• If you have bought, sold or gained information from our Classifieds, please donate to SlipperTalk Forum and give back.

    You can become a Supporting Member or just click here to donate.

Light problem HELP ME !!

Slippertalk Orchid Forum

Help Support Slippertalk Orchid Forum:



Hi everybody

Ok this is the setup
Under the bench in my greenhouse

A 220V 400W MH - on a lightrail for my seedlings 10 hrs per day, is turned on and off by a timer.

What I want is :

The lamp goes on or off when the sunlight hits a certain level

Can this be done ?

Have not been able to find any photo cell so far

Any help will be much appreciated



I haven't seen a photocell version, but I just ordered some Smarthome products after Heather told me about her setup.

I ordered the Smartlinc V2 control module which plugs into the wall, and then into the computer with a USB port. There is a computer program that allows you to set all sorts of timer settings, including a sunrise/sunset setting, but it is calculated and not based on actual light.

You would also need an outlet adapter to plug into the wall for the light to run to. The control module has built in memory for storing the different timer settings you want, and sends those commands to the adapters.

This isn't exactly what you said you were looking for, but I thought you might want to see it. Check out their website at www.smarthome.com You might be able to find something that would better fit your need.


I googled "light sensitive switch" and found a few things that might work for you.


Jun 9, 2006
Reaction score
Mid Michigan
Whatever you do, build in a delay of some sort. You don't want your lights flicking on every time a cloud passes by. That will burn up your ballast and bulbs faster than you want to contemplate.

I thought about doing something like this, but it is the 'cloud problem' that keeps me from doing it. Haven't figured that out yet.

Jon in SW Ohio

Reefer, the legal kind
Jun 9, 2006
Reaction score
Springboro, Ohio
I'm pretty lazy and have yet to integrate the computer and my lighting, so here's my simple suggestion:

Buy a good timer that has 15 minute increments. Check the greenhouse at different hours and determine roughly when the sun is hitting the area when you don't want artificial lighting and set the timer off at those times.

Obviously this won't be as accurate as a light meter triggering device, but since you're using a MH you probably don't want it turning on and off a bunch of times each day since that can greatly shorten the life span of the light. Changing seasons may make the hours different every couple months, but most of these timers just use little pegs you push in or out to change the times so it shouldn't be too tedious to adjust one or two every couple months.

Last edited:


Well-Known Member
Jun 9, 2006
Reaction score
Leiper's Fork, TN
Radio Shack had some very unsophisticated photo switches in their alarm and security section. These were designed to turn household lighting on at night in the absence of the homeowner. These should also be the same switches used in street lamps. I'm not sure if any of these have means of changing sensitivity to lighter situations during the day.

Uri, you may also have to go through a contactor since the voltage requirements of your lighting sytem may exceed the capacity of the switch.

Latest posts