPYRIGHT 2002 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.

RR1 • 2

Ramsey Publication No. MR R1

Price $5.00

KIT ASSEMBLY

AND INSTRUCTION MANUAL FOR

RR1 REMOTE REPEATER

KIT

TABLE OF CONTENTS

Introduction ...........................................4

Theory of Operation ..............................5

Learn As You Build Strategy .................7

Parts List ...............................................9

Assembly Instructions .........................10

Testing the RR1 ..................................13

Using your RR1 ...................................14

Troubleshooting Guide ........................15

RR1 Schematic ...................................16

RR1 Parts Layout ................................17

Specifications ......................................18

Warranty .............................................. 19

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RAMSEY ELECTRONICS, INC.
RAMSEY ELECTRONICS, INC.

590 Fishers Station Drive

793 Canning Parkway

Victor, New York 14564
Victor, New York 14564

Phone [phone]
Phone [phone]

Fax [phone]
Fax [phone]

www.ramseykits.com

RR1 INTRODUCTION

Welcome to the RR1 kit (and if you don’t have the time, the wired and tested
version). Let’s take a moment to help you understand the basic workings of IR
remote controls and how the RR1 works. This will better help you understand
what you are about to build. As simple as it may look, the RR1 is one of the
best remote repeaters money can buy thanks to some specialized technology
we have added to restore normally unusable signals. We will get more into that
in the circuit description section.

The RR1 has multiple uses. A common application is to extend the normal
range of your remote control by receiving your remote’s signal and then re­broadcasting it a distance away via a wired IR element. Many stereo
component manufacturers skimp on the IR receiver sections of their equipment
so the range of the remote is very poor. Have you ever thrown your remote at
the power switch because the darn thing wouldn't work from across the room?!.
This kit helps to surmount that very problem. Another common use is to control
your unsightly stereo components that are hidden within a cabinet while you’re
entertaining. The unit allows your remote to control these items while they are
tucked away inside of a cabinet (or even locked away for security reasons) with
only the RR1 exposed so it can relay the information!

To use my house as an example, the stereo components are positioned
behind the couch and it is very cumbersome to have to reach way up with the
remote and beam it backwards in order to control them. Half the time it doesn’t
work even work for me because the batteries keep popping out of the remote (I
lost the remote’s back plate a long time ago in one of the many apartments I’ve
rented in the past, but that’s another story)! I don’t want to have to re-arrange
the room (that is the Wife won’t let me!) just so the remote will work better.
Instead I use the RR1 in front of the couch someplace and have it relay the
signal back to the equipment for me.

To increase the effectiveness of this kit, we take advantage of a high­sensitivity IR receiver element which claims on its specification sheet to work
up to 36 feet (11 meters) away from the remote control (that’s about 30 feet
further than my VCR remote works!). Now I can truly atrophy on the couch
when my favorite program comes on and feel the pounds start packing on!
“Hey… another bag of chips when you get a chance Honey!!”

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RR1 THEORY OF OPERATION

The RR1 may look simple but there is actually quite a lot being done inside
each one of the parts. Many individual components are packed inside of the
IR receiver part (U2) itself; so many in fact that if it was built up with discrete
components, it would never fit in this little kit case. Inside of the part there is
an IR detector diode, amplifier, AGC circuit, bandpass filter, a peak-hold cir­cuit, an integrator, comparators, and an output amplifier. Heck, the part is a kit
in itself! Just be glad it’s all in one nice module and ready to go.

IR remote controls send out their data on a 38 kHz carrier much like the way
your FM radio does. By modulating the carrier signal with the data you want to
send, it is possible to increase the range of the transmission and decrease in­terference from other IR sources like ambient light (the sun pumps out lots of
IR!!!). The modulation style used with remotes is called OOK (on off keying).
In a nut shell, OOK modulation means the IR LED is switched on and off at a
rate of 38 kHz in order to send the needed data. The digital data being sent
(ones and zeros) is composed of a certain duration pulse for a one and a dif­ferent duration pulse for a zero. There are pauses with no carrier in-between
each one and zero data bit being sent for easy determination of the bit
boundaries. A common format for this type of data transmission is called
60/30 PWM. While this may sound complex, it really is not. Let’s take a closer
look.

PWM stands for Pulse­Width-Modulation (not
Pretty-Wild-Muscles). In
our case this means that
we change the amount of
time the IR LED is turned
on versus off in accor­dance with the data we
want to send. For exam­ple, let’s say we’re send­ing data at a rate of 1 bit
per second (bps). Each bit would take one second to send. To represent a
logical one, the LED must be switched on and off at a rate of 38 kHz for 60%

0Sec 1Sec

IR Remote
Output

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0

1

0Sec 1Sec

IR Detector
Output

0

1

of the one second time frame (0.60 seconds total of the entire second). For a
logical zero, the LED will still be switched on and off at a rate of 38 kHz, but
this time only for 30% of the total time (0.30 seconds total of the entire sec­ond).

When the IR detector “sees” a 38 kHz IR signal, the output of the detector
goes low (it is inverted). Conversely when there is no 38 kHz carrier signal
present, the output idles high. If you were to look at the output of the IR detec­tor you wouldn’t see the original 38 kHz carrier present, just the logical data
that the PWM 38 kHz represents from your IR remote control. If we want to re­send this data, we have to modulate a 38 kHz carrier again in accordance with
the data the IR detector puts out. There are a number of different ways we
could do this. One possibility is to turn a 38 kHz oscillator on and off using the
IR detector output as the switch, this lends itself to the problem of how fast our
oscillator can start up and settle however. A better idea is to go one step fur­ther and use a micro-controller to generate the 38 kHz carrier. The data output
from the IR detector can be sampled by the micro-controller which in-turn gen­erates a 38 kHz carrier signal that is Pulse Width Modulated (PWM) according
to the detected data.

By using this method with a micro-controller, we can add some intelligence
to the regenerated signal as well. The sample IR remotes we have looked at
send their data at a rate of around 2400 bits per second. This means that our
minimum pulse length for a zero should be 1/2400 x 0.30 seconds long (125
uS). Consider this example, let’s say that the signal from the IR remote is
weak and it fades out due to interference from some other IR source before
the data pulse is finished (i.e. 80 uS instead of 125 uS). The micro-controller
will continue to send the 38 kHz until 125 uS is up, not allowing the re­transmitted signal to drop out the way the original source did. This error cor­rection feature can be disabled in case you have a strange remote that is not
compatible (to this point we have yet to run across one that doesn’t work). Re­move the jumper from J2 to disable this feature and have U1 blindly re-create
the data it sees.

Once the micro-controller has re-generated your 38 kHz carrier (modulated
by the data), we buffer its output with transistor Q1 to drive the IR LED. The
current through the IR LED is limited by R1 and is typically around 50 mA.
This is pretty hard for an LED but don’t worry. Even though the steady ‘on’
state of a typical IR LED can only handle about 20 mA, we are switching the
LED on and off at 38 kHz during the entire send sequence. The LED may be
on only about 50% of the total time to send the data. To achieve the maximum
transmission range and peak performance from the system, we’ve cranked up
the current a bit to get More Power!!!!

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