I have a db 150 and a adjustable power source what setting is right for a HO layout
Thanks
You need 120v AC and a max of 5 amps if you want to ball-park the power supply I purchased from Digitrax for my DB150.
As for what to supply your rails, on the front of the DB150 are small two toggles. The left-most one should be in the “HO” position.
Crandell
If you mean the power supply feeding the DB150 - around 15V AC or of it’s the PS514, set it to the 16.8V DC setting.
Set the ‘scale’ switch on the front of the DB150 to HO.
–Randy
Randy, if he wants to run strictly HO, I would agree with 15 volts maximum for safety. If he were to want all the possible voltages offered via toggle settings, including O gauge, he would want a power supply with a throughput of up to 17-20 volts would he not? This is just an academic question because he clearly wants only a capability in HO. So, it would be 120 volt input with 15 output to run HO well, but if he wanted the O scale capacity, it would have to provide a higher in put and let the toggle do the voltage regulation?
Crandell
Well, he DID say HO…
Yes, if you are using the N scale setting, the switch on a PS514 should be set to 13.8V DC, for the O scale setting, probably the 20V DC setting would be appropriate.
Other multiple option power supplies are likely similar - in fact all the PS514 is, is an adjustable laptop replacement power supply, which is why it comes with those extra tips which aren;t needed, and has the multiple voltage settings. The highest setting of 24 volts exceeds what Digitrax recommends for a maximum input power, even.
Rule of thumb, due to the fact that the Digitrax boosters have a diode bridge on the input, is for AC voltage, use about what the expected track power is - ie, the HO setting puts about 15V to the rails, so use a 15V AC power supply. For DC, you need to compensate for the two diode drop through the bridge, so you want around 1.4V higher than the expected output. You CAN use the maximim input voltage allowed while setting the track output to the N scale setting, however the excess voltage is all wasted as heat and will reduce the current output capacity, and/or cause the booster to shut down from overheating. For most efficient operation, you want to run the input as close to the expected output, without droppign below the expected output. The less the booster has to reduce the voltage, the cooler it will run. Same applies to using voltage regulators to wire lights in structures and so forth - sure a 1.2V regulator can work with a 12V input, but it will be far more efficient with say a 3V input.
–Randy
Thanks, Randy. The power supply for my DB150, purchased from Digitrax, is 120 volt input, and I don’t know what its output is, but it must be able to supply the voltage that the large scale would need ideally if that scale were selected by the user. I was just curious how that works, supplying the maxium, and how the toggle position limits the voltage to 15 volts, plus or minus a volt, and the 20 volts if O were selected…
Crandell
The one they used to sel, the PS15, is fixed 15VAC. However, with a rectifier and filter capacitor in the power supply, this ends up at about 20V peak, so it’s enough for the O/G scale setting, and a bit too much for the N scale setting. To get away from big heavy transformers (expensive to ship and have to be different for countries with other than 120VAC house current), they’ve switched to what is basically a laptop power supply which is universal input, 100-240 volts, so you only need the proper plug, and it’s a DC output switching power supply so it’s not so heavy, and more efficient. The one they sourced as the PS514 has a selectable output voltage so you can use whatever is best for your scale setting. NCE’s new booster also comes with a similar laptop type power supply, the old transformers are going away everywhere. Same thing with the boosters Tam Valley sells - the power supplies they have are also laptop or LCD monitor supplies.
–Randy