Wiring for lights

[Camarokid65]

If this is the wrong place for this question, my apologies. I am using some 6.5v 68ma grain of wheat bulbs on my layout, powered by a 18v model rectifier dc train power pak i had with no other use. I tried these bulbs at first on the power packs accessory terminal first and it was apparently too much and blew the bulb. ok then. So i then put a few on the dc power terminal. Initially they work fine with me using the speed controll of the power pack as a dimmer, thereby i figured using less power and i had no issues until once i added the 6th bulb, it didnt want to power any of the bulbs. If i take that 6th bulb off, the other 5 are fine. Im no electric goo roo and Im learning. So, what kimd of power supply do i need for these bulbs so that I can use several without having to use so many power supplies? Obviously being a 18v power supply if i didnt "dim" the others Id blow them out. I know this isnt the right way to do this hence why Im asking. 

Thanks

Del

[RR_Mel]

Depending on how many bulbs you will end up using you could get a 5 or 6volt wall wart.  If you bought a sack full of the bulbs like I do buy a 5 volt power switching supply off eBay.  The bulbs will be slightly dimmer but will last for ever running on reduced voltage.

 

1 amp = 1000ma, multiply the 68ma by the number of bulbs to size the power supply.

 

 

 

Mel

 

 

 

My Model Railroad   

http://melvineperry.blogspot.com/

 

Bakersfield, California

 

I'm beginning to realize that aging is not for wimps.

 

[rrinker]

 If you are using these in buildings, less than full power should be good. So try this. Hook 4 of the bulbs in series. That's

----O--------O--------O------O------

hook the free ends to the 18V terminals. The should light, but not insanely bright.

Now if you need more than 4, hook another 4 up just like the first 4, and hook the free ends of those to the power pack terminals, combined with the wires from the first 4 lights. This puts each group of 4 in parallel with the other group of 4.

 Depending on the capacity of your power pack, you should be able to run at LEAST 5 strings like this, 20 bulbs in total, and probably closer to 10 strings, 40 bulbs.

 If they are too dim, try strings of 3 bulbs each, that's a lot closer to the 18V rating of the power pack and may be too bright though - that "18V" output may well be a couple of volts higher with a light load. So try strings of 4 bulbs first. 

                               --Randy