I'm at the stage now where I'm finally looking to wire up my control panel and I'm looking for some advice as to if that I'd envisioned is actually practical. My motive power is a mix of DCC and analog so I'm using a 24 year old MRC Tech II (which has been in storage the last 20 years while I was travelling the world) and a MRC Prodigy II. My first thought was to have both power leads coming in to a single DPDT switch and from there to the 10-11 DPDT block switches. I'd like panel lights for each of the block and have a bunch of Minitronics 5mm lights and 470-ohm resistors. Lights are going to be handled by a completely seperate cheap MRC powerpack, and I'd like to use leds for thier long life compared to bulbs, but I was thinking of running them off the DC terminals so I could dial up and down the lighting. I'm using Kato N-scale switches and was planning to run them off a mix of Switch-Kats (to support LED signals) and DS64s (?) (which don't support signals). Are there any potential problems if I'm running analog and trying to switch with DCC. An alternative is analog panel control through Ken Stapleton's 751k design. (which I'm considering for many of my switches since I've some 64 turnouts.) Now is there anything I'm missing or any warnings I should be aware of. I do appreciate any input cheers Mike D.
Krasny: I'm going to take the liberty of movng this to the Electrical and DCC forum. I don't have any answers for you, but those guys watch this type of stuff all the time. I'll leave a link for a few days here.
A bit risky. Changing from DC to DCC should involve taking all your DC off and putting the DCC stuff on (and vice-verky). While most modern locos won't suffer unduly being given the wrong kind of volts, some might, so I'd suggest making the actual power change a bit more difficult than (accidentally perhaps) flipping a switch. A switch with a flip up cover or a plug and socket arrangement would be my choice.
It's a bit risky, but not that risky. We have DCC as just another "cab" at the club; we run both DC and DCC at the same time, with block selectors. While we've had a couple "incidents", they have been few and far between. And believe me, it's not for lack of "operator error." (We have a couple knives in the club that aren't so sharp, if you follow me.) We do have rotary block selectors, which are hard to flip by accident. I believe that the most serious incident involved a DC locomotive with some fancy Richmond Controls lighting. (Yes, it over ran a block boundary into DCC power and there was some smoke, I understand. I wasn't there.) As a result we've instituted "Analog Only" and "DCC Only" days, but that's only half the time, and was partly because some of the DCC guys wanted to enjoy the advantage of not flipping block selector switches. Unless your DC locos or passenger cars have fancy stuff installed, I wouldn't be paranoid about running them at the same time. Just careful.
Just to clarify...You are going to use only one type of power at a time? That's what the first DPDT switch is for? And the block switches are simply on/off switches, with one pole for power and the other for the light? eh..could be pitfalls here, and I don't see what makes it worth it. (LEDs are sort of dimmable, but not in a satisfying way, IMO.) If you go this route, make sure you know what the max voltage you are really going to get is. Otherwise your resistors may not be adequate and you could fry some LEDs.
Ben Thanks for the reply. Yes, the first Switch is just to select which power. The second series is blocks (more for analog than DCC) and are simply on/off. No here is where I'm getting technical. 1) Is it alright to have the control power leds run sometimes by DC and other times by DCC (assuming an appropriate resistor (ie 560 ohm, I think the 470 ohm one provided by Minitronics may be a little light for the DCC output). Does powering LEDS with DCC require a bridge rectifier? 2) Assuming I using Analog, can I still run DCC (which does not feed to the track since the 1st DPDT is either/or) to power the DS52 or switch-kat without burning out either decoders or unitrack switches?
DCC is basically an AC voltage, so you need at least a diode in line with the LED. If the DC is always the same polarity the same would apply, but if not then a bridge rectifier will do nicely for both DC and DCC. However ... from what you say it sounds like you are going to run the lights off the 'track' power, which may be DCC or DC as you've said. That means when on DC the lamps will only work (variably) when you have the train controller turned up, which is a bit useless I'd think. (If you are using separate contacts on the switches to work the lights, I don't see the need for the lights to be able to cope with DC or DCC - you can decide which one to use ... period.) Should be OK, but make absolutely sure there are no accidental connections anywhere between any track blocks and the turnout DCC wiring.
I did a feasibility study of doing this on our permanent layout back in its planning stage. This is back when we thought we might want to run DC and DCC locos at the same time. I tested a Lenz LT100 device which is designed to keep DC and DCC from mixing in just the situation you describe. I found they worked as advertised. One would be needed for each DC cab, but it could still be cheap insurance. We ended up not implementing the dual system because of the added cost of block selector switches and extra work involved.
