Hi there
Hope this is the right forum to post in for this question.
I will be installing 13 Tortoise switch machines on my layout.
I have an old Marklin PSU that I intended to power the switch machines with.
There is an output terminal on the PSU that is rated 12vDC @ 2amp. Do you think this will be enough power for the 13 Tortoise machines ??
Many thanks in advance for your replies
bagman wrote: Hi thereHope this is the right forum to post in for this question.I will be installing 13 Tortoise switch machines on my layout.I have an old Marklin PSU that I intended to power the switch machines with. There is an output terminal on the PSU that is rated 12vDC @ 2amp. Do you think this will be enough power for the 13 Tortoise machines ?? Many thanks in advance for your replies
Enough to power 80 -100 of them. I generally allocate 20-25ma each for them and try not to exceed 75% of the power supply maximum current rating.
Engineer Jeff NS Nut Visit my layout at: http://www.thebinks.com/trains/
Hi guys
Thanks so much for replying.
You've got me worried now if I might be using too much power.
I noticed on the old Marklin transformer there is another output terminal rated 0-12vDC @1.5amp.
I'm wondering if this was to be used to actually control the trains on your layout.
Should I use that terminal instead of the 12vDC @2amp and set the control toggle at about half-way ??
Appreciate your replies
bagman wrote: Hi guysThanks so much for replying.You've got me worried now if I might be using too much power.I noticed on the old Marklin transformer there is another output terminal rated 0-12vDC @1.5amp.I'm wondering if this was to be used to actually control the trains on your layout. Should I use that terminal instead of the 12vDC @2amp and set the control toggle at about half-way ??Appreciate your replies
The only way you can use "too much power" is if the voltage output is a lot higher than 12VDC. The Tortoises will only draw as much current (amps) as they need. So you could have a 12V 5A supply (what I use) and 13 Tortoises may only draw .3A or less. The remaing 4.7A would just not be used. But if you plug the Tortoises into a 30VDC supply, they may burn up because they are rated for a lower voltage of 12-15VDC. The higher voltage would force them to draw more current and might burn up the coil inside. I've never tested one to maximum to see what voltage would cook one.
Tortoise motors draw extremely low amperage current while it does require 12 volts to operate properly,so setting your variable voltage (0-12v) control half way IS NOT a good idea as the reduced voltage will slow them down even more,that is if they would work at all.
However,the ONLY drawback to excess available power I can see is if a short circuit ever showed up.Should a Tortoise motor get shorted or a wiring problem develop,2A is more likely to melt the Tortoise much faster or worse smoke your wiring with the fire hazard that goes with it.For peace of mind,simply install a .5A fuse at the outlet of your power supply and the risk is taken care of.
Have you given any thoughts as to the future power needs of other accessories you well add later?
With a little work you can power a Small to Mid-Size layouts accessory needs (Lights, Tortoise Switch Machines, etc, etc) along with any number of things with just one computer power supply.
Cost to build test unit1 used PC power supply (I used an ATX unit)________$0.00 1 used 1157 automotive tail light bulb_______________$0.001 case mounted fuse holder_______________________$1.501 hour of my time_______________________________$0.00experience gained______________________________Priceless
johnnny.reb49a - Hobby Power Supply
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Jacktal wrote: Tortoise motors draw extremely low amperage current while it does require 12 volts to operate properly,so setting your variable voltage (0-12v) control half way IS NOT a good idea as the reduced voltage will slow them down even more,that is if they would work at all.However,the ONLY drawback to excess available power I can see is if a short circuit ever showed up.Should a Tortoise motor get shorted or a wiring problem develop,2A is more likely to melt the Tortoise much faster or worse smoke your wiring with the fire hazard that goes with it.For peace of mind,simply install a .5A fuse at the outlet of your power supply and the risk is taken care of.
Please excuse my ignorance, but when you say " install a .5A fuse at the outlet of the power supply", would that be to just one of the terminals ?
