Variable Voltage DC Power Supply

Why not just use a HO power pack.

I suspect that unit is for something like a test bench where one would set the voltage  and leave it set for long periods.

@romiller49 posted:

Why not just use a HO power pack.

Rod - That is worth looking into.

The power supply that I described in my original post, costs $19.95. That's pretty affordable. Recently, I have been putting train sets together for my grandchildren, and the children of my nieces and nephews. I have been buying old Lionel and Marx stuff from the bargain bins at the local train shows, fixing it up and sending it off - usually with one of the cheap $19.95 power supplies, or with an original Lionel transformer - if I can find a working one at a reasonable price.

@Mossback Mike posted:

Rod - That is worth looking into.

The power supply that I described in my original post, costs $19.95. That's pretty affordable. Recently, I have been putting train sets together for my grandchildren, and the children of my nieces and nephews. I have been buying old Lionel and Marx stuff from the bargain bins at the local train shows, fixing it up and sending it off - usually with one of the cheap $19.95 power supplies, or with an original Lionel transformer - if I can find a working one at a reasonable price.

Mike, I get these HO power packs at train shows for $15.00 or less. The accessory terminals are AC approx 17 volt and the variable side is DC volt 0-13

Very cool. I like the potentiometer. Should throw a guitar knob on top of it

@MattD87 posted:

Very cool. I like the potentiometer. Should throw a guitar knob on top of it

I bought a package of three pots which included the knobs, washers and hex nuts. So eventually, when I get the power supply installed in a new enclosure, the pot will get a knob job.

@romiller49 posted:

Mike, I get these HO power packs at train shows for $15.00 or less. The accessory terminals are AC approx 17 volt and the variable side is DC volt 0-13

That's a great tip. I'll definitely have to look for one of these at the next train show - which for me will be in St Albans Vermont on March 11th.

Here is a video showing the repair experiment.

@Mossback Mike, I'm not the electrical expert as are a few others on this forum (who I have learned some things from), but I do run my layout on DC current. My reason for this was quite accidental. While adding weight to a 1990's era Industrial Switcher with a DC can motor, I shorted the circuit board reverse. Well, without the circuit board I could add easily add more weight, but to have forward and reverse operation, I'd need to have DC current.

In the early 1990's, Lionel made a rectifier box for the purpose of using a normal Lionel transformer to run their line of G gauge trains that ran on DC current only. So I made my own version of this, adding a heat sink and air slats in the housing for ventilation.

I use a Lionel 1033 transformer which has the unusual feature of differing voltages to the track. The B-U setting of 0-11 volts is perfect for the modern era starter set variety of engines which have smaller truck mounted DC can motors. Whether in sets or as individual sale, these locos were advertised as being AC/DC compatible.

I at one time had experimented with the HO power packs mentioned above. Most of the black box/red handle variety (also the kind that came in the DC only starter sets) have a starting voltage of 6 volts, which makes these locos take off like jack-rabbits. Bachmann had a nice little DC power pack which I tried, BUT these DC power packs DO NOT have the amperage to run much more than one of these starter set locos and maybe one lighted caboose. Add more to the track and the power pack trips. It certainly wouldn't have the power to run an open frame AC motored loco or probably a loco with larger vertically mounted DC motors.

There are also some other liabilities using DC current. There are some Lionel locos, like with "Trainsounds" where you will ruin the circuit boards if you run them on DC current.

Engines with AC motors, like the ones seen in your video Mike, will also get HOTTER much quicker on DC current... this is something to be well aware of. I've read about this on the forum and it is indeed true. You could warp the plastic shell on your engines (those that have plastic versus die cast). I can't imagine getting so hot is good for the engine motor either. So I run MPC era locos for either shorter stints, or I have my layout set up to go back to AC current to the track and will run locos with open frame AC motors on AC.

