Hi everybody,
Rcently I decided to try and build my own hand held dc throttle. I am using a rotary dimmer swiitch (rehestat is what its made from I think!) to regulate power. Is there a diagram out ther for this kind of thing? I tried running it with both the postive and the negative though the switch. ideas? I am new to wring so any help I can get is appreciated.
Thanks
trainguy700
I'm willing to bet it didn't work ?
Mark.
¡ uʍop ǝpısdn sı ǝɹnʇɐuƃıs ʎɯ 'dlǝɥ
I’m not sure if a AC lighting dimmer switch could lower the voltage enough to work properly.
There are complicated plans for DC walk around controllers with momentum and braking but you need to know how to solider etc. When I was a kid I had both Tyco electric trains and slot cars. I quickly discovered that I could hook up the slot car throttle to the train transformer and use it as a walk around throttle but I still had to use the reverse switch on the transformer to switch directions. Later Tyco came out with their Turbo Train which work the same except they added the reverse switch to the handheld throttle. So if you want a really cheap handheld throttle for DC power just get the Turbo Train throttle and 2X wall wart 22volt transformer from eBay.
P.S. I use CMI Super Blue DC transformers which have walkaround throttles. You might find them on ebay. They are out of production but the same product is made by USA trains. http://www.usatrains.com/usatrainspowerpacks.html
Not a chance it will EVER work. An AC dimmer switch typically uses a triac to switch the voltage ona nd off. As the 'ac' in the name might suggest, a triac will NOT work with DC, it requires AC because it uses the 0 crossing point to switch off. Otherwise, once turned on, it stays on.
Just google DC walkaround, there are many out there you can build. The best types are 2 pieces - the base unit mounted on the layout which contains the power transistor (the part that gets warm in use) and the handheld with the speed control potentiometer and direction switch. That way the handheld stays cool (only very low power to control the transistors flows in the handheld) and you cna use light flexible wire to connect it to the base, making it easier to walk around with. Also this is the type that can have a memory function so you could unplug the controller and move to another location without the train stopping immediately.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
A rheostat I believe was first used many years ago with a big selenium rectifier and a reverse switch. The selenium rectifier would really stink when it whent bad.
A rheostat is essentially a high wattage potentiometer. Pots are usually two watts max and even much less wattage sometimes.
Not easy to find rheostats anymore.
A pot could not handle the average current of a DC motor as far as I know.
The newer Bachmann DC throttles in the white case are ok but the older one in the black case is not the best. I have seen the inside when they go bad.
I built many years ago the Pacematic throttle from a MRR magazine article. I use to have a page with a very similar circuit but it is gone.
It used a 10k pot, darlington pair transistor and a NPN power transistor.
If this is out of you league, you can find a lot of used DC throttles on ebay. Ask here if in doubt about a particular one.
Rich
If you ever fall over in public, pick yourself up and say “sorry it’s been a while since I inhabited a body.” And just walk away.
There are many on ebay.
MRC is a very good DC throttle but ask here first about a particular one. You don't have to show the ebay link, just the MRC model number.
Correct me if I am worng but didn't Allen Mclelland build something like this sometime ago? Just wondering if he ever published a diagram.
In case you are wondering there is a complete circuit with the setup I am using. However somewher in my wiring there is a HUGE loss of power. So much that by the time it gets to the track its almost unmearable with my multi meter. Is there a solution to this problem?
Thanks for everybodies help!
I will keep you posted!(Pun intended)
Trainguy700
Could you use a potentiaometer instead?
Tranguy700
richg1998 There are many on ebay. MRC is a very good DC throttle but ask here first about a particular one. You don't have to show the ebay link, just the MRC model number. Rich
What do you guys think about the
(Just copied the header off their website)
Here is the page on it:http://www.thegmlenterprises.com/id18.html
I see a red flag when I read "* Input power required: 12 to 18 volts AC".
Seems like it is not complete. Also it uses 1/4" stereo jacks which can become loose, intermitten.
Here is the one I recommend http://www.ebay.com/itm/Train-Power-10-Transformer-made-by-USA-Trains-/132006914641?hash=item1ebc39aa51:g:AgEAAOSwXeJYLo7l
It uses phone jacks for secure connections.
Another option which should be considered is from MRC which is the leader in DC train transformers. MRC Throttlepack 9900
http://www.ebay.com/itm/MRC-Throttlepack-9900-0001310-/262721723959?hash=item3d2b6f5e37:g:njkAAOxyLm9TGhY6
and matching remote handheld controler MRC 1325
http://www.ebay.com/itm/NEW-MRC-Throttlepack-9900-9950-Handheld-MRC0001325-/322196907669?hash=item4b046ea695:g:qW0AAOSwtnpXjVCd
There are other sellers selling the same items so check for best price before you buy.
If you are losing power at distant parts of your layout it just meaans you need more feeders. Track and especially the rail joiners make for poor electrical connections. You should run some fairly heavy wire from your power pack, like #14, and tap off feeders to your rails ever 6 feet or so. Bet you won;t have any power loss then.
Yes you use a potentiometer but not by itself, they can;t handle the currnet of a train. The ptoentiometer drives a transistor or series of them which powers the track. If you have poor feeder connections to the rails, a more powerful power pack is not going to fix it. And no, you can;t just use a rheostat. The problem is that modern HO locos draw so little power that with a typical HO rated rheostat they are uncontrollable - they take off at full power when you crack the throttle. An N scale rated rheostat works but then older higher current HO locos won't run. Transistorized is the way to go.
What's wrong with a throttle that takes an AC input? You just power it with the AC terminals of the old fixed power pack. And low current 12V AC wall warts are a dime a dozen.
I can pretty much gurantee I can build a power pack that has a better true power output thatn the MRC 9900 with a walkaround for half the cost of the MRC one. While their stuff is good, it's getting rather expensive and the build quality isn;t what it used to be.
Dig into the January 1970 MR and find the transistor throttle circuit there. Build it. Parts cost even now is probably less than $10.
Disclaimer: This post may contain humor, sarcasm, and/or flatulence.
Michael Mornard
Bringing the North Woods to South Dakota!
That may be too old - the parts specified may no longer be available. Rob Paisley has a bunch of circuits on his page using present day components:
http://home.cogeco.ca/~rpaisley4/Throttles.html
After the power supply is a basic transistor throttle, and right below that is how to add walkabout control to it - of the type I mentioned where the handheld contains none of the heat-generating components. As you scroll down more there are more complex designs including one which makes the handheld unit unpluggable so you can install multiple plug in panels and move around the layout without the train stopping instantly.
Probably easier to use that.For the record, the 2N3055 is a buck and a quarter, and though the TIS92 is hard to find, you can use any NPN transistor that can handle 100ma, which are available anywhere for pennies.