I've come up with a easy to build handheld throttle you can build yourself if you have decent soldering skills and a good soldering iron. This control is setup to run from a DC power source up to 18V. Here's the parts you'll need-they should all be in stock at your local radio shack: Qty 1 TIP120 Darlington Transistor #276-2068 $1.29 1 5K Ohm Linear Taper Potentiometer #271-1714 $2.99 1 Project box-if you position everything carefully you can fit it all in a 4x2x1 #270-1802, or use the next larger 5x2x2 $2.69 1 DPDT Center Off toggle switch-I used a large heavy duty #275-1533, the little blue micro switches are nice looking and smaller but the quality is junk, avoid if possible. $3.69 1 330 Ohm Resistor 1/2 watt or larger #271-1113(you'll get a pack of 5 for $.99), color is Orange-Orange-Brown-Gold. 1 Terminal Strip 12 Position #274-680, you can cut these in 1/2 and use them if you want to be able to disconnect the wires from the base. 1 Control Knob of your liking for 1/4" shaft. 6 different colors wire of your choice-use stranded only, not solid core. I used 18ga. Some notes: The views shown in my sloppy sketch show the handheld portion containing potentiometer and toggle, separated from the base which contains the transistor and resistor. ALL VIEWS ARE LOOKING AT THE BACK OF THE COMPONENTS WHERE THE TERMINALS ARE LOCATED. TRANSISTOR IS SHOWN TAB DOWN POSITION. At the base I cut the terminal strip in 1/2, soldered the resistor and wires to the transistor, and secured them into the terminal strip. You are welcome to hard wire everything, or even put everything inside the handheld. The tab on the transistor needs to get attached to a pice of metal to dissapate heat, it will get hot. You can use a piece of aluminum flat stock and screw it to it, or buy a package of R/C car speed control heatsinks that will slide right onto the transistor tab if you get the right kind. It's important that this gets wired right or smoke will be free'd from the transistor or potentiometer. These 2 components are fragile and it's important to use a nice hot soldering iron and make a very quick solder joint so not to overheat the componnet. It's also important that the polarity of the imput voltage stays as shown, so if you will use a power pack as a power supply make sure the direction switch doesn't get changed. I also installed a 12V light(don't use a LED) on the "to track" wiring so that it indicates the unit is working. Toggle switch will control direction and in center off position it's obviously off. I recommend a 3A fuse to be used between this and your power supply as a safety if your supply isn't otherwise protected. Let me know what you think and how yours works. Not to scare you away from this, but here's the standard disclaimer. I'm not a electronics goo-roo and assume no liabilty if you burn your house down electrocute yourself etc. You know how all the lawsuit crap is these days. If you don't know enough about whats described here don't attempt building this. This is easy to build and most of you here should be able to build this with no problems if you can wire a signal or switch machine. Mine works wonderfully and according to the transistor specs gives me up to 5 amps of juice to run my athearn power hogs.
Anyone else tried building one of these? I just hooked min eup to my layout today and I'm pleased they are very smooth and work well.
rkcarguy's original post said that the transistor was good for 5 amps. That may be true, but the 3 amp fuse he recommends will be his limiting factor for available current.
In my non-DCC time I've build my throttles this way. Now I build throttles for DCC. The design is the same: You have a knob for speed, a switch for forward/reverse. The additional buttons are for functions with DCC. Next step, I will solder throttles with 8 functions. Wolfgang
Wolfgang; How do you hook it into your DCC system? How does your system recognize the function buttons and encode them into the DCC stream? I was thinking of building something similar to rkcarguy's unit with two cabs for my Zephyr jump ports. But I'm very interested to know how you build DCC cabs.
I'm sorry, I'm not the DCC guru. I solder only. Some guys at FREMO have developed a throttle. You find information at Digital. Follow the links to your subject. I've soldered about 30 FREDs, now I've ordered 10 FREDIs. Unlike other throttles, FREMO throttles can not choose the engine. You have to get the engine at the central unit and give this engine to the throttle. At a large arrangement nobody can "steal" another engine. Large = 50 engines are runing. BTW, if you don't want to build your own throttle, I would choose the UT4, I own two. Wolfgang
Just being safe. You can upgrade to a larger transistor that will be good for 10 amps but they aren't normally stocked at radio shack. For what I run on my layout I think 3 amps would be sufficent for me and be a safety against frying a transistor.
