Good Evening All.
I need to build a circuit that will activate a solonoid (on a water valve to water the plants while I'm on holiday!) at dusk, and remain on for a adjustable pre-set time.
I've come up with the attached design - LDR and comparator trip a 555 flip flop (when it gets dark) to turn on the output transistor and a 555 timer. The timer pulses every 30 seconds to a 4017 which drives an LED indication of time elapsed.
The 4017 outputs also feed via selector switch a transistor which will reset the flip flop and turn off the water. This theory seems sound to me, but before I expend the effort of building it, I'd appreciate any suggestions from the forum to improve it, or if you can see some obvious mistake I've made!
Thanks and Best Regards,
Ian.
I need to build a circuit that will activate a solonoid (on a water valve to water the plants while I'm on holiday!) at dusk, and remain on for a adjustable pre-set time.
I've come up with the attached design - LDR and comparator trip a 555 flip flop (when it gets dark) to turn on the output transistor and a 555 timer. The timer pulses every 30 seconds to a 4017 which drives an LED indication of time elapsed.
The 4017 outputs also feed via selector switch a transistor which will reset the flip flop and turn off the water. This theory seems sound to me, but before I expend the effort of building it, I'd appreciate any suggestions from the forum to improve it, or if you can see some obvious mistake I've made!
Thanks and Best Regards,
Ian.
Attachments
-
17 KB Views: 49