robkozWow. Not much confidence for EB1's.
That was a separate thread(s) where Gary unwittingly reprogrammed his EB1's. It was suggested that could have happened, but he chose to replace them with PSX's. NCE found they were reprogrammed but otherwise working normally.
There is a MRVP series Rehab My Railroad, where a PSX board died and needed replacement. They didn't discuss the whys, but everything can fail at some point.
Henry
COB Potomac & Northern
Shenandoah Valley
robkoz Wow. Not much confidence for EB1's.
Wow. Not much confidence for EB1's.
Where's it say that in this thread? Gary's were not failed, they were in programming mode (which fairly early on in discussing the issue I asked if the jumper was on..).
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
PM-42's break both legs of the protected track section.
Good old relays. Still useful.
PSX-AR should break both legs as well, it has to to be able to reverse (transistors wired as a DPDT switch. The other PSX series though, looks like only one leg, you can see the one big trace go right across the board from the input side to the output side. I also just noticed they have a capacitor across the rail A and rail B traces. Now that's kind of interesting. Wonder if that's to compensate for the inductive factor of the current sense transformer.
Stevert I'm currently (no pun intended) switching over to a Digitrax BXP88 (8-section solid-state circuit breaker with detection and Transponding for each section) and two Digitrax BXPA1's (single-section solid-state circuit breaker with auto-reversing, detection and Transponding) for the reverse loops.
I'm currently (no pun intended) switching over to a Digitrax BXP88 (8-section solid-state circuit breaker with detection and Transponding for each section) and two Digitrax BXPA1's (single-section solid-state circuit breaker with auto-reversing, detection and Transponding) for the reverse loops.
Don - Specializing in layout DC->DCC conversions
Modeling C&O transition era and steel industries There's Nothing Like Big Steam!
I formerly used a PM42, and a pair of AR-1's for the two reverse loops.
The changeover isn't due to any issues with the PM42 or AR-1's; they have worked perfectly for me even since converting to only sound-equipped locos on the layout.
It's simply the easiest and most cost-effective way for me to implement detection for the eventual addition of signaling
hdtvnut I have five psx's here and a psx-ar. Have installed about 10 more in two clubs. One had to be replaced in about 10 years. Light bulbs are not a great idea, because they probably won't work well with multiple units or lighted passenger trains. A bulb with low enough resistance so as not to bog down multple engines can pass quite a bit of current, and overheat damage can occur at the site of a short.
I have five psx's here and a psx-ar. Have installed about 10 more in two clubs. One had to be replaced in about 10 years.
Light bulbs are not a great idea, because they probably won't work well with multiple units or lighted passenger trains. A bulb with low enough resistance so as not to bog down multple engines can pass quite a bit of current, and overheat damage can occur at the site of a short.
Light bulbs are not a great idea, because they probably won't work well with multiple units or lighted passenger trains. A bulb with low enough resistance so as not to bog down multple engines can pass quite a bit of current, and overheat damage can occur at the site of a short. I once put a new Broadway Ltd steamer on the track of a DCC layout without electronic protection, which had an intermittant short of a driver to the shell, and the axle overheated enough in several seconds to melt the driver hub. PSX's are unlikely to let shorted sites overheat, and work fine with sound engines.
BigDaddy BroadwayLion If the lamp lights up the short is still present My stupid question of the day: Why does the lamp only light in the presence of a short?
BroadwayLion If the lamp lights up the short is still present
My stupid question of the day: Why does the lamp only light in the presence of a short?
The lamp does not light without a short because there is no current flowing. During a short current flows from one rail to the other. This current flows through the lamp causing it to light.
I'll vote for PSX. Have a PSX-4 and PSX-AR that were easy to install and have given me no problems for about 3 years now.
Well plenty of people use light bulbs, and advocate for them, as opposed to an actual circuit breaker. So it counts.
There aren't that many options - Old PowerShield, PSX series, EB-1, PM42, and On-Guard. Couple of more DIY ones floating around. And NCE also has the CP6 which is just the whole light bulb thing with lower current light bulbs for the PowerCab.
So much for the circuit breaker survey.
Rich
Alton Junction
Think of a stenosis, or an arterial narrowing due to plaque. That's where all the pressure gets backed up. The filament in the bulb acts like a stenosis; it's highly resistive to the current that the circuit can through-put per the maximimum permitted by the power supply. At low current through-put, the filament might only get warm and glow in far infra-red. A triple consisted diesel set hauling 40 cars up a 2.2% grade might need 1.5 amps. That's substantially below the rating of the tail light bulb, but it might still glow dully in pitch black, or be warm to the touch. It's still passing the demanded amperage that the three can motors need to do their 'work'.
