Thinking about another very small loco that is only 4.5 volt. What would I need to operate it on 12 volts?
Since you run regular DC you should be OK as long as you keep the the power low . Anything more than 4.5 volts will probably make it run like a rocket .
I guess it depends on how much you like that 4.5 volt loco........putting it on the track and hoping noone (yourself included) turns the power up. By 6 volts, I'd expect the loco to be emitting realistic smoke.....at least for a few seconds. Locos rated that low generally have pretty delicate wires and it doesn't take much to melt things. Since I'm assuming you are running it on the same track as other locos, your only option is to put a resistor in the loco to drop the voltage .......sort of the same as putting a resistor in the line with LEDs so you don't fry them.
Resistor was the word escaping me which brings me to the next question or questions. Loco is very small thus not a lot of room so size does matter and what type or rating of a resister do I go shopping for?
Within the past two months someone posted about building a controller with a 9 volt battery, a small voltage regulator and a spdt swith. I don't remember his name or where items were purchased. That should work for this. You could put in smaller batteries.
either a resistor, or two sets of diodes would work [on the controller], this would drop to entire track voltage down ..
Not looking to build a controller or to drop the track voltage down. The loco I am looking at is a Tsugawa Yokou 14014 Railroad Track Moter Car TMC100 4957265910048_b65a3b876fb74152964a7d7ae65bacb1__62749.1634111930 by John Moore posted Apr 28, 2022 at 9:30 AM
You can not just add a resistor(s) to the motor to drop the voltage. Motors, unlike LEDs, draw much more current and you will end up with a fairly large (physically) resistor or even a ginormous power resistor. Plus, there is the problem of heat. You'll be needing to dissipate roughly 1 watt of power, which is not trivial. An enclosed shell will create even more issues and you may end up with a melted shell. You can use diodes like wvgca suggested but put them inside the locomotive so you don't drop the entire layout's voltage. But, given that we are in N scale and you'll need a bunch (each diode drops approximately 0.7 volts), it becomes improbable to fit all of them inside the shell. The proper way is to use a voltage regulator, say good for 0.5A. But again, the space inside the shell becomes an issue. If you take a look at the picture Shortround posted, it's not just a single IC even if you eliminate the battery, pot, wires, etc. @John Moore do you plan on running normal 12V locos at the same time as your little switcher?
I have single track main with power routing so only a single lashup at a time on the track. This is a M of W car and I might get two of them. This company has a series of locos that use this mechanism. I may try to build the controller that Shortround pictured above and use three 1.5 volt batteries or option 2 is to determine at what setting my controller is putting out 4.5 volts and mark that on the controller. Only once did I ever use a resistor about 30 years back and I remember its size and the heat. And about the only space in this little critter is the cab.
Lacking a good meter that is simple to operate and will read low voltage down to the decimal point I have corrected that and ordered a simple no frills meter that operates on the low voltages. Getting it through Amazon.
The regulator I've pictured; https://us.amazon.com/WayinTop-Volt...b8281&pd_rd_wg=CFwXV&pd_rd_i=B08BJ4WQCV&psc=1 They also have the switch, battery connector, box, etc.
You can take that idea even farther if you are serious about protecting your engines. Depending on the type of controller, you can add a physical stop so you can't turn the4 knob too far. Drilling a small hole and putting in a little peg can be very effective. Remove the peg when other equipment is running. Alternately, the diode suggestion has potential. You can add several diodes to get to an approx 4.5 V limit to the output of the controller, or across the track somewhere convenient. Add a switch and only turn on the diodes when the small engine is running. Both ideas have the same drawback. You have to remember every time to not turn the knob too far, or switch on the protection diodes. And everyone else around has to remember too. Best to buy an extra one while you can.
Well..........we've established this may be a problem. It sounds like a separate small controller is not an option........and there probably isn't any room in the loco to add any voltage dropping components. An option used in some larger scales is to put things (like batteries, decoders, ect.) in a separate boxcar dedicated to that loco, but I'm not sure that's an option....#1 you may not want to do it, and #2 it would require cutting the pickup to motor connection in the loco, running a wire from the pickup to the car, and then another set of wires from the car, back to the motor, which seems like a lot of work......your call on that. Noone has asked, but I'm assuming you are running DC. How big is your layout? are you running this little loco at the same time as other locos? If this loco will be running by itself, your best bet is to simply go back to the "don't turn the power up" option. There's nothing "wrong" with that option, and if you run by yourself, you can probably get away with it.
I have decided that electrical skills lacking greatly I would probably get into more trouble trying to build a controller. My electrical knowledge is limited to plug it in and flip the switch. That is why I have a become a big fan of Kato's plug and play system and all my turnouts are manual. This little critter is slightly longer than a M of W speeder and with the crane bed there is next to no room under the hood so to speak. And after the discussions here size becomes a big factor in having any room under the shell with maybe the exception of a small space in the cab so diodes and resistors are basically out of the picture as far as having the room to install them. So I have decided that the throttle control is the best option and have ordered a voltage meter that shows 1 to 30 volts and shows decimal points on less than a volt. That will be mounted on the power pack. And thus I have ordered one and a set of trailer cars. They are on EBay but pricey as in over priced. Mine are coming direst from Japan from a major dealer there. Evidently these are extremely popular and so is the mechanism which is sold also, as supplies are running out.
I'm amazed those little cars stay on the track while being pushed thru those tight radius turnouts. Looks like it would be a great little train for a dedicated loop on an N or T track module.
I'm amazed those little cars stay on the track while being pushed thru those tight radius turnouts. Looks like it would be a great little train for a dedicated loop on an N or T track module.
Assuming your DC controller uses PWM, you may not get an accurate reading from a DC voltmeter. But OTOH I'm not sure it matters, as the loco may accept 12v pulses without any issue as long as the feed averages out to 4.5.
