HELP: Looking for 24hr clock timer switch - 12 VDC

[McGizmo]

Hi Gang,

I have done quite a few low voltage LED light system installations and have assisted in many more. Typically these have been powered by wall warts and Malibu type timer/ transformers. I have done a couple that were powered by 12V gel batteries. I think there is a real advantage with having a battery in the circuit as this allows for the system to work even if the grid is down.

The Problem: These systems have all been set for either dusk to dawn operation (photo cell switch) or auto timed on/off cycles. To provide for auto switching on 12 volts, I have been limited to the use of photo cell switches as I have not been able to find a simple clock timer switch that runs on 12 VDC. Internet searches have yielded exotic timers for industrial applications but no simple 12V in 12V out with a clock to allow for setting on/off cycles.

Have any of you folks run across such a device? I would assume that the boating and R/V industry as well as those with off grid systems would have use for such a simple device and yet there seems to be a lack of availability.

In case I haven't been clear about what I am looking for, I am referring to something in similar function to the devices you can get at any hardware store that plug into the wall and you plug your device (lamp typically) into them. Either digitally or mechanically, you set the current time and then set an on and off time. I am looking for the same thing that works in a 12 VDC environment. Am I blind of off the wall in such a requirement? If the clock switch is limited in current capacity, I can always couple it with a 12V relay.

/ubbthreads/images/graemlins/help.gif

- Don

 

[Brock]

Dang, I had the whole thing typed and closed the window; I hate that when I do that.

Starting over, I have an intermatic timer that fits in the same place as single wall switch. It runs on a single AA battery and has all kinds of fun settings. I use them for 12v LED lighting and 12v CF lighting. They have a 7 day timer with I think 14 settings, momentary on / off and override. Pretty slick. I got mine a Home Depot, but I have seen them at a couple of other home improvement type stores. The catch is they cost about $25-$30. I looked around to see if I can find it online, I know I have seen it, but can’t find it again.

 

[McGizmo]

Thanks for the lead Brock. I guess I could get a buck circuit to take the 12VDC and step down to the 1.5 VDC to power the timer. Do you recall the current capacity of the timer?

 

[Brock]

Ah Ha, I found it

http://www.intermatic.com/consumer/ss7c.htm

all the spec's are there

you could run it of some sort of step down, but they run about 2 years on a standard alkaline, probably a lot longer on a lithium AA cell.

 

[McGizmo]

Thanks Brock!
I have seen those but with the "battery back up" statement, I thought they used 110AC as input and didn't realize I could through put 12 VDC. Cool! Thanks again!

- Don

 

[Floating Spots]

Re: HELP: Looking for 24hr clock timer switch - 12

It does look very interesting.
the spec sheet lists AC and DC loads and uses "hard contacts" (AKA. a real relay).

The spec/installation sheet is at
http://www.intermatic.com/techsup/ss7c.pdf
for those of you just tuning in.

 

[Brock]

Re: HELP: Looking for 24hr clock timer switch - 12

Yup, I think it is a latching relay, you can hear it "snap" on and off. Purely a switch from the contacts point, no power needed. I just wish it wasn't so much $ or I would have lots more of them. They are a great replacement for standard mechanical clock timers. I used to use mechanical timers on my LED nightlights, but when I metered a timer it was pulling about 50mA at 120v (6 watts), the LED only took 20mA (2.5 watts), so I was using more power to turn the light off then to let the nightlight run 24/7. Talk about a phantom load!

 

[StevieRay]

Re: HELP: Looking for 24hr clock timer switch - 12

McGizmo,

I have used these before. They work quite well.

http://altronix.com/p_html/PT724A.htm

 

[McGizmo]

Re: HELP: Looking for 24hr clock timer switch - 12

Thanks everybody!

It's funny, I have passed the Intermatic switch by many times thinking to myself, "if it only worked on 12 V" Duh! I guess I should have read the fine print? /ubbthreads/images/graemlins/grin.gif

- Don

 

[carbonsparky]

Re: HELP: Looking for 24hr clock timer switch - 12

Great item, I need one. Yes, 25 - 30 bucks means I will not get more than one but with the functions it is worth the price. I would not expect them to give them away.
Something I have contemplated using for lower voltage timers are sprinkler timers. They allow for multiple outputs at different times. I have never actually tried or researched this idea so how will this would work can not be answered by me.

 

[JSWrightOC]

Re: HELP: Looking for 24hr clock timer switch - 12

The sprinkler timers I have seen require a 24VAC input and use TO-92 cased TRIACs to swith the loads. Perfect for operating solenoid valves, but not for switching DC...you might be able to hack one, though. Make some measurements, but the 9V battery backup is probably not a critical voltage, so you might be able to feed it 12VDC. Some, however, may use the AC line for a timing reference, and refuse to operate normally without it (using it as a simple means of determining if input power is present or not). I like the Intermatic switch idea!