Arhi said maybe a L293 Roff says it requires a digital input, won't work?
Yup, mine fingers were faster then my brain. The L293 will do similar thing that you need but with your circuit you can control the output current by changing the input current so your controls are analog. With L293 the output is "off" or "fully on" so the way you control the speed of the motor with L293 is you do PWM (in short, you do a fast on/off with different lenghts of the on and off signal). In order to convert your analog input to generate PWM to drive L293 will probably make the circuit even bigger, and L293 also dissipates some heat...
In short, I think it would not make your circuit better nor smaller.
Now I'll try this again this unit as is works. I wanted it smaller. I was looking as the throttle schematic and it has a L293 on it? I was also thinking I have found many IC that take Analog and convert it to digital. Why would that not work for me If I am sending out analog and I convert it to digital the Dc motor will still work probally better.
https://groups.yahoo.com/group/onboard-keller/files/Throttle/
see if you guys can look at this page. It may enlighten you to something i haven't said? steve
That link ask for me to sign in so I ignored it, but in general, there are a lot of digital train controllers around, but going digital would mean that you have to change bunch of stuff ?! Not sure how is that feasible...
Looking at your schematic, you get the power from the rails (track) and you control the output from brown/orange that comes from T1 or T2 (whatever T1 and T2 are). Now, if you can show us how the "thingy" that outputs T1/T2 looks like, and if that "thingy" can be changed, we might be able to help you replace both the "thingy" that controls the motor speed and this "power pax"...
What I fail to understand is, motor is in the "locomotive", the device you want to "reduce in size" (power pax) is also in locomotive and it is passing trough the current from the tracks to the motor. Now, this part is clear, what is unclear is, where the hack T1/T2 comes from, how do you control this, I do not believe you have some wires sticking out from locomotive going into some joystick
...
If you had only one locomotive on the track you would be able to remove the "power pax" out of the locomotive and power the motor directly from the tracks (as cheap nrc models do) but if you want to have more then one locomotive on the track, the "power pax" has to be in the locomotive, and it has to be controlled by "thingy" that either receives "commands" via RF/IR or trough the modulated signal inside the tracks. Now, as I already mentioned, if you can show us that "thingy" maybe (just maybe) we can make that part digital ..
Before all that, you need to check what "device" can be small enough, control and pass 1A without producing too much heat. The L293 get fairly hot after few hours running ~.5A (without heat sync), you can add heat sync but do you really have room for them / that heat still need to be vented out somehow... If locomotive is made of metal it would be able to use the whole car as a heatsync