In other words, I have 2 terminal lugs for the 12vDC 2amp outlet. Would I connect the fuse between the wire running from one of the lugs to the switch machines and the wire running from the other lug, just connect to the switch machine as normal ?
Once again, appreciate your assistance
No! The fuse would be inline on one wire only. Preferably the red or positive wire.
wire fuse
+ ____________[=======]____________
wire no fuse
- __________________________________
Johnnny_reb wrote: No! The fuse would be inline on one wire only. Preferably the red or positive wire. wire fuse+ ____________[=======]____________ wire no fuse- __________________________________
That's what I was thinking should happen, but just needed confirmation.
Thank you for replying and confirming.
Appreciated
cheers
I have several control panels at various locations around my layout using miniature toggles to control the Tortises.The yard panels have 10-15 each,others only 2-5. I am using a regulated 12v 2a power supply. I would like to provide protection against shorts,as well as be able to identify which panel the short is originating at if one occurs. Would the 1157 taillight bulb satisfy my needs?...ie,would it keep a short from arcing and causing a fire hazard,and would it light enough for me to determind where the short was coming from?
Thanks Tom
tomwazy wrote: I have several control panels at various locations around my layout using miniature toggles to control the Tortises.The yard panels have 10-15 each,others only 2-5. I am using a regulated 12v 2a power supply. I would like to provide protection against shorts,as well as be able to identify which panel the short is originating at if one occurs. Would the 1157 taillight bulb satisfy my needs?...ie,would it keep a short from arcing and causing a fire hazard,and would it light enough for me to determind where the short was coming from? Thanks Tom
Tom, in my power supply test unit the 1157 bulb is acting as a load. Its fools the power supply into thinking it has some thing to do when it does not, so the power supply thinks it needs to put full voltage out to all leads.
Simply put 1 amp = 1000 ma
If you use a 1157 bulb inline in your power feeds and the amperage drew is high enough the current flowing throw the bulb will make it glow. As for short protection I would use inline fuses on the main power feed before it splits of to the control panels.
With that said, your power supply has a max raging of 2amps so I would start with a 1amp fast acting fuse.
On my power supply I started with a 1amp fast acting fuse. It popped as soon as I turned it on, then I tried a 1amp slow acting fuse. It also blow that one but not as fast. After checking my wiring I tried a 2amp slow acting fuse. That fuse is holding for now, but I only have a few test lights hooked up to it right now.
A fuse is simply your best short protection hands down!!!!!
A 1157 bulb is a practical item as it will indeed indicate the presence of excessive power draw and/or a solid short circuit,but this is only good if you're there to see it and investigate right away.A 1157 draws approximately 2 amps,meaning that it will glow proportionally to the current draw up to these 2 amps and I personally see two reasons why I don't favor this solution.
First is a safety reason.Let's say you leave the room for a while leaving the layout active without anybody present,and some component chooses that moment to act up and create an undued load (short circuit or overheating or else),the bulb will glow and in theory,take care of the short.True indeed in most cases and I agree.However,the 2 amp necessary to turn the bulb on is still present all around the loop the current travels from the power supply and back to it through what is commonly called the ground wire.Not a problem in theory but where I hesitate is in the fact that many layout devices are powered with such small wiring that many couldn't support a 2 amp load for a prolonged length of time.On the other hand,the fuse,considering it is the right grade,will react in popping off thus relieving the whole circuit of any load.As been said,the fuse is the best safety protection hands down.
The other drawback,although minor,is that the 1157 will glow proportionally to the current draw meaning that a small draw will not have it glowing enough to see it do so,but will have it start to create heat,thus wasting precious energy.I've read that some modelers use them to divide their layouts in zones and to avoid the command station shutting down in the advent of a short.It is a clever solution and no big deal with running a loco or two,but I question myself if it does affect the power level when running multiple engines.Probably not significantly,but still,I'd be curious to know.
Thanks Johnnny and Jackal. I was trying to kill two birds with one stone...protection from a short and making it visually obvious where it cam from. The fuse will work better for the protection,which is paramount,so I guess I'll go that route. Thanks again for your input.
Tom