This should be simple but I'm stumped because the load varies somewhat.
I have a lighthouse at the entrance to my harbor and the flasher circuit wants 6V DC in. For years I've been running it off a wall wart that powers up when the layout power is on. Lately I have been "streamlining" a bunch of my under-layout wiring and trying to eliminate the dozens of various power supplies I have for signals, Tortoises, draw bridges and lighting effects.
So, this light flasher that represents the West Quoddy Light runs on 6 volts and I'd like to wire it into the 12 volt regulated DC buss that I have running around the layout.
The thing is, the flasher draws 72mA and then spikes to 185 mA when the light brightens, then returns to 72mA for about 20 seconds when the light is dim.
I found this DC voltage regulator at All Electronics and wouldn't 'ya know, I just sent in a big order and didn't get one SO if I just order this one it will run somewhere over $20 with shipping.
http://www.allelectronics.com/make-a-store/item/dcc-3/step-down-dc-regulator/1.html
Can anyone point me to a circuit I could make that will supply 6 VDC off of 12 VDC? I'm afraid just resistors alone will not respond to the varying load and I'd hate to toast the flasher which was $25 back in 1990!
oo[edit]oo\ After doing a little digging, I found this kit that is for an LED lighthouse simulator and I kind of like it better! Rather than try to regulate the 12V I could just get this.
http://www.bakatronics.com/shop/item.aspx?itemid=575
Has anyone dealt with this business before?
Thanks, Ed
Yes. Get a LM317 voltage regulator. Couple caps and couple resistors. I have done that a lot for various voltages from a 12 volt power supply. I have done 1.5 volts, 5 volts, 9 volts.
Google lm317 regulator. There is a low current version also. 200 ma I think.
You will have plenty of links to keep.
Rich
If you ever fall over in public, pick yourself up and say “sorry it’s been a while since I inhabited a body.” And just walk away.
A LM7806 is a 6 volt 1 amp voltage regulator. With your requirements it will probably be OK without a heat sink. Or you can use a LM317 but it will need more components because the 317 is a variable voltage regulator.
http://www.digikey.com/product-detail/en/LM7806CT/LM7806CT-ND/1954727
Martin Myers
I've bought a few things from Bakatronics. The kits work as advertised. I don't have the kit you're looking at, though.
Because of the pulsed nature of the lighthouse, you might be better off just leaving it on the wall-wart, though.
It takes an iron man to play with a toy iron horse.
I've seen various DC-DC converters on eBay, same sort of Chinese sources as the cheap LEDs. A simple regulator will work as well, be sure to include the small .1 or .01mfd caps as shown on the data sheet, but since you already have DC in, that should be all you need. I think even with the 7806 you will need a heat sink because of the 50% voltage drop - in a linear regulator it all comes off as heat. I would put a few 1N4001 type diodes in series before the regulator to get the 12v down to 8 or 9 V before feeding the regulator, then it doesn't have so much voltage to drop and won't get as hot.
DC-DC converters are more efficient though.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
Thanks for the great solutions everybody!
Rich, Martin and Randy: I'm going to build the regulator with the suggestions you mentioned. I have a Walthers jack knife bridge that wants the lower voltage, too. It runs too fast at 12 volts. I had it running off a 6v lantern battery for a while! Actually, that battery lasted about four years... I didn't raise the bridge too often but visitors enjoyed seeing it move.
Mr. Beasley: I will order the LED flasher from Bakatronics as I like the pattern better but I'll probably still use the old flasher for some warning beacons on smoke stacks or radio towers...
Thanks again, Fella's
Ed