PSX1-AC

Really helpful, thank you Gary.

@Windy City - If you do a search for "PSX 1AC" you'll get several topics that mention or discuss the PSX-1AC including how to wire it into your set-up.

A

There's always the instruction sheet...

PSX-AC Manual (PDF)

You really need them for each output of the post war ZW. The ZW-L probably has a fast electronic breaker. Your call there. But the neat thing is that you can set the PSX-1AC units for whatever amount of amps you want the trip.

Sometimes it helps if you do a quick overview of your power setup so the great folks on this forum can better help you.

- Are you conventional only?

- Do you plan to use a command control system?  Legacy, DCS, or both?

- How much power are you putting to the track?  If over 10amps (one PH180 or one channel of the ZW-L) there are additional considerations to think about.

That second question is important because the PSX is known to degrade the DCS signal somewhat so to keep your DCS signal strong you need an additional choke installed.

I have no idea how fast the breakers are on the ZW-L.  If they are as fast as the PH180 that would be great, but the PSX is faster.

The PSX1-AC is also really only for command use, it won't pass low voltages.  From the TIPS section of their site.

The onboard processors derive their power from the input power to the PSX units. To prevent any unpredictable
operation the input voltage should be kept above 10 volts.

@gunrunnerjohn - I take it you can't use J1 to supply an external power source in addition to the AC source?  I'm really surprised you can't feed that board your own DC source.  I'll have to buy one to start poking at it. A

I haven't tried an external supply, but all my reading on the PSX-AC suggests it's really designed for command use.  They started out with a similar design for DCC use.

@gunrunnerjohn posted:

I haven't tried an external supply, but all my reading on the PSX-AC suggests it's really designed for command use.  They started out with a similar design for DCC use.

It looks like to me that half of that board is devoted to rendering a DC supply from the power source.  Also, I would have used a potentiometer to select the overcurrent protection but that would be problematic for some users. A

I appreciate the technical discussion but would like to get back to my original and basic questions: theses issues were not addressed in the instruction manual

Do I need a PSX1-AC with the ZW-L? I was going to use it for my PW-ZW.  Do you recommend it for both?

Can someone share a schematic of how they place and wire the PSX1-AC and TVS, relative to the transformer?

What version of the PSX1-AC is recommended?  Optional LED vs Buzzer?

I have put together 4 "transformers" using the PSX-AC with PowerMasters.  Two use a 360 PM with the PSX set at 15.4 amps, and two use the 180 PM with the PSX set at 8.0 amps.  I also use the TIU passive mode circuit that was (is?) sold by forum member Zachariah Hubl.  The input board has a 22uH choke built in to mitigate the DCS signal interference.

@CAPPilot posted:

Sometimes it helps if you do a quick overview of your power setup so the great folks on this forum can better help you.

- Are you conventional only?

No, mainly TMCC

- Do you plan to use a command control system?  Legacy, DCS, or both?

Legacy not DCS

- How much power are you putting to the track?  If over 10amps (one PH180 or one channel of the ZW-L) there are additional considerations to think about.

I was planning on using a ZW-L, one handle for each of the 4 loops, and a PW-ZW for 2 additional loops, and another PW-ZW for accessories

That second question is important because the PSX is known to degrade the DCS signal somewhat so to keep your DCS signal strong you need an additional choke installed.

Not an issue for me if I use TMCC?

I have no idea how fast the breakers are on the ZW-L.  If they are as fast as the PH180 that would be great, but the PSX is faster.

Can you share a schematic of how youplace and wire the PSX1-AC and TVS, relative to the ZW?

@Windy City posted:

I appreciate the technical discussion but would like to get back to my original and basic questions: theses issues were not addressed in the instruction manual

Do I need a PSX1-AC with the ZW-L? I was going to use it for my PW-ZW.  Do you recommend it for both?

Can someone share a schematic of how they place and wire the PSX1-AC and TVS, relative to the transformer?

What version of the PSX1-AC is recommended?  Optional LED vs Buzzer?

ADDED:  I see you have already answered the questions.

I would use the PSX with both the ZW-L and PW ZW.

I think there is only one version of the PSX-AC.  The others, like PSX-1, are for DC.  I get these from Charles Ro.

The optional LEDs and buzzer just make it easier to know there is a problem.  The PSX will keep trying to reset until the short is cleared, and power will be back on as soon as the short is cleared.  Because of this, as a minimum I would add the reset switch shown in Gary's video to J7 pins 2 and 3.  This way you have control over when power is again applied to the track.

You have not said what your setup is.  Here it is with the TIU in line with track power.  No TIU?  Disregard the TIU and choke in the diagram.

Here is one way to do it with the TIU in passive mode.  Again, no TIU just disregard it and the choke.

@gunrunnerjohn posted:

The PSX1-AC is also really only for command use, it won't pass low voltages.  From the TIPS section of their site.

The onboard processors derive their power from the input power to the PSX units. To prevent any unpredictable
operation the input voltage should be kept above 10 volts.

They should really have these powered by a wallwart instead of track power.  Been meaning to look into this and come up with a mod for these.  Power the device externally and be able to use it in a conventional world.

