Light Sensing Switch

[Irmamusic]

Apologies if this is inappropriate use of the forum, but having searched the internet for over a year without success I am wondering how feasible it would be to produce a light sensing switch, which would allow mains power to be supplied when the light intensity is above a certain number of lumens i.e when the sun is shining brightly. I (and thousands of others) have solar panels which generate considerable excess energy, so a method of switching on a fan, slow cooker based on light intensity would be invaluable.

I can find plenty of dusk to dawn switches - the opposite to what I need. I have looked at thermostatically controlled plugs but they switch off when the temperature is high, rather than coming on when the temperature is high.

If anyone knows of anything that would solve my problem or can let me know if it feasible to build something like this (as I know very little about electronics) I would really appreciate it

[David]

I'm rather surprised that you can't find a suitable switch on the net. However, as you need to get an inversion of the switching function why not feed the output of the dusk - dawn switch to another relay with a set of changeover contacts (careful with output voltages from the D - D switch and the new relay coil), and wire the contacts of the added relay to give you whatever switching function you require.

Hope this helps

[Irmamusic]

Many thanks David - I really appreciate your response.

I must admit I had been looking online for a custom built solution, but I have now begun to look at electronics kit solutions and see that Quasar seem to do a 1004KT light relay switch kit which looks as if it could do the job. As I said I have no real knowledge of electronics but this might be a solution.

Thanks for confirming the feasibility of such a device and for opening my eyes to a new direction:D

[David]

Thank you for your comments. I have looked at the 1004KT kit, and it seems to have the right type of output you need - i.e. mains switched via normally closed or normally open contacts. This means that you can choose whichever function you want. The only restriction is that the on-board relay has a current rating of 1 amp, and if (as I expect) your fan/slow cooker etc. has a current drain of more than this, you will need to use another relay which can handle the higher current switched by the on-board one. Check the wattage rating of the devices you want to use, and reckon that roughly 250 watts = 1 amp drawn.

[Irmamusic]

Thanks again David. I am indebted to you.

My fan is rated at 60w and my Slow Cooker is rated at 130-163w so with a bit of luck the current relay may do the work. The challenge now will be attempting to put the kit together!!

Thanks again for your help