ODWS icon The Open Door Web Site
Site Map
> Electronics
History of Science and Technology
Math Studies
Learning French
Study Guide

Infra-Red Switch


Single Channel Switch : Transmitter


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:



For example, if we choose C = 15nF 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

Single Channel Switch

Two Channel Switch

Top of the Page

Privacy Policy

Sponsored Links

Sponsored Pages

Donating to the ODWS

Advertising on the ODWS


Electronics Homepage

The Open Door Team
Any questions or problems regarding this site should be addressed to the webmaster

David Hoult 2017