low ac coil voltage relay question

Thread Starter

NatP

Joined Jun 28, 2020
5
Need a low VAC DPDT relay for a model railroad project. When activated (NO contacts Close) a 110v power supply for a sound card turns on.
Low voltage AC relays are generally 18 or 24 vac. My Lionel transformers supply 16vac. The train speed control when set to 12 vac delivers 10-13 vac. This is too much variation for the relay to handle reliably.
I have a YIJIA (that's Y I J I A) model YJ2N-LY, 12 vac but have forgotten how to compute the in-series resistance needed to bring the supply voltage down to coil specifications.
Suggestions for relays and help with the calculation will be most appreciated.
Nat Pulsifer
 

crutschow

Joined Mar 14, 2008
24,966
ES has a good suggestion to convert the AC to DC.
For that you need to determine how much DC voltage you need to reliably operate those 12Vac relays.
Do you have any info on the relay coil operating current and coil resistance?
 

MaxHeadRoom

Joined Jul 18, 2013
20,699
Also with the 12v supply, for DC you just need a bridge, going by the actual voltage output, that would be just right for 12vdc relays, no Cap needed.
You may want to wire a reverse diode or BEMF diode across the coil(s).
Max.
 

Thread Starter

NatP

Joined Jun 28, 2020
5
ES, crutschow and Max-
Thanks for helping solve my problem BUT your suggestions require knowledge way above my paygrade.
ES - I do not have a reliable DC power supply. DC relays require 6 vdc to the coil. My DC power supply puts out 16-18vdc whether on the 'constant' or variable (train speed control) voltage output.

crutschow -I am not finding answers to you questions in the spec sheets; will keep looking.

Max - I am reluctant to mix DC into the already complicated (for me) circuitry.
Thanks to all.
Nat
 

eetech00

Joined Jun 8, 2013
1,897
Need a low VAC DPDT relay for a model railroad project. When activated (NO contacts Close) a 110v power supply for a sound card turns on.
Low voltage AC relays are generally 18 or 24 vac. My Lionel transformers supply 16vac. The train speed control when set to 12 vac delivers 10-13 vac. This is too much variation for the relay to handle reliably.
I have a YIJIA (that's Y I J I A) model YJ2N-LY, 12 vac but have forgotten how to compute the in-series resistance needed to bring the supply voltage down to coil specifications.
Suggestions for relays and help with the calculation will be most appreciated.
Nat Pulsifer
are you sure that isn’t a DC relay?
 

ci139

Joined Jul 11, 2016
1,463
buy no chinese shit without spec.-s (directly shows they don't value the other people , nor their time nor their life (i have a fatality of a close family friend - though somewhat indirect ... but still connected to their "virus program") as those bitches have murdered "half" the planet ... ? "for free" of penalty)

see pg.3 https://www.engineeredair.com/parts/N6JU49837.pdf about https://en.wikipedia.org/wiki/Omron
 
Last edited:

djsfantasi

Joined Apr 11, 2010
6,427
Given that he’s using Lionel transformers, I’m assuming his model trains are Lionel O-27. Track power is 0-16VAC. Relays used with legacy Lionel track are almost always AC. 24VAC relays need around 21VAC to activate, hence probably won’t work reliably.
 

Thread Starter

NatP

Joined Jun 28, 2020
5
Given that he’s using Lionel transformers, I’m assuming his model trains are Lionel O-27. Track power is 0-16VAC. Relays used with legacy Lionel track are almost always AC. 24VAC relays need around 21VAC to activate, hence probably won’t work reliably.
You are correct, sir. O27 gauge 16vac.
I can get 12 volts connecting a separate rheostat to the 16t volt (constant) terminals.
 

ci139

Joined Jul 11, 2016
1,463
the auto-motive relays can "switch" at almost 300Hz ... so i assume the ~AC relays must have a rectifier and a minimal "low pass" built in to actuate smoothly ?
 

crutschow

Joined Mar 14, 2008
24,966
AC relays must have a rectifier and a minimal "low pass" built in to actuate smoothly ?
No.

Here's an explanation of an AC relay coil from Techwalla:

the AC relay has two coils to make a transformer to keep the core magnetized. The wire of the traditional coil is the transformer primary. The secondary of the transformer looks like a D-shaped copper washer or ring. Some of the magnetism from the primary coil produces current inside the copper ring. The current in the ring, or transformer secondary, is actually delayed compared to the current in the primary coil to keep the core always partially magnetized. The lever won't chatter against the core because, while the AC is flowing, the continuously magnetized core never releases it.
 
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