@superwarp1 - I couldn't agree more to the point I started specking out my own over current protection device.  Something came up immediately in the design...spike current verses over current.  Given the comments about how quickly these units trigger, I suspect they catch spike current.  The issue I  see is that, when starting up a consist of 3 or 4 engines on Atlas track in particular, there will be an inevitable momentary current rush and voltage drop.  I've been debating on whether to design for both of these situations, where the spike current threshold would be offset from the over current threshold.  Just a thought.

Anthony

Anthony, have you looked at the Lionel Powerhouse 180 circuit protection?  It has exactly what you mention, overcurrent and spike current protection.

In the schematic, both U1b and U1c are amplifying the current sense signal.  U1c, the "overload" detector, has a gain of 148, but it is slowed down by the resistor and capacitor on its output.  The time constant (RxC) is 2.6 seconds.  Multiple short hits to this RC combination would charge it up until it trips the relay latch.

U1b has a gain of 37, which means it requires 4 times as much current, but it acts instantaneously for "dead short" situations.

@gunrunnerjohn - I had no idea that the schematic for the PH 180 was even available from the ether.

It might be helpful to list some of my goals and commentary on the matter:

* Instead of using a wire wound transformer (L1), I was going to use a current sense device.  This way there will be absolutely no current draw from the power supply.  However, this method is inherently prone to electric disturbances and anomalies.  So it may not be feasible to do so.

* I would like to be able to transmit the RMS voltage and RMS current to my layout controller.

* If I have the RMS current at my disposable, I can use that signal for the over current protection.

* I also want to be able to set the trip points (no jumpers!).  Not that the PH 180 schematic can't be easily modified to support this.

* I noticed that the value for C4 is not given.  The value of this capacitor is fairly critical.  My guess it's 0.1uF.

* I once worked for a gentlemen with a Masters in Electrical Engineering who couldn't understand the purpose of D2.

* It seems Lionel uses 8V as the default for just about everything it makes with electronics.

Anthony

@superwarp1 posted:

They should really have these powered by a wallwart instead of track power.  Been meaning to look into this and come up with a mod for these.  Power the device externally and be able to use it in a conventional world.

I would be very interested in this.

@A. Wells posted:

It might be helpful to list some of my goals and commentary on the matter:

* Instead of using a wire wound transformer (L1), I was going to use a current sense device.  This way there will be absolutely no current draw from the power supply.  However, this method is inherently prone to electric disturbances and anomalies.  So it may not be feasible to do so.

* I would like to be able to transmit the RMS voltage and RMS current to my layout controller.

* If I have the RMS current at my disposable, I can use that signal for the over current protection.

* I also want to be able to set the trip points (no jumpers!).  Not that the PH 180 schematic can't be easily modified to support this.

How exactly would trip points be set?  For a pure sine wave, RMS isn't a big issue, but if you feed it anything else, coming up with RMS will be a much bigger deal.  From your description, I suspect you're looking at a uP based solution.

* I once worked for a gentlemen with a Masters in Electrical Engineering who couldn't understand the purpose of D2.

Did he also wonder why the switching transistor kept crapping out?

* I noticed that the value for C4 is not given.  The value of this capacitor is fairly critical.  My guess it's 0.1uF.

I'd like to know the value of C3 as well, but it is handy to at least have a schematic.

@gunrunnerjohn -Nope, no uP for critical systems.  However, I will use a uP to do ADC to send to the RF...probably off of a buffered output.  Man, going to make me cough up all my trade secrets.  I'm using a Delta Sigma RMS to DC Converter.  Trip points would be set with potentiometers with detents.  I'd leave C3 out all together.  It's either a remnant or the location of that op-amp requires some signal smoothing or the 8V isn't very clean or I have no idea.  I would have used two capacitors on the 8V regulator output btw. A

I'm guessing the RMS to DC converter probably uses a uP anyway.

I am confused about your statement no uP for critical systems.  What's that all about?  I designed a number of flight critical avionics products that used microprocessors extensively.  These are the kind of systems when it screws up, you likely crash, that's as critical as it gets!  There are so many microprocessors in a modern airplane that it would take me all week to count them.  Somehow I don't see a circuit breaker for a model train layout as being nearly as critical, but maybe that's just me.

@gunrunnerjohn - You'll note I don't fly.  Anyway, the  RMS to DC converter is opamp based "all of the signal processing occurs in circuits with high gain op amps operating closed loop."  And, just so you know, I use 8051's for uPs...much prefer 6502/10's though. A

Wow, talk about old school! I haven't used an 8051 for decades!  I use various Microchip PIC processors nowadays in uP based stuff I do.

Being a long time pilot, and having traveled a great deal in my working life, I can't imagine not flying.   I also didn't have any issue trusting the avionics I developed, the development process is quite rigorous and triple-checked.  I was the project engineer on the very first microprocessor based digital air data computer in 1977 based on the TI 9900 processor.  We developed the uP based ADC for the Boeing 727 for United Airlines to replace the older Honeywell analog air data computers.