When the metal wheel jams at the frog and bridges two rails that should never touch, the full current rating for the system immediately wants to course through that point. However, back, earlier, nearer the bus, and in line with the wires serving that part of the track system, you soldered or marretted that tail light which will now glow brightly because all that current has to get through it to get past it to where the short is. Remember, we're talking about amperage, not voltage. The voltage is the pressure in the pipe, but the amps are the water that turns the turbine blades...if that analogy works.
This is how I have come to look at the way the tail light bulb works. I only used it on my second layout, and don't currently even need my boxed PSX-AR any more because I won't be using a permanent reversing loop. Instead, I'll rig a reversible crescent of track to meet up with what looks like the stub of an interchange ending at the edge of my yard.
Dick Bronson has a handy trick adding a few cents to the light bulb method but making it much dafer for your equipment - takes advantage of the dual filament bulbs. Initially, current flows through the 2.1 amp filament. If a short occurs, a PTC resistor switches the flow to the lower current filament. .6 amps at 15 volts is only 9 watts, like the large Christmas bulbs, before everything went LED. Those tend to not get too hot to touch. A lot better than 30+ watts.
Well, so far the ballots seem to favor the PSX units, but not in a landslide.
Bear "It's all about having fun."
Onewolf My layout is a simple loop-to-loop. Wrapped up in a three level mushroom design. See sig link.
My layout is a simple loop-to-loop. Wrapped up in a three level mushroom design. See sig link.
I believe simple would be an understatement.....you have an impressively designed layout and I have been following you progress pretty closely.
To answer the OP question, I have used PSX and Digitrax PM-42's (on club layout). I will never ever ever ever ever again use those (the PM-42's). They were not my choice but I got voluntold to install them. They did not mix well with the Lenz system we were using at the time and were an even bigger headache with the inrush current of sound locomotives (mostly Tsunamis).
On my personal layout I have 10 PSX breakers (some were part of a PSX-4, a PSX-2) but I broke them all apart since they live in different areas of the layout. I have two main power points on the layout (the command station/booster and a booster). Each has 5 PSX breakers and a PSX-AR as I have two reverse loops on the layout.
I am a very big fan of the PSX breakers. The only drawback, which sometimes drives me up a wall is the hum of the onboard transformers. The high frequency noise gets to me sometimes.
Functionally they are wonderful. I have run up to 5-6 sound units in a single block, shorted it with a quarter and they all come back up just fine.
I am in the process of building an external display panel to show the status of the blocks and if they are shorted or not. I will say the PSX breakers are worth their price and they are super easy to connect (unlike the PM-42 which is a disaster without an acculites board). They can be daisy chained too for easy installation.
this is from my old layout but as you can see they can be mounted very easily and the daisy chaining (thru screw terminals) makes wiring them a breeze.
Colorado Front Range Railroad: http://www.coloradofrontrangerr.com/
Not stupid at all.
When a short happens, current goes through the roof.With an automotive lightbulb, as the current increases, the wire across the filament heats up. This produces both light and resistence. The resistence keeps your command unit from tripping. And the light lets you know you have a short. Kill two birds with one stone.
Randy, I am electricity challenged. I have a degree in civil engineering and the only courses that ruined my chance of graduating with honors was the first course in electricy and magnatism and Intro to Electrical Engineeringfor Non-EE majors. Kirchoff, Faraday, Ohm, name them all and they are all gobbledygook to me, which is why I rely on people like you to help if I have a problem.
Well, it's not my law, it's Gustav Kirchoff's, from way back in 1845.
It's also the basis for putting a resistor in series with an LED - Ohm's Law lets us calculate the value of the resistor, but Ohm's law need 2 of the 3 terms to solve - voltage, current, or resistence. Know any 2, you can get the other. Voltage we know, but how do we get the current flow through the resistor? Kirchoff again. Now we have voltage and current and can easily calculate the required resistor value. Current is know because per Kirchoff, whatever current flows through the LED MUST also flow through the resistor. And really, we know the voltage also thanks to Kirchoff - the sum of the voltages through loads in series myst add up to the supply voltage. In simple termes, Vled + Vresistor = Vpower supply. The LED voltage is part of the specification of the LED so that is a known value, and hopefully you know what voltage power supply you are running it from.
