I am planning on building a large layout, 2 level - 14ft x 32ft connected via 2 helixes. I will be using NCE DCC equipment, including PH Pro 5A, 3 mini panels, 11 switch8's controlling 86 tortoise machines with 2 leds per switch as panel indicators.I am calculating approx. 4.1 Amps to run just the mini panels /switch 8's/ tortoise /led indicators.
Here is the breakdown (if I am calculating it right)
86 tortiose @ 22 ma each = 1892 ma (22 ma in stall position)
11 Sw8's @ 80 ma each = 880 ma (80 ma approximate current draw per switch8)
3 -mini P @ 90 ma each = 270 ma (90 ma per mini panel)
172 leds @ 6ma each = 1032 ma (86 * 2 = 172 bicolor leds [2 per switch] drawing 6ma each)
Total = 4074 ma or 4.1A
Question: Should I use a dedicated PB105 to serve all these accessories runningon a separate DCC accessory power bus?Thanks,
RF&Prr I am planning on building a large layout, 2 level - 14ft x 32ft connected via 2 helixes. I will be using NCE DCC equipment, including PH Pro 5A, 3 mini panels, 11 switch8's controlling 86 tortoise machines with 2 leds per switch as panel indicators.I am calculating approx. 4.1 Amps to run just the mini panels /switch 8's/ tortoise /led indicators. Here is the breakdown (if I am calculating it right) 86 tortiose @ 22 ma each = 1892 ma (22 ma in stall position) 11 Sw8's @ 80 ma each = 880 ma (80 ma approximate current draw per switch8) 3 -mini P @ 90 ma each = 270 ma (90 ma per mini panel) 172 leds @ 6ma each = 1032 ma (86 * 2 = 172 bicolor leds [2 per switch] drawing 6ma each) Total = 4074 ma or 4.1A Question: Should I use a dedicated PB105 to serve all these accessories runningon a separate DCC accessory power bus?Thanks,
I don't know what a PB105 is but it appears you are double counting current for the turnouts. If the Switch8s are driving the LEDs, which are in series with the Tortoise controllers then the Switch8 provides the current which powers the LEDs and the Tortoises. In this case I would calculate 20ma per Tortoise and ignore the LEDs, since the same current will flow through them. If you are using separate Switch8 outputs or Tortoise contacts for the LEDs, then you need to count the current.
I use a separate DC power supply for all of my stationary controllers (DS64s), control panels, lighting buses for buildings etc.
Engineer Jeff NS Nut Visit my layout at: http://www.thebinks.com/trains/
Regardless of overall current draw, the Switch-8s at the very least should have a dedicated DCC power district - be that via a circuit breaker or a dedicated booster. If you power the Switch-8s from the same power that runs the rails, and you short out running against a turnout, you'll kill the power that could move the turnout to the opposite position - you'll have to lift the offending loco off the rails to reset power and try again. If there is a dedicate power district or booster, the train will stop, tripping that section's breaker, but the Switch-8's will still have power so you can simply throw the turnout, which will clear the short on the rails, and proceed.
Otherwise Jeff has it right. If those indicator LEDs are in series with the Tortoise motor leads, they don't add to the total current. 20ma is closer to accurate for a stalled Tortoise, and since the LEDs would be in series, the whole circuit will draw that 20ma, not 20ma for the Tortoise plus the current in each LED.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
Randy,
I tested a tortoise stalled at 22ma on 15v dc input.
The Leds are in parallel with tortoises (having a dedicated 2.2k drop resistor), so they will count. I didn't want to risk burnout of my panel Leds if for some crazy reason the tortoise shorts out. Also no voltage drop to the tortoise, so they will run normally slow, but not take forever.
I tested the tortoise with two bicolor Led pairs at 34ma total draw on 15v dc. The switch 8's will handle 50ma per output, so this is well within range.
I have a large yard that has two identical control panels, hence the 2 pairs of leds, one pair for each panel, so you can operate the entire yard from either end. This way both panels show the current switch positions.
Yes, I know having 2 leds per turnout is not typical, but I have rookie operators. I figured that having red and green for each straight or diverging route would be (hopefully) fool proof.
