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Been using them for almost 8 years now along with PH-180s for track power (purchased them a couple years before building a more permanent layout). They always trip before the PH-180s (but to be fair I'm using their 8 amp setting).  8 amps was my initial trial setting when first powering up the track. Nothing has ever exceeded the 8 amps during use so far and I've just left them as first installed.

My layout is command only (DCS and Legacy).  I used most of the PSX's optional features, remote LEDs, alarm, manual reset button, etc. Those are all mounted in the fascia of the layout table near the power cart.  They work quite well and as advertised like GRJ said above. No  electronic failures so far.

I have 4 connected to a ZW postwar for accessories. Three of them on 4 amps and one on 8. I removed D11 since I shorted a couple with a CW 80. In general I use the 36 volt transorbs that GRJ recommends. Maybe the 33s. I have both.

I have the sonic alerts but not installed, seems pointless and noisy since I can see if something goes dark. I forget what reset switch but they are on the boards.

Haven't actually tried the PSX AC circuit protectors, but they do seem like a great product based on forum comments like above from those who know of what they speak.  That being said, I decided to go a different, less expensive route, that by all accounts seems to offer comparable protection at a fraction of the price.  I'm talking about Airpax Instant Hydraulic-Magnetic Breakers paired with TVS Diodes.  One set of each is about $15 - 20 plus shipping.

They work equally well in conventional and command operations.  These breakers trip within 0.1 seconds of overload, have a visual trip indicator, and manual reset.

Here's a link to a recent topic about these Breakers: Airpax Snapac Hydraulic-Magnetic Circuit Breaker

If anyone has done any side by side comparisons between the PSX-AC and the Airpax Instant breakers, I'd really like to know more about your observations.

Last edited by SteveH
@SteveH posted:

If anyone has done any side by side comparisons between the PSX-AC and the Airpax Instant breakers, I'd really like to know more about your observations.

I have not done any comparisons, but the Airpax is reacting in 100 milliseconds. The PSC is microprocessor controlled, it can react in microseconds. Not even close. That's not to say 100 milliseconds isn't fast enough for us.

Last edited by turkey_hollow_rr

I don't have a PSX1-AC to measure but have measured 180 w bricks as well as TMCC Lock Ons. Both open in just over 8 milliseconds which is the time of one half of the 60 hz sine wave. Thats about as fast any breaker can open at 60hz. I would expect the PSX1-AC to be comparable.

That said 100 ms is also likely fast enough since breakers protect the transformer. TVS diodes are what protect the engine and they are much faster.


Dan, thank you for your insight.  That's kinda what I was thinking, that with TVS protection and 100ms disconnect time, there seems to be little chance of any electronics overheating and failing with the Airpax Instant & TVS combo.

[Edit: Norton posted while I was typing] I would also add that if using the PH180 bricks, my understanding is that they also have a very fast built-in microprocessor controlled overload disconnect and would also benefit from supplementary TVS.

With my 2 PW ZWs and a mix of other smaller MPC transformers, choosing the Airpax Instant breakers was a matter of sufficient protection value vs cost.  A savings of over $300.

Anyone else have any side by side comparisons?

Last edited by SteveH

I use a 5 amp resettable breaker in series with 10 amp Airpax on each TIU channel. In a derailment or other short, the Airpax trips first virtually instantly. An overload, such as in my PS 3 MUs when one engine starts in conventional and is a boat anchor, the 5 amp trips first. The Airpax will trip by shorting a 24 awg wire, where the the 5 amp thermal will just melt the wire. Works for me.

Last edited by John H

My PH180 bricks trip instantly on almost any derailment, I'm sure the one or two they didn't trip was simply because I didn't get a short that time.  Although the PSX1-AC looks good, I truthfully don't see the need in my case.

Well you are probably right for your situation but for us with home built power supplies or post war transformers this is the way to go

Last edited by superwarp1

@Windy City

that would be my handy work for the PCB. It was made to hold the 22uh choke that has been recommended for DCS signal when the TIU is used in passive mode. Of course it’s all rated for a full 20A (welding power to some people)


This second Rev I wasn’t impressed with the banana jacks and found some through hole terminals for a decent price and then also soldered the 33.3V TVS diode to the PCB.



Images (2)
  • BCB8314B-4A4C-4A92-A757-C369BD11CFE8
  • 417AC945-9DA6-43C4-80A6-33F2EB5D768C

If you watch my video you will see when I short out the tracks no spark, no arching, no nothing other than the buzzer sounding. I have mine set to 12 amps due to the combo of passenger cars (since converted to LED) and EOB engines which draw lots of current at slow speeds, tends to trip the PSX are lower current settings. When I was using fuses, it would get arch welding all over the place.  With the PSX no more.

Also remember you can get these in one, two, three, or four channel outputs.

Last edited by superwarp1
@superwarp1 posted:

Well you are probably right for your situation but for us with home built power supplies or post war transformers this is the way to go

Even with store-bought power, I think some form of fast-acting protection makes sense, especially if you are running an MTH Z4K. The track power breakers on that transformer are very slow, not even close to the Lionel 180 bricks, which I don't understand since this is a "modern" transformer.

I'm encouraged by those who have installed a PSX-1 AC in their track power circuit(s).  I bought one, but haven't installed it yet because I'm figuring out how to "hide" it inside a trackside building.

To do that, I'll need to extend the LED indicators on the circuit board to an appropriate location on the trackside building within view of the control panel. I bought LEDs from TONY'S TRAINS; one is a steady ON to show that the device is ON, and the other one is a flashing red LED to show a short.  I'll need a reset button too. I'll "pass" on the add-on buzzer.

I intend to install the PSX-1 AC in the track power circuit of my MTH Z1000 "brick," which has a built-in fast-acting circuit breaker; however, I want the extra layer protection for the onboard circuit boards inside a MTH Aerotrain loco.

Has anyone already done this "hidden PSX-1 AC" project? If so, your advice welcome! My e-mail address is in my OGR FORUM profile.

With thanks in advance,
Mike Mottler   LCCA 12394

@rtr12 posted:

Mine are hidden, but on the back of my transformer cart and not on the layout.  But the LEDs and reset buttons are mounted in the fascia of my layout table, remotely from the PSX-ACs.

If you are using a TIU for your MTH Aerotrain you want the PSX-ACs before the TIU (between the Z-1000 and the TIU).

Excellent point. The PSX will not pass the DCS signal. Besides, you want this as close to the power source(s) as possible. Sort of takes care of the "hiding" part.

Are you sure it won't pass the DCS signal?  I have 4 of them (4 loops) installed between the track and the TIU and the DCS signal on each loop works perfectly: 10/10.  I installed them after past  derailments killed a TIU. :-(    Does anybody know for a fact that there is a choke or filter in the PSX-1AC design that should be killing the DCS signal?

Zhubl--rtr12 maintains a forum archive of board layouts and build info for the forum with lots of useful stuff in it. Is there any way that your board design could be added to the archive?


I'd be happy to add this to the list. It's best if the project could be posted in it's own thread with details about it and a few pictures. Then let me know it's ok (preferably from the original poster) to share the information in the list and I'll add it. Please include a link to the thread so I can easily find it. Also, my email is in my profile.

With each project having it's own thread, any discussions, changes, updates, etc. to the project can be posted there and the list will link back to the original thread. That way the projects will always be current.

Hopefully some are getting some good from that list, thanks for the plug.

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