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Wednesday, June 02, 2021 03:48 AM
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Remote Control;
Television Circuits VCR TV Remote Range Extender
Circuit
I often get frustrated by how poor some
infrared remotes in many new electronic devices operate. I used to be able to
turn on the TV from 30 feet away. Now, it seems that I have to get within 15
feet. To address this issue, I designed
the circuit shown below. The
circuit taps into the TV remote’s existing infrared LED and drives 8 more efficient
devices. The result is a communications range some 4 to 5 times longer.
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The circuit is housed in a low profile
plastic box. A Serpac H-65AA (Digikey part number SRH65-11B) has a nice
battery compartment for two AA cells. The circuit is powered by two standard
AA cells. I suggest including a 1.5 farad supercapacitor in parallel with the
battery to help supply the peak current needed by the 8 LEDs. A Nesscap
EMHSR-0001C5-005R4 has a very low internal resistance and a higher 5.4v voltage
rating.
Other supercapacitors might also work. Just
make sure they have a voltage rating higher than 3v. The recommended infrared LEDs
are made by Vishay, their part number TSAL6100. These are available from
Mouser, Mouser part number 782-TSAL6100. These devices emit infrared light in
the longer 950nm wavelength, which most infrared remote receivers expect.
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| When the VCR
remote’s LED turns on, there is a voltage drop of about 1.5v. This voltage is
sufficient to turn on the PNP transistor Q1. When Q1 is switched on, 3v is routed
to the gate of Q2, which switches it on hard. It routes current to all 8 of the
Vishay LEDS. With a 22 ohm resistor wired in series with each LED, the peak
current is set at about 60ma. This is about 4 times higher than most LEDs are
driven in a typical remote. By wiring 8 more LEDs to form a cluster, the range of
the remote should increase by a factor of least 5. So, instead of 15 feet, with
the added light, the distance should be closer to 75 feet. |
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Click on Circuit Below to view PDF of Schematic |
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Remote Control; Television Circuits
Hobby Circuits List
eMail David A.
Johnson, P.E. about this circuit |
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