welp… i have been out of the hobby for close to 15 years and just recently rediscovered my love for trains.
now i am weeding out all of my old equipment as it breaks/fails/etc… and it has come time for a new power pack… yet i am unsure of what type i should get. i have had my eyes on the MRC Tech4 dual pack, but it is listed as only putting out 8.5VA per side. is that enough to run two trains with lighted pass cars? i wont be running any scenery from these packs.
im running HO scale. i currently have a Tech II 1300, but that is my only source of power… and i have two tracks to run. i would like the flexibility to run two passenger trains (one per track) plus lighted cars, or some double header frieghters… etc. im just wondering if the 8.5VA would be enough.
To me 8.5VA sounds a bit marginal for what you want to do. It depends somewhat on how many cars and whether the lighting is LED or bulbs and of course number of engines per train.
I have three Tech 2’s and they each comfortably put out 2 amps at 12volts (24VA). I limit current with tail light bulbs and have inline ammeters. (I had to use that EE degree for something useful [:)]
Do you have the option of two seperate packs with better output?
NEW engines (Kato/ Atlas / Genesis/ Stewat / etc.) run on 0.25 amps. Old Athearn BB engines take .5 amps - .75 amps, and double that to combat friction.
Cheapest after-market passenger lighting is aound .5 amps per car. It adds up.
BEST all-around -bang for the buck - is $140 MRC 9500 with a 30 VA rating on closeout for $90. My 2nd choice is a used Tech II with 2.5 amps.
if you are going to run BB engines, illuminateD passenger cars, twin coil switch machines (let alone all 3), 2.5 amps would be my minimum. Forget claims of “running 9 engines”. My Hobbytown Multi drive ran 2.5 amps alone.
yes i do have the option of using 2 packs. i was just looking forward to the convenience of having two throttles in the same box. haha though the Tech 4 200 i checked out puts out 15.5v on the DC side and is listed to have “17VA Total.”
i was always under the assumption that the VA rating on our packs was the COMBINED output of both the DC and AC side. im assuming that the DC and AC share a common output on the transformer and that the AC is just rectified to get the DC output. anyway, i was never really sure how to measure how much load that the pack can handle JUST on the DC side because the wording is confusing to me. if i were to assume the normal equation then the T4-200 can handle a 1A load but not much more than that… however… thats only if i take the DC output into consideration and ignore the AC side.
am i confused by the wording (?) or does that mean that the pack can handle 1.09A TOTAL regardless of which combination of outputs are used? for example if i am using just DC do i have all 1.09A available to me or is it split between the AC and DC sides respectively…
maybe im just thinking about this too much.
btw… i may post a how-to on how to add constant lighting and gyralight to a Bachmann spectrum F40ph if i get enough interest
Saying 8.5 VA is the same as saying 8.5 Watts – and that’s not very much when it comes to lighted passenger cars unless they have LEDs for their interior lighting instead of incandescent bulbs.
The DC Ohms law formula for Power consumed is P=EI, or Power (in Watts) equals Voltage (E) times Current (I); so a passenger car with two 50ma incandescent bulbs would consume 100ma at 12 volts, or 1.2 watts. A locomotive motor drawing 1/2 amp of current at 12 volts would be consuming 6 watts.
Back in the old days the mfg. stated the output in amps. somewhere down the line they changed this to volt/amps…probably to confuse us. I have a Starr-Tec that says 100MV. Which would be 100 millivolts…cant be that because it runs 2 large scale locos outside with ease. The MRC Control master 20 puts out 65 volt/amps which would be a little over 5 amps @ 12 volts + it has a walkaround controller. get the largest you can afford so you wont be in the same situation again. You can even use the Control Master as a power supply for DCC if you decide to convert in the furure… Jerry
I’ve been using the MRC 9500 for about 10 years when the price was $59.00. I run long heavy freights w/2 or 3 diesels pulling. I have never had a slow down of power. Sometimes I run both of my mainlines w/the same power unit w/3 engines on ea. track. It also has momentum, emerg. brake & has track power & amp gages built in. I also have an MRC twin pack & I just bought the MRC walkaround system.
I have a Tech4 280 Dual Control that I use for DC operation. I’ve run three Athearn locos per side at the same time with it. That’s six locos at once. That’s more than twice what the Bachmann EZ-Command can handle.
as it turns out, last night my venerable Railpower 1400 went out on me. i say went out, when in reality it actually went to full voltage and was unable to be throttled. why? well at first i thought the pot was to blame as it was measuring at 7ohms no matter where the wiper was. so i replaced the pot… no dice. then i figured, well maybe the voltage regulator is shot. replaced that, no change. though this time the voltage was actually changing on the Vout, yet not changing at the pack output.
at that point i said “no more” and decided to just build my own…
so i sank back down into the laboratory… i gutted the case, glued and pasted together some old parts… and after adding some electricity i was able to resurrect the old beast!
i dubbed it…
Frankentroller 5000!!
its alive…ALIVE! complete with dual control and glowing red eyes. now i just need to find some cool knobules… or maybe i will just leave the pot shafts like that… it kinda fits the look hahaha
THEORETICALLY 1.5 amps @ 12 volts is 1.5X12= 18 VA. but Don’t count on it.
The capacity of the tansformer determines the Amperage. It is shared output, so the combinedAC and DC load is what counts. That is why trains slow down when 2 or more twin-coil machine buttons are pressed.
Amperage consumption goes up the voltage comes down. A typical Power pack delivers 16 volts at the AC terminals which the is rectified into DC somwhere around 12-0 volts at the DC terminals.
How much power is deing used and how much is left - without meters, you won’t know. “The train runs slow at 90 MPH”(printed on the knob)?
GAPRR’s MRC 9500 has meters. It also is rated at 30VA and is on sale at a closeout price. It’s a Bargain. You can do wiorse - a LOT worse.
One can always use a multimeter to determine amperage draw.
Also, just remember that Watts(W) = Volt-Amps(VA) = Volts(E) * Current(I) in pure DC circuits only. Once you cross over into modulated DC (aka DCC) or AC, then that equation is out the window.
Its been mentioned in several other threads, but I would highly recommend using a regulated 13.6Vdc Power Supply or a converted Computer ATX power supply to run all your switch machines and other accessories. Keep the Locos on a seperate supply.