The heat factor is also true of accessories with solenoid activation, like a crossing gate. I run my not off track power, but off secondary DC power (no buzzing noise) with a momentary push button for activation. At one time I had one wired to a toggle on/off switch so I didn't have to hold while the train passes. Once, I inadvertently left it on, and it didn't take very long to overheat and burn out the solenoid coil. Again, be forewarned of this. Normally I don't activate a crossing gate every time a train passes. So DC current for occasional operation like this is this is fine, just make sure you use a momentary button.

Also some operating cars will NOT operate on DC current. I have the post war operating merchandise car, operating milk car, and operating barrel car: All operate fine on DC current. The solenoid driven operating search light car does NOT: The light housing does not rotate. This is true of the postwar Lionel and the modern MTH versions.

Another liability which I've read about on this forum, is that DC current seems to attract dirt and grime to the rails. One of the electrical experts here explained it, but I couldn't repeat it. I do know though, that it is true. I clean my track a little more frequently on DC current than I ever had to on AC current.

But I find the types of locos I have run more smoothly on DC current, and with the smaller locos, not having the circuit board inside allows more room for added weight, so those locos not only run better but can pull a decent length train.

@brianel_k-lineguy posted:

@Mossback Mike, I'm not the electrical expert as are a few others on this forum (who I have learned some things from), but I do run my layout on DC current. My reason for this was quite accidental. While adding weight to a 1990's era Industrial Switcher with a DC can motor, I shorted the circuit board reverse. Well, without the circuit board I could add easily add more weight, but to have forward and reverse operation, I'd need to have DC current.................

Brian - Thanks for the tips. I checked out your repaint thread. Amazing workmanship. IRT the power supply, I am probably just going to end up using it for accessories. I certainly have enough Lionel transformers kicking around for my old trains. However, I spent $19.95 on the variable voltage DC power supply, and it didn't last more than a couple of months - so I have to get my money's worth. That's why I decided it might be fun to try and fix it.

If you have an old PC Tower laying around not in use, take out the power supply unit and use that for a DC Power Supply. They have 3.3, 5, 12 volt outputs, some have a -12 volt output. You could put a pot in line on a output so you can have a variable power supply. If you use +12 for your positive and do have -12 also, use that for your negative and you can adjust with a pot from 0 to 24 Volts. I'm not sure what pot you would need. I use the 3.3, 5, and 12 volt outputs on my train layout for DC Accessories and Lighting.

I have a pair of these on my bench, they provide pure power up to 150 watts with precise voltage and current measurement.

John,

Nice.   Very nice.

Thanks for posting.  They are just the type that I was looking for.

I've now added one to my Christmas list -- hopefully I'll find it in my stocking, hung by the fireplace with care, on Christmas morning.

Mike

Very nice gunrunnerjohn, perfect for the professional technician like you who needs and demands accuracy with all the complex projects you make in advances to our train hobby. I figured it was probably way out of my price range, not bad at all, only $69.99 on the A website, I thought it would be much more expensive.  Unfortunately all our medical issues, appts, testing, meds, and travel to the big city for our care come first.  That's why I only have a fairly small conventional power layout with starter set trains. But I can dream can't I?😁

@gunrunnerjohn posted:

I have a pair of these on my bench, they provide pure power up to 150 watts with precise voltage and current measurement.

How durable are the pots? That seems to be the achilies heel of variable DC power supplies.

@Mossback Mike posted:

How durable are the pots? That seems to be the achilies heel of variable DC power supplies.

They're not pots, they're digital encoders to set the voltage and current limits.

@gunrunnerjohn posted:

They're not pots, they're digital encoders to set the voltage and current limits.

I am rtfm right now. I should have done that first before making my last post ;-)

It looks really nice, and a decent price - around $70.

How are you using it?

I use them for powering projects on the bench as well as testing smoke units, etc.  For most uses, they're probably overkill, but I really like them.  I've checked the accuracy of the voltage and current readings, and once you get past about 10-15 milliamps, both meters are spot on.   I really like the wattmeter feature, as well as the current limit.  They'll either trip on an overcurrent or go into constant current mode, that's programmable.  There's also an upgraded model with a computer interface to set parameters and read back the status of the power supply.