I am looking for a DC power souce to power my 12 Volt lighting and my tortorise switch machines.
I am looking at three power supplies that put out 12 Volts DC. One is 34 amps, one is 20 amps and the last is 19 amps. The difference in price from the 34 amp to the 19 amp is $35.
I believe the 19 amp model is converted from a computer power supply where the other two are normally used to power raido control battery chargers.
Can these be used to do the job? And are these powerful enough to power tortorise switch machines & lighting on an entire 15x20 home layout?
Are you sure you are talking AMPS? A 19 amp power supply would power the most powerful railroad I can think of. If they are switching type supplies the weight would not be too great. A 19 amp analog supply would weigh in at about 30 pounds. We also need to consider the filtering and regulation. Some so called 12 volt supplies are actually much more than that until they are loaded near capacity.
Two of the three are regulated switching type power supplies.
I use to be into R/C car racing and had a power supply similar to these, it weighed around 25 lbs. Weight is not a factor since this is a permanent layout.
The one I sold was top of the line and put out 45amps that I used to power instruments that measured the power of the electric motors as well as being used as a power source for operating armature lathes and to use as a power supply for battery chargers. So yes I’m talking amps.
The more expensive supplies have adjustable voltage from 11V to 13.8 under full load. Is this going to be too much for my application?
We’re not dealing with silly tactical nukes here, are we? The real name of the game is global annihilation, isn’t it?[:D]
I assume you are planning to use nothing smaller than 4 gauge for your accessory wiring bus. And attach welding tips to your feeders. [:D]
Seriously, each Tortoise in the stall state draws about 20 ma. 12 volt grain of wheat/rice light bulbs used on layouts are typically around 50-150 ma. LEDs are back in the 20 ma range.
The 34 amp supply would be a fire hazard to use without special wiring and circuit protection. 12 gauge wire is rated for 20 amp circuits in household use. I would not want bigger than a 20 amp supply under any conditions, and my personal preference is to keep all my mr power supplies 5 amps or smaller. Even with the 20 amp supply, I highly recommend fusing/protecting circuits individually, or at least in groupings of less than 5 amps total. Model railroads are magnets for accidental short circuits, especially on and at the track. Allowing a 20 amp short circuit current for even a few milliseconds is hazardous to your models. Major wheel-to-track arcing and sparking will occ
I could offer a simpler soulution… Those inexpensive power packs from starter sets work good…By using the track circuit, your street lites can be brightened up gradually, like in the real world…same thing with accesories, they can look more realistic running ar a lower speed (voltage)…switch machines may last longer…
Sounds like a lot of overkill. A Tortoise only draws .018 amps at ‘stall’. I have an old ‘wall wart’ power supply that puts out 12 VAC with a capacity of .85 amps to power my Tortoise motors. That will power over 50 Tortoise motors!
I use cheap surplus ‘wall warts’ for lighting in structures. I picked for up free, a bunch of old Nokia cell phone ‘wall warts’ at the local Good Will(they wanted to get rid of them), but I had to take the cell phones as well(I had to dispose of the batteries). A week later the city had their ‘recycle’ event and I dropped of the phones with their batteries for free. I kept about 2 dozen of the 3.7 VDC/340 ma ‘wall warts’ for lighting my LED’s(much cooler that bulbs). I just needed dropping resistors for the LED’s. These units are small enough that I can plug 5-6 of them into a power strip…
If I understand them, power supplies do just that. They have a rating, and are meant to be operated safely at their max stated rating.
If you were to use the device you mention, and can keep the voltage down to the max intended for the various processes and devices you are going to power, then the huge amperage capacity of this device will not be used by a long shot, so yes, it is overkill. But, you can still use it…provided the voltage is carefully regulated, and that the device can be safely regulated. It will only provide the amperage required to do the highest level of work by any one device, or a series of them.
The cheapest 19amp unit is complete overkill but should work fine. No sence spending the extra $35 for the bigger one. The advantage of using an old computer power supply is it puts out 3.3v,5v. and 12v all at the same time. You don’t have to mess with resistors for your lights and LED’s when using the lower voltage lines.(for the most part)
At work I get a lot of used 12v wall wart power supplies back when the things they power die. I took two of them and wired them together to use a DPDT switches to power my Torti. 1amp max out of each of them and I can probably run a dozen Torti simultaneously off them.
Look around - what wall warts do you have sitting around from dead electrical components?
Tortoises draw about 15-20ma. That’s .015-.020 amps each. 100 Tortoises would draw between 1.5 and 2.0 amps. Do the math - even the 19 amp supply is probably overkill, even if you have a few hundred GOW and GOR bulbs to go with the Tortoises.
What you DO need if you use a power supply that large are several circuit breakers, a short at 12 volts and 19 amps is nearly 240 watts. Ever touch a 100 watt light bulb? Break out that 19 amps into a bunch of smaller circuits limited to 1 or 2 amps tops.
any of you boys just waitin’ for me to lay in on this one so you can beat me to death why don’t you run in and flush the toilet a couple of hundred times while you’re waitin’. I learned my lesson!!!
A ‘wall wart’ power supply is those little blocks you plug into a wall outlet, and have a wire several feet long coming out of them. They are used to charge rechargable batteries/etc…
I used to use a 25 Amp supply, but then a screwdriver fell across the track. It welded itself to the rails. Then the ties started smoking and the rails deformed. In the end, it pretty much destroyed an entire small layout. I’m not sure a 35 Amp supply would have done any worse, unless the whole thing caught fire…
I would definately put a fuse inline right at the power supply terminal. No more than five amps. If your load got up around four amps, you could use another five amp fuse, and start another circuit.