Miniature Real-time Controller

Posted on Sep 28, 2012

This is my long history the device that controls my home`s night light, air-conditioner,etc. The device is a Miniature Real-time Controller. The circuit uses only three chips, a 89C2051, DS275(or MAX232), and 74LS07 open collector driver. The scheduler for time on/off of 6-channel output can be made by downloading from PC and saved into onchip RAM. Each output provides a 20mA sinking suitable for driving a homemade opto-triac or big solid-state relay for heavy load.

Miniature Real-time Controller
Click here to download the full size of the above Circuit.

A circuit diagram of the Miniature Real-time Controller is shown in Figure 1. A 89C2051 with a low-cost X-tal 3.579MHz runs timer6.hex. The 6-channel output is P1.2 to P1.7 driving with sink current. A 74LS07 open collector provides approx. max 20mA @12V

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