The Meter Clock

The clock is based on an Atmel AT89C2051 microcontroller.

It's actually a pretty simple circuit.

The software in the microcontroller handles the count for the time. It "talks" to a 4 channel Digital to Analog converter to derive the voltage to position the needles on the three meters.

The outputs of the D2A converters are buffered with a quad amp.
Otherwise the current draw of the 1ma meters would exceed the D2A converter.

A Dallas DS1307 generates an accurate 1hz timing signal and also backs up the time setting in the case of a power failure.

It's very cool to watch the seconds meter raise as a minute progresses and then falls again to zero.

The clock runs in a 24 hour mode.