Timer Circuit for Structure Lights

[seaside]

This is an extension of the thread regarding LED structure lights posted several days ago.

I plan to use 555/556 timers to intermittently turn on/off selected structure lighting for a more realistic appearance over time for night time operations. I understand that these chips can sink/source up to 200 mA by themselves which may be enough for incandescent bulbs but I plan to use LEDs.

My general thoughts are that the circuit would be installed in the building with only the + 9 volt dc power leads extending though the benchwork to my lighting bus. The timing would be to turn on/off lights over a period of minutes and the duty cycle would vary in each building so they don't blink like Xmas lights. Some building will have lights always on so I plan to only have circuits in maybe 20% of the structures.

Does anyone have a design for such a circuit or any thoughts on parameters that should be included in my design?

John

[jalajoie]

I don't want to hijack the thread, but I am also looking for a similar circuit that will randomly power on and off, a Circuitron Arc Welder Circuits. This combine to the random flickering built in in the Circuitron should provide a very realistic effect. 

[richg1998]

Store the link in Favorites.

http://home.cogeco.ca/~rpaisley4/CircuitIndex.html

Rich

[Alantrains]

Hi John,

there are plenty of 555 projects around that will do what you want, but each one will only have one timed interval.

A Microcontroller or in  my case a PICAXE is an easily programable I/C that can have from 5 to 15 outputs. I plan on using a small 8 pin PICAXE 08 to switch my structure lights on and off. You can set the time or let the program randomly select the time for each individual output pin. Each output can drive 20ma enough for a LED or two in series. Not as good as the 200ma a 555 can source, I must admit.

If you know some old BASIC then programming a PICAXE is easy and they are pretty cheap. The software for them is also free. Just google PICAXE.

If your more familiar with 555s then use them, but the PICAXE will give you more flexibility.

cheers

[ccg]

Hi john

I have been in model railroading only since last march, but I have been in industrial controls for 46 years. When I started building my layout, as you do,  I also wanted all of my residental structures to have both floors separated and divided in half, giving me four lights in each 2 story structure. each light was to cycle at a different time interval. I also wanted my traffic lights to function as real traffic lights do. After looking at the cost of all of these control systems, I decided to use a programmable logic controller (PLC) for all of my lighting and controls on the layout. I am also inputting all of the train detector circuits into the PLC, allowing me to control train signals and crossing gates. My layout has no electronics out on the layout, all of my controls are done thru a laptop computer talking to the PLC. The PLC system allows me the flexibility to keep the interior lighting at 8 volts and the exterior lighting at 12 volts for more realistic incadesent interior lighting. Using a PLC control system, there is no limit to the control of your layout. Used PLC equipment can be purchased on line at a reasonable cost. I am using an Allen Bradly PLC 5-30 ($75.00 used), a 16 slot chasis ($100.00 used), and various input and output cards at about $20.00 each used). This type of system may not be for everybody, but it has eliminated the cost of 95% of the electronic control systems on my layout. The welding that was mentioned, I did with a simple light in my round house that is fired randomly by the PLC.

just my thoughts  

CORBYN CITY GEORGE

[gandydancer19]

I had an old washing machine timer that had a lot of electrical contacts on it.  It ran on 115VAC for the motor only.  This would seem random in some situations.  I don't know if today's timers are mechanical or not, but it might be something to consider if you have access to a junk pile.

Just another idea.