The Home Machinist!

I don't know why you couldn't use two identical controllers, one in each engine. Use a dual pot, whatever resistance is required, and run either one cable to the head that will feed both pots, shut offs, etc., or use two seperate cables to go to each engine. Or if you want, use two seperate cables as before and have dual control setups which is what I think you were saying.
Fred

fender, what am i missing here? yes you can use ganged pots...albeit a little crude, but the concept does work. i was speaking to the crowd that was thinking of building an analog control system with a single pot. while i don't want to dim anyone's enthusiasm for electrics, just want to make very sure that all has been thought through before applying main power.

as for not having to run power cables between units, i'm just the opposite. i want a switchable power system that runs all main power to my hands before going to the locos. what many people don't get that with modern pwm controllers is that the motors are constant hot. they only need to see a ground in order to operate. all a runaway needs is an accidental ground. in normal operation, that ground is supplied by the controller...that's how it works. i, for one, don't want to count on the sole operation of a small signal input...i want options. also, if you are going to work on your power system with it turned on, don't. and don't think that just because you turned the system off, it's now safe. oh no! not yet it isn't! just about all of the better controllers have bleed-off resistors onboard, don't count on it. that nice little puppy in sheep's clothing will bite you hard! the controller's smoothing capacitors store a charge capable of biting off the end of a screwdriver.

btw, hope to see you in february! give me a call sometime if you wish.

hi fredr!

moose

Yes, you've hit the nail on the head! That's how my electronically-challenged mind works.

Rather than running the power cables back to the control panel, I would rather insert a single-pole contactor (normally off) into the power circuit, so I can kill power to the loco remotely. But then, I'm biased because my current setup is to run the loco from the rear of the train*, and I don't want to run power cables all the way back there. Shortly, I plan to add a couple more cars to the train.

*Sort of a conductor's-eye view. Not that the sugar plantation had cabooses or conductors....

_________________
Dan Watson
Building IC mikado in 1.5" scale

G,day....the runaway thing is what had me worried, that is why there is a micro switch wired to the bottom of the brake lever on my riding car. Slight pressure forward on the lever and all is honky dory, let go of the lever or apply brakes and all power is cut from controllers and motors.For slow work around the yards this switch is bypassed, but the bypass switch is also a quick hit kill switch.
Out on the track if I touch the brakes and release them the controllers have a soft start so you don;t get a sudden jerk on repower.
Both motors are separately wired so it would be the same as multi units. At the present time I am building a railmotor and eventually plan to run it in tandem with my critter. I have obtained a bigger control unit for this and if it is up to scratch another will replace the 2 in the critter. Though at the speed I work this could be a couple of years off

_________________
Have a good one....John.

hi all,

thanks for some great discussions, but there was a set of questions asked by derek that we missed. i've quoted his original question to see if we could answer them.

multi-notch (progressive relay) type of controller? there are several ways to think about this, is derek asking about a set of input relays or output contactors?

if on the input side of things, will the notch settings be additive? in other words, each notch adds a new relay signal path or will progressive notches just move the signal path to a new relay and leave prior relays in a de-energized mode? how do i mean? in the case of older golf carts in the days prior to pwm controllers, a notched footpedal caused sets of solenoids to be energized which placed a resistor coil between the batteries and the motor. the system worked in descending mode. it placed all resistor coils inline and the reduced the number of coils as the controller pedal was pressed. when going flat out, it was a straight signal path from the batteries to the motor. using this type of controller (while it can still be found) isn't recommended because it wastes energy and has been known to causes fires. when in operation, the coils can get red-hot. if derek were to choose the progressive contactor setup, it would mean (if he were using 36 vdc for instance) using the contactors to add individual batteries in series to control speed. none of the above systems are palatable!


6491: nice to have you with us. most people see controllers and control systems as monolithic...they are not. they are made up of many subsystems and external circuits. your kill circuit shows thought put towards the unthinkable. i put it to you and the others, in the same terms as the steam guys...if you've got a hot fire, low water, and building steam pressure...how many ways would you like to be able put in more water? if those fail, what's your drop-to-dead answer for creating a safe condition?

i'm not chicken little and no, the sky isn't falling...just trying to get you to think about how and what systems you are designing and building.

moose

You might find someone with a West Valley Live Steamers Box Cab unit. There were lots of them made and they are all MU capable. I've seen pictures of more then 10 of them ganged together and being controlled by one person. Now that's some pretty amazing power there.

--M

_________________
Allen Models Chloe, MEG Steam "Wendy", 3/4" scale "Anny"
Darjeeling B-Class project - sonadaworks.com
Photography and more - www.mikemassee.com