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| Infra-Red
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Single Channel Switch : Transmitter |
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The component values must be chosen to give a frequency of
oscillation to suit the receiver module to be used. In
most cases this will be 40kHz but you should verify
this before starting construction. The resistance in
series with the diodes should be about 22W
(its value is not critical). To
calculate the frequency of oscillation of a 555
oscillator, use the following formula: |
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| For example,
if we choose C = 1·5nF and R2 = 10k this gives
R1 = (about) 5k for a frequency of 40kHz. We
should therefore use a 10k variable resistor for R1.
This will allow us to set the frequency to exactly 40kHz.
For stability of frequency, a voltage regulator is
recommended (the vero diagram includes a regulator). |
| Vero diagram |
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Single Channel Switch
Two
Channel Switch
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© David Hoult 2009
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