Voltage Levels


D&J RailRoad

D&J RailRoad

Professor of HO
I'm tryin to bring all boosters on my layout to the same voltage level but apparently Digitrax designed them so you can't mix older and new boosters.
My DB150s will adjust up to about 12.8VAC at the track, but my DB200 with Opto Isolators will only adjust down to 13.5VAC at the track. That's powering them off the same PS2012. Yeah, I know about the little POT inside the box to make the adjustment.
If I want to have the track voltages match, guess what? Oh, I'm sorry, you'll have to buy more DB200s.
 
That's a pain. It sounds like the DB150 was under-engineered from the get-go, or something else has gone wrong over the years. I still use my original DB150 and the Digitrax-supplied power supply they sold separately at the time, and so far they work well. I haven't metered my power supply to see if it is still performing like new. Apparently they don't over time.
 
The two variants of DBs measure the same different voltages off the same power supply. That means, two DB200s and two DB150s all wired to the PS2012 at the same time with about 18" of #14 stranded cable show the two different track outputs. I tried flipping the power input to each DB. The track output was oriented properly, i.e. rail A/rail B.
Good marketing scheme by Digitrax.
 
You must get a little bit of a speed variation when it changes boosters, after all it outputs a percentage of voltage level in the DCC waveform, not an absolute level .. The older boosters do not follow the NMRA guidelines very well, as you are supposed to have 12 volts after the decoder, which means 13.5 volts on the track ..
This can easily be seen with a bridge rectifier on the track, and then measuring DC voltage, which should be 12 volts for HO scale ..
 
Actually, a lot of the decoders will take the voltage variations in stride as they cross over the gaps from one power district to another except for BLI models. They claim to strictly comply with NMRA DCC specs. When a BLI loco hits the gap, it will stop and reboot itself. Nice, huh. That's strict compliance in action and that's why I don't buy BLI models anymore.
 
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