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Category: Hardware hacking
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I have been asked to deliver a low-voltage disconnect circuit for potential future production. It would drive a 15w load and protect a 12v sealed lead-acid (SLA) battery.

Features:

See http://hlt.media.mit.edu/?p=1695 for an awesome reference on using an Arduino UNO for the programmer, as well as the drivers for the ATtiny series. http://techhouse.brown.edu/~dmorris/projects/tutorials/transistor.switches.pdf is a great reference for transistors-as-switches.

The circuit is similar to that used in the LVD Project, with some minor variations for this application:

The sketch is included below (attached), as a single sketch requiring no external libraries. It runs in 2,134 bytes of FLASH (about half the capacity of the ATtiny45).

Parts

Note that all resistors can be 1/8w.

Contact me if you are interested in a custom application.