Powering turnouts

[pathvet9]

I have been reading that it seems desirable to power all turnouts on separate power source from the DCC buss. I have a few old wall warts in a drawer, 2 of which run 12v @ 300ma & 500ma respectively.

I plan to run up to 10 MicroMark Switch Tenders on this circuit and wonder if that will be enough power? It is my understanding that these switches constantly use power to hold the points in place? Thus, does anyone have any idea how much amperage I will need for 10 of them. MicroMark as usual is no help.    

 

[Texas Zepher]

 Take one of the micromarks.  Hook it up.  Put the amp meter on it and give it the power.  It should record the max current draw when it stops moving (stall current).  Multiply that number by 10 and see if it is under your 300ma. or 500 ma. limitations.

[cacole]

 There's a discussion about the Switch Tender from Micro-Mark as compared to a Tortoise and Switch Master machines in the General Discussion forum.  According to Tony's Train Exchange testing, a Switch Tender draws 65mA at stall, so using more than two would put a lot of stress on the wall wart.

http://www.tonystrains.com/technews/mmark-switch-tender.htm 

[pathvet9]

Thanks for the tips. I do not have an amp meter, only a cheap multimeter so I can only guess.

Am I  correct in assuming that if I use these switches, there will always be a current draw on each as they hold the points in position. Thus, if the rating is 65mA, that is always being drawn as the switch is active? So, 65x10 is the minimum amperage that would work?    

[jrbernier]

Jake,

  Stall motor units always have the power applied.  Myself, I use Tortoise motors(they draw about 17-18 ma at stall).   I have an old 850 ma 'wall wart' that powers my Tortoise motors - It should be good for almost 50 Tortoises!  You can buy them at a 'street price' that is less that the price of the Micro-Mark 'Switch Tender' motor.  Search around on the Internet.

Jim Bernier

[pathvet9]

Thanks Jim - now I must try to get MicroMark to take back 9 units - or maybe try to sell them to someone else who is better equiped to use them than me? Unfortunately I bought them a year ago and then had to leave the country, just lately returning to my layout. Such is life!

[Seamonster]

I found by experimenting with the Switch Tenders that they will hold the points over with the power removed. I did my experimenting with Atlas N scale turnouts. Even when I tried to pull the points away from the stock rail, they pulled right back when I let go. So, I apply the power to my Switch Tenders only for a few seconds then remove it. Try that and see if it works. Run a few trains both ways through the turnout to make sure they don't pick the points with the power off.

[MisterBeasley]

A 1-amp supply shouldn't cost more than about $15.  Remember that besides the stall current times 10, you'll need extra power when one of the motors is active.

[pathvet9]

I am showing my newbie status now with this question - where does one turn to find cheap power sources like the 1A that MisterBeasley is talking about?  I do not see them advertised, only supplies like Tony's 5A for ~$40?

[pathvet9]

Seamonster - great point, poor pun! How does one accomplish that?

I would assume by using the suggested 3PDT switches and using the center off position?  

[cacole]

 Check on-line sources such as All Electronics at http://www.allelectronics.com

[pathvet9]

Cacole - thanks for the link. I looked and find this one really cheap.

http://www.allelectronics.com/make-a-store/item/PS-12151/12VDC-1.5A-SWITCHING-POWER-SUPPLY/1.html

Now, I assume that I can cut off the coax plug for hard wiring..... or does one also buy some sort of plug adapter to take the power supply to a terminal block?

 

[cacole]

 You can cut off the plug, strip the wires, and connect it to a terminal strip or whatever you need to do.  Their data tells you that the center is positive.

My personal preference is to use a computer power supply for turnouts, signals, road crossing flashers, sound effect modules, building lights, etc.  One of these gives you +-12VDC regulated, +-5VDC, and sometimes other voltages.  And they have a high amperage output so you don't have to worry about overloading one.

[Texas Zepher]

pathvet9

I do not have an amp meter, only a cheap multimeter

One of the settings for a multimeter should be DC amps. 

If not Harbor Tools regularly has really cool meters on sale for $2.50.  There is no excuse for a MR not to have an electronic meter. 

Am I  correct in assuming that if I use these switches, there will always be a current draw on each as they hold the points in position. Thus, if the rating is 65mA, that is always being drawn as the switch is active? So, 65x10 is the minimum amperage that would work?

exactly. But to me that seems like a way high number.  I use a couple different brands of stall motors and neither of them pull that much.

On the other hand.  For years and years our club has been using a stall motors (both tortoise and some other brand) without constant current being applied.  That is we have momentary contact buttons that apply the power until the turnout throws all the way over and then it turns off.  They don't relax that much. 

[PA&ERR]

pathvet9

I am showing my newbie status now with this question - where does one turn to find cheap power sources like the 1A that MisterBeasley is talking about?  I do not see them advertised, only supplies like Tony's 5A for ~$40?

 

Why not just go to a train show and pick up a second hand MRC (or similar) DC power pack? With the big paradigm shift to DCC (sorry, I just wanted an excuse to use the word "paradigm") you can find those old reliable beasts pretty cheap. Their aux DC out put should have enough power for you!

-Kosmo