It's really not difficult to understand, and it makes it pretty obvious how to figure out what resistor is needed for a given LED with a given power supply. Unless the most basic of algebra eludes you - the sort of stuff they teach BEFORE they tell you it even is algebra.
Vled = Vresistor = Vpower supply. I know Vled is 3.5V, and Vpower supply is 12V. How do I get Vresistor? 3.5 + x = 12. or, basic algebra, x=12-3.5, x=8.5 It really is that simple. There are far more complext systems of equations that are much more difficult to solve but we don;t need that stuff for basic model railroading. These simple things cover most cases you will run into with model railroad electronics.
graymattera lamp in series with the track
in series was the part I was missing. Thanks everyone
Randy, I have been leery about the light bulb method ever since I did my research on circuit breakers for my layout, and I do not claim to be an ace electrician. As for Kirchoff's Law, I'll take your word on it.
First, you have to know what a short circuit is. That's then the power goes out, and comes back without going through a reasonable load. A pair of pliers across the track is not a reasonable load. A working loco motor IS a reasonable load.
So, if you leave the plierson the tracks, and the fuse blows, now the circuit is open. It's exactly the same as removing a short chunmk of the wire. If you replace that wire with a light bulb, now you have a circuit again - out to the track, through the pliers, back through the light bulb. The same as connecting a light bulb to the power supply. So the light lights up. Take the pliers off the rails, now there is no current flow because there is a break in the circuit and the light goes out. Like opening a switch, or taking a chunk of wire out of the circuit.
Now keep the light bulb in place, don't repalce the fuse. The loco draws say 1/2 amp. Kirchoff's Laws say all loads in series have the sme current flowing through them. So if 1/2 amp is flowing throught he loco, 1/2 amp is flowing through the lamp. Except the lamp needs something more, like 2.5 amps to light up. So it doesn't light up. The lamp has a very low resistence, so it doesn't drop much of the voltage, and the train runs normally. But if the loco derails and wedges across the rails, and say the right side wheels touch both rails - now we have a short circuit. We're back to your basic power supply, wire, and light bulb circuit. The light bulb turns on. It draws 2.5 amps. Kirchoff again, that means no more than 2.5 amps can flow through the short circuit.
And that's why I think light bulbs as circuit protection is a bad idea. Typical HO DCC voltage is 15 vold. At 2.5 amps, that's 37.5 watts. (15V x 2.5A). 37.5 watts is a pretty decent amount of heat. Enough to melt plastic, for sure.
A REAL circuit breaker actually turns the power off completely. Unless you enable the manual reset option most of them have, it will periodically try to see if the short is cleared, if not, it instantly shuts off again. A fuse is a form of manual reset circuit protection - power won;t come back on until you change the fuse. But if your trains derail a lot, or you run into switches lines against you frequently, you could go broke buying new fuses.
bearman All those components, Onewolf? Your layout must be massive.
All those components, Onewolf? Your layout must be massive.
Modeling an HO gauge freelance version of the Union Pacific Oregon Short Line and the Utah Railway around 1957 in a world where Pirates from the Great Salt Lake founded Ogden, UT.
- Photo album of layout construction -
I've got a PSX-4, which is 4 PSX breaker systems mounted together on one large board. It's always performed well for me. I also have 2 old PS-REV auto-reversers, which have been in service for many years and also function well.
It takes an iron man to play with a toy iron horse.
If you use a automotive 12 volt 12 watt light bulb it will need around 1 amp of current to light bright. A locomotive that pulls say 200ma or 0.2amps through the light bulb will not cause it to light. So you can trouble shoot or even protect a district from excessive current draw with a lamp in series with the track and the power source.
I have eight of the original "Power Shield" breakers (before they added the X in the designation). They have been soldiering along for at least twenty-years. I bought them from Lloy's Toys if that's any indication of their age. Never switched from anything else. These have performed flawlessly.
I added LED remote indicators plus a cut-out switch.
I also have three of the DCC Specialties AR auto reversers and one Digitrax AR-1 reverser.
Cheers! Ed
bearman Henry, check with Allan Gartner's website. He explains it. I cant.
Henry, check with Allan Gartner's website. He explains it. I cant.
I did and it didn't sink in.
He says it has low resistance so it doesn't light. If I take that same bulb and connect it to a battery it lights, doesn't it? What's different about DCC?
I do have a PSX1 because I plan on having additonal power districts. They do fail by the way because the MR staff replace one on the MRVP Rehab my Railroad.