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DiscoverCircuits.com -- Hobby Corner
Last Updated on:
Wednesday, June 02, 2021 03:50 AM
Hobby Circuits List
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More:
Switch Circuits
Light Dependent Circuits |
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24vac Powered
Day/Night Switch (Dec 26, 2010) |
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low voltage outdoor lighting systems use 24vac to power the devices. The low
voltage is much safer to use outside than standard 120vac or 240vac power systems.
This hobby circuit below is designed
to turn off power to outdoor lights during
daylight and turn them back on at night. This hobby circuit uses a
phototransistor to detect daylight. I would suggest you use a phototransistor
which has a built in daylight filter. These are colored a deep purple. The filter
helps insure the circuit reacts only to sunlight. |
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This hobby circuit uses a unique bidirectional switch network
made from two n-channel MOSFETs, wired in opposite directions. The DC
control voltage needed to turn on the two FETs is developed by tapping into
some power from the 24vac source through two capacitors. A small Schmitt
trigger inverter provides some hysteresis, so once the lights turn on, the
extra illumination does not turn the switch back off. With the
components shown, the circuit can easily handle 10 Amps of current. |
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Click on Circuit Below to view PDF of Schematic |
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Circuits Light Dependent Circuits
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eMail David A.
Johnson, P.E. about this circuit |
