Lighting help

fiveoffive · Post by **fiveoffive** » Tue Mar 24, 2009 9:15 pm

Greetings. This is my first post here. I haven't had a chance to look through the posts, but from what I've seen, I'm gonna like it. I am building my first diorama. I am using standard off-the-shelf 12V dollhouse lighting (incandescent) and a 12V transformer (AC). I am trying to figure out a way to get the lights to alternate between being on and off for two seconds each. On for two seconds, then off for two seconds, then on for two seconds...continuously. How can I do it? Any help would be greatly appreicated.

jwrjr · Post by **jwrjr** » Tue Mar 24, 2009 10:43 pm

Powering the lights from 12 volts AC complicates things, but it can be coped with. The simplest solution involves a CMOS 555-type timer (a 7555 or an equivalent) and a solid-state-relay. The regular 555 will not cope well with the long timing period. A regular relay can do the job, but, being mechanical, it will wear out. It would be simpler if you were using a 12 volt DC power supply. Then, a transistor (I prefer MOSFETs) could be used.

fiveoffive · Post by **fiveoffive** » Wed Mar 25, 2009 4:23 pm

Thanks for the reply. Here's another bigger problem I have, I know NOTHING about electrical circuits or dioramas or model building. I need to find something ready made that I can just plug into the equation and it will work. I appreciate your help with the circuit. I looked it up online and it looks like something that would have to built into something else to make this work. Maybe I'm just wasting my time, but I know that somewhere out there this has to have an answer. Afterall, neon signs have been blinking this way since the beginning of time. I know it's out there.

Kylwell · Post by **Kylwell** » Wed Mar 25, 2009 4:27 pm

Try your local model train supply store. They've got all sorts of flashers & what-not.

Or, try to find an LED battery Christmas light set. I've got a set that does 10 lights alternating 5 to a side.

fiveoffive · Post by **fiveoffive** » Wed Mar 25, 2009 4:30 pm

I already tried the train places in my area and I can't go with battery. The dorama is already built and the lights are installed. That's how confident I am that I will get this solved.

Sparky · Post by **Sparky** » Wed Mar 25, 2009 6:32 pm

http://www.electronickits.com/kit/compl ... nck002.htm

You will have to figure out how much current the lights are using, this think is limited to 50 mA.

If you need more and still need the drop in ready, you'll need to hunt some more. Also this circuit is not good fro the durations that they list (555 timers are not good for pulses >60 seconds or so).

Also I'm guessing that while you have an ac 12 volt transformer the output is 12 volts DC. I don't think there are many grain of wheat bulbs that are AC.

fiveoffive · Post by **fiveoffive** » Wed Mar 25, 2009 6:49 pm

Adapter says: AC ADAPTER MODEL MH 40120 Class 2 plug in Transformer with lead in wire. Circuit Breaker Protected. INPUT: 120VAC 60 Hz 250 Ma OUTPUT: 12VAC 20.4 Watts Indoor Use Only.

Lights just say 12V bulb.

I am using 7 seven bulbs total, all connected in series.

jwrjr · Post by **jwrjr** » Wed Mar 25, 2009 11:15 pm

Incandescent bulbs don't care whether you are using AC or DC. It is an issue for leds, though (obviously).

Sparky · Post by **Sparky** » Thu Mar 26, 2009 1:07 pm

Something like this:
http://www.electronickits.com/kit/compl ... EK2599.htm

But you will need a separate power supply for this unit, 12 volts dc. Most drop in replacements will need a Dc power supply, unless they have the power supply built into them.

Search for electronic kits, there are other supplier's out there, got a Fry's nearby? they have kits like these.

fiveoffive · Post by **fiveoffive** » Thu Mar 26, 2009 2:51 pm

I'll look into it. Thanks

fiveoffive · Post by **fiveoffive** » Thu Mar 26, 2009 6:02 pm

That type of device can be programed to make the intervals between wipes start at different times, but the wipe itself is a 'flash' not a steady on. I need steady on for two seconds then steady off for two seconds. By the way, where on this site can I find photos of the work people upload? I didn't want to start a thread to ask that.

Sparky · Post by **Sparky** » Fri Mar 27, 2009 1:00 am

Ah its a bit tricky now, the main site is .com, while the forums are .net

http://www.starshipmodeler.com/gallery/gallery.cfm

You can search the gallery now for work submissions as well as for hobby shows that were reviewed. Its all under the general topic of galleries now. If you are looking for 'how to' articles though its somewhere else on the main site.