# Powering solenoids with DC ?



## Brakeman Jake (Mar 8, 2009)

I have a bunch of Snap Relays (Atlas 200) that I intend to use in parallel with Peco PL-10 turnout solenoids.Both manufacturers recommend 16VAC for power.I've tested both with a 13.8 VDC power supply and they throw just fine.Anything wrong powering coils with DC?


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## CTValleyRR (Jul 26, 2014)

Nope. I did it on my old layout for years.


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## DonR (Oct 18, 2012)

I have more than 20 Peco Insulfrog turnouts with
their twin coil motors. They get DC current through
a Capacitor Discharge Unit. 

I would strongly advise that you do the same to
protect the coils from accidentally 'long' button
pushes.

Don


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## Brakeman Jake (Mar 8, 2009)

I did some testing a while ago with a CDU I built from Internet plans and found the CDU to be too violent for the Snap Relays.These things don't have a centering spring like the PL10s and have a tendency to frequently bounce out of position,making this unreliable.I want to use these relays (have a bunch of them) in parallel with the PL10s to power position indicators and frog powering (if needed).

Wanting to keep it simple as can be,I'll be using strong momentary center off toggle switch.I'm aware of the coil burning issue but won't be using the Atlas switches that have a tendency to stick occasionally and since I'll be the lone operator on my layout,I should be OK.


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## DonR (Oct 18, 2012)

I'm using a standard home door bell transformer as
my low voltage AC source. I believe it puts out
around 18 volts. Even with that my
PL10s snap the Peco points normally. What input voltage
were you using for your CDU?

But then, the Pecos use a locking spring on the points
and they don't bounce.

Don


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## Brakeman Jake (Mar 8, 2009)

The CDU used a 24VAC transfo for power,I didn't check the output voltage though.The layout wasn't near completion then,so I simply put it away.

The Atlas Snap Relays are easy to use.They're DPDT wich is nice.However,not having a centering spring is a flaw,to a point that Atlas warn to not install them vertically as layout vibrations alone may throw them off.


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## Lemonhawk (Sep 24, 2013)

I have to agree the a CDU is the way to go but its at 24 volts I can see it really blasting away. Don - any recommendations on a CDU that's a little "gentler".


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## gunrunnerjohn (Nov 10, 2010)

Remember, solenoids have different designs and will operate differently on DC than AC. For AC the impedance and resistance are in play, for DC it's pure resistance. I've found some don't react to DC all that well and draw excessive current before they will actuate, so I'd do a few bench tests.


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## Brakeman Jake (Mar 8, 2009)

I'll complete the installation of a double crossover (4 PL-10s+1 relay) with a momentary switch and see how it works with my DC power supply.If it won't work right,the PS is the easy swap.


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## DonR (Oct 18, 2012)

A CDU is simply a capacitor with a quick recharge
circuit. The cap holds a specific charge, enough for
one pulse to a twin coil motor. That pulse will be
just slightly less than the input voltage. 

I don't think there is that much difference between
CDUs. I think the problem is the 24 volt input. That
would mean the coils were getting 20 + volts.
They would 'snap spritely' with that juice. Reducing
the input voltage would resolve the point bounce in
my opinion. Most twin coils are designed to thrive
on around 14 volts.

I do have a pair of CDU wiring diagrams that I
can email to anyone who wants to build one. Simple
and easy, maybe 5,00 worth of parts. If you want
it, send me your email address in a PM to me. They're
from a Kalmbach wiring book and copyrighted so I
can't publish them on the Forum.

Don


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## Brakeman Jake (Mar 8, 2009)

Well...it seems I need some help.I have tested powering a PL-10 with my 13,8VDC/10A power supply and it does it just fine,same with a Snap-Relay.But when it comes to powering two PL-10s,it fails miserably.So...here's what I need,if can be:

On my layout,I have two Peco double crossovers wich both carry four PL-10 coils,so I need a CDU that would have the punch to move these four coils in a single jolt.Or I could use a momentary DPDT switch and have two smoother CDUs together for the DCO and use only one for the other turnouts and/or other regular crossovers.

I know I can find CDU plans on Internet,either 12V or 24V powered (AC) but what I'd really appreciate would be to have one (or two) that I could power with 13.8VDC,wich I have a good supply of (12A+10A)on the layout.

I'll still have to figure out how to power my relays (position indicator lights)...may be 3PDT momentary switches,if they exist.One problem at a time for now.


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## Brakeman Jake (Mar 8, 2009)

I was forgetting...what gauge wire do I need? CDU would be forty inches from the turnouts.I suspect my wires may have been too small also during my tests.


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## DonR (Oct 18, 2012)

Jake

You might take a look at the Stapleton 751 D
turnout motor control switch. It can be used
with either twin coil or stall motor systems. It
throws the points and controls panel or track
side LEDs.

I don't understand why your power supply failed
to throw two PL10s. My yard diode matrix system
throws 3 or 4 of them at the push of a single
button using the CDU that I described. Incidentally,
I saw a home door bell transformer at a thrift
store this week, 3.95.

The AC input voltage to a CDU can vary but is
limited by the capacitor's voltage rating. 

Don


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## Brakeman Jake (Mar 8, 2009)

Right now,there are facts I know but also things I don't,too many "unsure's".I believe my wiring was too small to start with and possibly my switches too.I wanted to use DC to use what's already on the layout but may not have a choice to use the CDU route.Budget isn't great so I'll try to go with the stuff I already have.

I'll first rewire my TO motors with beefier wires then reassemble the circuit,testing as I add components.It should allow me to find the weak element.


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## Brakeman Jake (Mar 8, 2009)

So far so good...I replaced the wiring with four feet of 16 Ga. wires and all four PL-10 shift real nice,no hesitation whatsoever.They lock on both sides every time.And the power supply still has some leftover to drive my Snap Relay,Great!

So now I know two things....my wiring was sloppy and my power supply can get the job done.Next is checking my switch setup...likely tonight...no Blue Jays on TV.....


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