Ramsey Electronics manual Output, RR1 Theory of Operation

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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 cir- cuit, 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 in- terference 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 dif- ferent 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 Pulse-

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

0

 

 

 

 

0

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Width-Modulation (not

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Pretty-Wild-Muscles). In

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

our case this means that

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

we change the amount of

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

1

 

 

 

 

1

time the IR LED is turned

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

on versus off in accor-

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

dance with the data we

0Sec IR Remote

 

1Sec 0Sec

IR Detector1Sec

want to send. For exam-

 

ple, let’s say we’re send-

 

Output

 

 

 

 

 

 

 

Output

ing 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%

RR1 • 5

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Contents Ramsey Electronics Model No. RR1 Ramsey Transmitter Kits RR1 Remote Repeater KIT RR1 Introduction RR1 Theory of Operation OutputRR1 Kit building tips Ramsey LEARN-AS-YOU-BUILD Assembly StrategyRR1 Capacitors Parts Supplied with Your RR1 KITRR1 Remote Repeater KIT Assembly RR1 RR1 Testing the RR1 Using the RR1 Troubleshooting Guide RR1 RR1 Parts Placement Diagram RR1 Specifications Ramsey Kit Warranty RR1 Remote Repeater KIT Total Solder Points Estimated Assembly TimeRequired Tools Additional Suggested Items
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