I hasten to add, an analog circuit can develop flaws and errors just like anything else.  AAMOF, in some ways it may be less protected as it's possible with digital designs to incorporate self-checking to see if things are going awry in the processing.  Just because it's an analog circuit, that doesn't make it bulletproof.

I couldn’t tell if the OP was planning to also incorporate DCS. If so here’s what I now use for TIU passive mode  

This also covers the TVS diode on the output of the PCB. others also just bend the leads around the output studs of a ZW

If anyone is still interested in the PCB with the choke and TVS I still have some extra send me a email in my Profile

@gunrunnerjohn - I use the Silicon Labs 8051 series.  I've settled on the C8051F39x in particular.  I like being close to the metal and have a very nice task based library I developed for applications. If someone would come over and hold my hand and help me set-up an ARM development environment, I might be inclined to use that.  Otherwise, I can't be bothered with other mcu's. A

Well, I have to say, I don't change on a whim, and since I have all the tools, etc. for the Microchip PIC family, I'll stick with it until there's a good reason to change.

I use a PSX1 for each throttle, Z4000s and PW ZWs. Each has the recommended buzzer installed so that I know when it has tripped. I do not have a ZW-L but run both Legacy and DCS engines. Note that I installed these units after A DCS board failed due to a derailment.

The PSX1-AC is a great product and I highly recommend it.

I have a z-4000 going to a tiu. I power all 4 channels on the tiu by jumpering from the "fixed" inputs to the "variable" inputs then changing the "variable" inputs to "fixed".  I just ordered 2 PSX1-AC's with manual resets and sonalerts. From what I've gathered from the above postings the PSX1-AC's go between the Z-4000 and the tiu. Is the 22uH 34A choke necessary with my setup? If so can someone give me a part #? I looked them up on the Digikey website and there was quite a selection. There might be one better suited for this application.

Any other tips would be helpful

Thanks, Don

If the PSX-AC isn't on the output of the TIU, no choke is needed, it's already supplied by the TIU input circuitry.

GRJ, Thanks for that information. A couple more questions-Does putting the PSX1-AC's between the Z-4000 and tiu protect my locomotives? Are PSX1-AC's fast enough to protect them as well?

There's no absolute protection for electronics, but certainly the PSX-AC in the circuit will help.  A rule of thumb is any electronics surge and/or spike protection is most effective when it's near the device being protected.  However, sometimes that's not all that practical.

GRJ,  I'll try the 2 PSX1-AC's between the Z-4000 and the tiu. If I continue to damage locomotives or tiu's after derailments I'll try a PSX1-AC on every output of my tiu then add chokes. I'm not adverse to buying 2 more PSX1-AC's so I can have one on each output if it better protects my locomotives, but then even with the chokes I'd be worried about signal strength.

Thanks again for your input, I can't learn if I don't ask questions

Don

GRJ,

The above post begs the question: Is a PSX1-AC needed/recommended on a ZW-L?

@gunrunnerjohn posted:

If the PSX-AC isn't on the output of the TIU, no choke is needed, it's already supplied by the TIU input circuitry.

John,

I guess that is the first time I heard that.  While most of my track power has the TIU in passive mode, the power going to the yards goes through the TIU.  I have been putting together PH - PM - PSX - Choke - TIU - TVS/Distribution Block - TVS/track setup.

So I really do not need the chock in this setup?  Plus, an earlier comment by you on the effects of multiple TVSs makes me think I don't need the TVS at the distribution block.  So, this is a better setup?

PH-PM/other transformer - PSX - TIU - DB - TVS/track.

My own testing showed the choke is needed in the TIU passive mode setup, so it is staying.

The choke is useful for passive mode as the power goes directly to the track.  If you are sending the power through the TIU, there is already a choke isolating the transformer from the DCS signal generation circuits.

@Windy City posted:

The above post begs the question: Is a PSX1-AC needed/recommended on a ZW-L?

Not really sure how good the ZW-L is at circuit protection, so I can't say.  Obviously, it's unlikely to hurt anything, just don't know if it offers that much additional protection.

Truthfully, though I recognize that the PSX-AC does provide good protection, sometimes it seems we go a bit overboard with these mitigation measures.  Our modular club has run for many years with the Lionel Powerhouse 180 transformers running a variety of locomotives, both DCS and TMCC/Legacy.  We haven't had any rashes of dead electronics, even though in a portable environment with everything clamped together and the trackwork not 100%, we have our share of derailments and shorts.

My plan on my new layout here is to run with the PH180 transformers feeding the MTH TIU and on to the track.  So far, that's worked fine.

Pretty sure my PSX1s are between the track and the TIU so that the TIUs are protected as well. No issue with DCS signal, as I have 9-10 on the vast majority of the layout.

Scott M,  Guess I'll be buying 2 more PSX1-AC's so I can  have one on all 4 tiu outputs.

Thanks

Don

CAPPilot,

I noted the capacitor in the above drawing.  I thought the capacitor was to bridge any insulated rail joints to preserve the TMCC signal.  Why is it needed for accessories?