Can anyone suggest a power supply for the turntable? Walthers says l5 V 500 mA w/ a range of 12-19 V.
I have an old Tyco transformer w/ 20V AC accessory outputs (appears to have a 300 mA output if my calculations are correct). can i step it down using inline resistors?
thanks for your help!
As far as I know the motor on the turntable is DC. If that's the case the accessory terminals on the Tyco pack won't work with it. The DC terminals would work but you'll have to check it with a meter to see how far it needs to be turned up to get the right power range.
Dr. Frankendiesel aka Scott Running BearSpace Mouse for president!15 year veteran fire fighterCollector of Apple //e'sRunning Bear EnterprisesHistory Channel Club life member.beatus homo qui invenit sapientiam
Jeff, you are right in saying the motor is DC. But the instructions call for an AC power supply. There is probably a rectifier in the electronics somewhere.
As to the original poster, I wouldn't fuss around with the old power pack. AC output power adapters are available at many electronics stores, including Radio Shack.
Unless the instructions have changed since I installed my 90'er six years ago, the range is what is important for the voltage, and so is the upper limit for the amps that the power supply will submit to the turntable. What is apparently unimporant is the choice of DC or AC. Either one is okay.
That said, about three years back, someone began to have trouble with his turntable, the indexed (built-up) one, and it turned out he had a DC power supply. He changed to an AC one and we understood that his problems went away. I don't know if anyone reading will remember this. In any event, I found a used one at a local electronics supply shop that was an AC one. It was 16.5 volts and provided only the maximum amperage specified.
However, my point in posting is that my instructions state they you may use both DC and AC, your choice of one or the other.
I will defer to the electronics wizards here about the resistors. Personally, I think it should work, but I would find it untidy. I would call around to electronics supplies shops for electricians and see if you can hook one that works as built.
Crandell
If it calls for AC, then I would use an AC power supply and not tempt fate. Since the internal power circuit clearly has a rectifier (not only the motor, the electronics DEFINITELY require DC), a DC supply SHOULD work. But what happens I think is if you go to close tot he low range with a DC supply, the additional diode drops in the rectifier result in a voltage to the internals that is too low for reliable operation. When you feed sine way AC to a bridge rectifier and filter capacitor, you actually get the peak out in DC, not the commonly stated RMS voltage. SO all else being equal, for the same voltage input AC or DC, the interals will get a higher voltage with the AC supply. That's the technical reasoning behind "if the manual says x volts AC, use that, don't try to cheap out." You cna find many different power supplies at Radio Shack, among other palces, They probbaly have one matching the specifications listed in the manual. More amps is not bad, if the instructions say, for example, 300ma, a 500ma power supply is just fine. Amps are forced into a circuit, the circuit draws however many amps it needs. Volts do push, so you can;t use a 20V power supply hwere a 12V one is specified, something will burn up.
Ah, my first chance to trot out this golden oldie, which shows the relationship between volta, smps, and ohms:
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
way cute!
my old tyco is a 6VA transformer that sends out 20 volts AC for 300 mAmps. walthers says to use 12-19 volts w/ 500 MAmps. so my concern was using the 20V push. talked to one of my rr buds who is an elect engineer and he said don't sweat it - the initial draw will pull it down 3 V or so.
anyway, it seems to work fine.
i did a online check but thought someone might know an inexpensive site for a simple power source - that's what i'm looking for. will travel back to Amherst RR show in late Jan and should be able to find something there.
thanks all for your responses. cheers, john,
modeling the GN skykomish (sky) yard in the 50's.,