convert landscape 12 volt lighting mechanical timer to "dusk to dawn"

readingalot

I know I can buy a dusk to dawn time and plug my failed mechanical Intermatic Malibu landscape timer into it but I would like to know if there is a fairly simple electronic circuit than can be built into the timer because I have several of them.

These Intermatic timers are known for a stripped plastic gear that cannot be replaced.  The timer runs of 110V and has a transformer that supplies 12 volts to the lights.  The output for most of my timers are around 800 watts.   Can I run a circuit off the 12volts that will switch the line on and off through use of the dusk to dawn sensor.   I have seen some of the circuits on this site that switch one or more LED's but none that will work for 800 watts off the 12 volt circuit. 

Some of the newer circuits have such a circuit and include a feature to shut off the lights after a preset time but I don't want to get that complicated.

Thanks

readingalot

I did misstate the output as 800 watts but is it a little over 80 watts, probably 88.  It controls about 12 lights that use 5 watt bulbs.  Slowly converting to LED's but not there yet.  It should also have been noted that the output is 12 volts ac, so there is no dc voltage present.