Using a standard PC-sound card and straightforward circuit, you can implement low-cost on/off control of home appliances via the Internet. The system (Fig. 1) consists of a local computer (located where you are) and a remote computer connected to a simple and inexpensive interface circuit with relay output. The local computer needs a browser and an application which offers access to the remote computer over the web, as if you were sitting right in front of it...
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