For H0 3 amps are enough, I think. With more you can run into trouble. I've already seen a molten Kadee axle! With DCC your booster will shut down, very quick. Wolfgang
Be aware that to run at their rated current/power these things usually need to be fitted to a heatsink. Rating can be much lower without.
I actually have it clamped in some vice grips, but I have a heatsink that I will be attaching it to once I get it mounted where I want it.
Bringing my old thread back to life. I recently tested this throttle with over 6 power athearn BB locomotives pulling a 30 car train up my best grade. The transistor got warm but is now heatsink mounted and performed very well. I have eliminated the fuse between the throttle and the tracks, opting for a 5 amp fuse to protect my power supply. FYI the transistors limit is in heat dissapation in wattage, (watts=volts x amps), so if you are running a lower supply voltage you can get away with more amp draw. I did recently find some TIP140 transistors from a elect wholesaler dealing in obsolete parts, so 10 amp capacity here we come. I am also going to attempt building an unplugable memory walkaround "the throttle" shown on another website.
Throttles [digitrax] for DCC are little more then keyboards or mice; they do not have programs operating on them. all the output exits through a phone plug outlet. The electronics side of the hobby is still in the stone age as far as I'm concerned.
Actually, DCC throttles do have programs running on them. For example, with the FRED throttle that Wolfgang was talking about, you can not just solder all of the parts together and expect it to do anything, you also have to download the program for it and write it to the processor. Personally, I don't see how you can look at something like this: and - knowing that this little 1.00" x 0.50" x 0.22" decoder can not only control the high frequency motor output with Bemf compensation option, but also two light outputs(the 1.7" x 0.67" x 0.28" version has four) with several special effects options, such as mars light or gyralight, and 16 bit sound with equalizer, sound mixer, Dynamic Digital Exhaust(changes the exhaust sound in response to changes in load on the motor, such as going up or down hill) and reverb - and make a comment like that, but everyone is welcome to his or her own opinion.
DCC ready...does it have to? My experience with model locos is confined to starter set locos. If a loco is marked as DCC ready, does it have to be ran by DCC or can I run it on my power pack set up? Maybe I'll graduate one day to DCC, but not on todays budget, so don't suggest it, it's not going to happen.
DCC ready does not mean that the loco HAS a decoder, but that it is ready for a decoder to be installed, so you can run it on DC with no worries. If it has a decoder, it will probably say something like "DCC Equipped," or, if it's a Bachmann, "DCC Onboard." Most loco's that come equipped with a decoder will also run fine on DC, although a lot of them don't like pulse power.
You might be talking NCE - in which case the processor is on the throttle. Otherwise, the throttles are little more then input devices. Now why do I say this about modern DCC Throttles? [I'm not even talking about decoders, which is waht you showed - and that too is quite primative] Maybe it's because I look at things like this: And I use this on a daily basis: The electronics inside these badboys makes even that decoder look quite primative. It cannot store large information files; It does not have WIFI/FLASH/USB capabilities. It's nothing more then an input output device. Someday throttles willbe as advanced as my phone. At this point, however, theya re still ten to fifteen years behind the curve.
Benny, I too agree that the elecronics for model RRs are way behind. A WiFi enabled throttle with touch screen input would be awsome. Or how about a small lcd screen in a parlor car that has a scene of passengers interacting with each other. There are endless possibilities. But a huge difference between say Digitrax and any consumer manufacturing company is the amount of capital that can be infused into R&D. Hobby manufacturers just don't have that kind of money. I do think as a community we should be exploring ways to incorporate exsisting technologies into the hobby. I thought using PDAs as throttles showed promise, I think I remember seeing a company that was developing that, but I think that was dropped as PDAs lost populartiy to other devices. I wish I was smart enough to know how to incorparate those things, Eric
I agree, but don't see that as any kind of problem. 1/ Throttles and decoders are only a means to an end for MRRing and represent a fairly small part of most people's train budget - the things you are comparing them to are largely gadgets in their own right. 2/ As a previous poster said, this hobby is a fraction of the size of that for games and phones, so there is even less money to support the cutting edge. 3/ Most MRRs are about 50 years behind the (railway) curve, so 15 year old technology is still futuristic