Straight - green =ok, Red =stop
Diverge - green = ok, Red = stop
Of course they will need to pay attention to the control panels while operating their train. (there again, hopefully)
Jeff, A PB105 is NCE's 5A DCC power supply.
Thanks,
RF&PRR
Two sets of LEDs might be a bit much for series wiring, at least witht he Switch-8 and Switch-It, so I can see the parallel wiring. The output voltage of the Switch-Its I experimented with was a good bit less than the DCC track voltage - putting a pair of LEDs in series with the motor slowed it down a lot, wheras feeding the same Tortoise setup with a 12 volt computer pwoer supply via the basic DPDT toggle, the Tortoise still ran plenty fast enough.
I will say I've NEVER seen a Tortoise fail, not any of the one I used, including one I voided the warranty by taking apart because I was curious, and none of the (many more) at the club I use to belong to.
RF&Prr...I have a large yard that has two identical control panels, hence the 2 pairs of leds, one pair for each panel, so you can operate the entire yard from either end. This way both panels show the current switch positions...
CSX RobertRF&Prr...I have a large yard that has two identical control panels, hence the 2 pairs of leds, one pair for each panel, so you can operate the entire yard from either end. This way both panels show the current switch positions... Boy, what a wiring nightmare. When you get it done, you need to post a picture of it.Here are some things to consider:You can cut your LED current draw in half by wiring them in series, still in parallel with the Tortoises, but the two for each turnout in series with each other.As I'm sure you know, the Tortoises have a set of contacts that acts as a DPDT switch. If you have at least one pole of this "switch" available, you could use separate power for the LEDs. If you have both poles available you could use a single DC power supply for the LEDs, but if you have only one pole available, you would need a bipolar DC power supply, two regular DC power supplies, or an AC power supply with steering diodes.The Mini Panels draw current from the command bus, so they would not be needed in the current requirements of an auxillary booster.
I've got over 40 Tortoises wired in series with stationary controllers and switches and I've never had a Tortoise go bad. It's been this way for years. The one advantage of using the Tortoise contacts to control the LEDs is that you get positive confirmation on the mechanical movemement of the Tortoise. Agaim, having never had one fail in close to 9 years, I am not seeing that advantage out weighing the additional wiring involved.
Hi!
I'm a relative newbie to DCC, but not to wiring. I would definitely provide power to turnouts & accessories from a separate power source (i.e. DC powerpack or the like).
Also, given the size of your proposed layout, and if I read correctly, a 5 amp system just doesn't seem to be enough. From my limited experience (I have a 5 amp Superchief plus additional 5 amp booster - each with separate 5 amp power supplies), it seems like you would need perhaps 4 - 5 amp "systems" to give your trains adequate power.
Anyway, for what its worth......
Mobilman44
ENJOY !
Living in southeast Texas, formerly modeling the "postwar" Santa Fe and Illinois Central
mobilman44I would definitely provide power to turnouts & accessories from a separate power source (i.e. DC powerpack or the like).
I've seen others make this suggestion too. However, the NCE Switch-Its and Switch-8s get their "instructions" from the command station. To do this, they must get their power from the power bus. To the best of my knowledge (and subject to correction), there is not any provision with these devices to get their power from any other non-DCC power source. Stationary decoders from other manufacturers may have some other options.
I know from experience that the Lenz LS150 has separate connections for power and command station, and this can support slow-motion machines like the Tortoises.
EDIT: To clarify, I know that the power supply is separate from experience. Given that I use Peco switch motors, I can't vouch for the slow-mo/tortoise capability, but the manufacturer says it can do these devices, IIRC.
The Location: Forests of the Pacific Northwest, OregonThe Year: 1948The Scale: On30The Blog: http://bvlcorr.tumblr.com
The LS-150 can sort of work with Tortoises - it doesn't stay on forever and keep power to the motor. And in using them on a friend's layout we found another issue - if you set it to stay live for say 5 seconds, during that time it will NOT respond to another switch command. So, not really suitable for Tortoises and other stall motor machines.
And even if the power is provided by an external supply, and only command are received from the track bus, you STILL want a seperate power district for the stationary decoders, because if local track power is shorted due to a misaligned turnout, the commands won't get through.