PWM control

sparky230

sparky230

Registered
Country flag
been working on ideas for new controllers, since my art 5400 died in the summer

http://www.ebay.co.uk/itm/3A-12V-24V-36V-Pulse-Width-PWM-DC-Motor-Speed-Regulator-Controller-New-Switch-/301366802217?pt=UK_BOI_Industrial_Automation_Control_ET&hash=item462adc7729

would this work on my Stainz Fleet ok, I dont have any electronics in my Stainz only lights and Smoke stacks
 
Maybe. It doesn't seem to say what frequency the PWM runs at - if it's too low then the loco will growl along the track at low speed. Also although it says it works from 0% upward, it would be sensible to check it does indeed have zero output voltage when "off".

Obviously you'll need a cross-wired DPDT wired after the output of this module, to change direction, and some sort of overload / short-circuit protection.

Not bad for the price, I'm tempted to get one to try for other projects. I see there are other similar modules for lower voltages etc.
 
I popped one similar to that. I'll try to find exactly which it was.
 
it looks like the same seller lists one with a reversing switch already wired in

http://www.ebay.co.uk/itm/High-Power-PWM-Motor-Speed-Controller-Reversible-Control-Switch-DC-12V-40V-NEW-/271652767911?pt=UK_BOI_Industrial_Automation_Control_ET&hash=item3f3fc448a7
 
Yeah, that one looks more useful. Has a fuse fitted too, although why you'd fit a 10A fuse for a unit rated at 5A max I don't know?? Simple to change it of course.
 
would 15khz be a suitable freq for a stainz, otherwise that looks a useful little unit
 
Yes that should be reasonable.

I was about to update my last post to comment about the 15kHz frequency, but the forum went silly and 404'd all over the place for a few minutes!
 
That Pwm unit certainly is cheap.
A more expensive (but interesting) option might be to use a battery power rx unit to control power to the track together with a suitable tx - sort of like the crest revolution base station. A tx which allowed loco selection could then be used for battery powered locos as well as analogue track power. The limitation would be finding an rx that can take the power requirements. The Deltang/RCS rx will do up to 18 volts and 3 amps - enough for a Stainz ( I would expect) but not enough some big locos.
 
I also have the OMEGA-3 ESC that can handle up to 24 volts. It has all sorts of functions built in for battery R/C and although can be used for controlling track voltage, the price structure is pretty high for competing with the speed controller listed above.
 
Chris M said:
That Pwm unit certainly is cheap.
A more expensive (but interesting) option might be to use a battery power rx unit to control power to the track together with a suitable tx - sort of like the crest revolution base station. A tx which allowed loco selection could then be used for battery powered locos as well as analogue track power. The limitation would be finding an rx that can take the power requirements. The Deltang/RCS rx will do up to 18 volts and 3 amps - enough for a Stainz ( I would expect) but not enough some big locos.
Click to expand...

You mean something like this? It's something I built earlier and seems to be exactly what you described

https://www.gscalecentral.net/analogue-(dc)/train-engineer-basic-an-alternative-home-built-version/
 
ntpntpntp said:
Yeah, that one looks more useful. Has a fuse fitted too, although why you'd fit a 10A fuse for a unit rated at 5A max I don't know?? Simple to change it of course.
Click to expand...
It has a maximum 120w output so at 12v it can output 10A ......so a 10A fuse
 
beavercreek said:
It has a maximum 120w output so at 12v it can output 10A ......so a 10A fuse
Click to expand...

Yeah, saw that: but it also says "Maximum continuous output protecting current:5A". Confusing.
 
I'm sure most folks here know this by now (and the original post did specifically mention that none of the Stainzes have fancy electronics), but in case anyone new isn't aware: you should NOT run any DCC-chipped loco on PWM analogue power. If you want to put a chipped loco on an analogue DC track, it must be smooth, linear DC only - PWM will do nasty things to the decoder......

As far as I'm aware, all LGB power packs have always been smooth DC - and systems like the Train Engineer must be switched to the linear DC setting if you've got a chipped loco on the track - this is why you must be wary of the old "basic" Train Engineer, the orange one from the starter sets, because that is PWM only and not switchable like the standard black TE.

Jon.
 
Zerogee said:
- PWM will do nasty things to the decoder......
Click to expand...
Well.... to be honest the most that's likely to happen is the decoder simply cannot work out whether it is seeing DC or DCC and may respond erratically (or at all). The PWM track power for a given scale is well within the electrical specs of DCC for that scale so it's not going to physically damage the decoder. It would be a miracle if somehow the PWM signal happened to look anything like a string of DCC programming bytes and actually managed to change a CV. However the erratic behaviour might include sudden direction reversal or jittering which is obviously not good for gearing etc.

The advice is still sound - avoid PWM with chipped locos, stick to linear pure DC.

I have a small handful of N gauge locos that are chipped, some of them manage to work on my PWM DC controllers but others aren't happy. As a result they don't usually get to run on my layout. I recently acquired a model from ebay with (as an unexpected bonus) £90 worth of ESU Loksound decoder which ran fine on pure DC on my test bench but refused to work at all with the PWM controllers. That decoder has now been replaced with a DC blanking plate as it's a loco I particularly wanted for exhibition use.
 
That's useful to know then, Nick - I was always under the impression that it was a Bad Thing (tm) that should be avoided - maybe the people I originally heard that from were over-cautious....?

Jon.
 
Well, it's certainly not a Good Thing and doesn't do any harm to stick to the rule of avoiding mixing PWM and decoders, to avoid disappointment! As I said, I have some decoders that seem to cope with it, but others certainly don't. It probably depends on the PWM frequency (and maybe other factors) as to whether a decoder can handle that form of power. But from a purely hardware and electrical perspective it doesn't make sense to me that a decoder could actually be damaged or reprogrammed.
 
I have heard that electronics and PWM do not sit well together. I had the chip the controls the flashing ditch lights on my SD70 go up in smoke (quite spectacularly) when running a train engineer on PWM. I usually run non PWM but somehow the switch got moved. Got a new ditch light unit and kept to non PWM ever since and not had another problem. This could of course just be coincidence.

And as I recall LGB stated that using a train engineer invalidates the warranty on their locos - this was after some publicity about problems with LGB decoders and train engineer on PWM.
 
As stated at the begining I dont have decoders in my fleet, I dont need remote control as I have 2 loops, both automatic with colour signals and block working, originally done with lgb pointmotors and aux switches, but replaced by solid state latching relays, although circuit is in essence the same, just no diodes.

The only reason I like PWC or PWM is that my lights and smoke stacks stay fairly constant, thou the speed of the trains can be varied
The layout once running is almost set and forget.
 
I have noticed that on even early (mid 1970's) LGB locos the directional lighting sometimes doesn't work as it should if my Train Engineer is accidentally switched to pulse.
 
The PMC frequency will be the measurement that can screw up the decoder.
According to Greg Elmassian, the frequency of the TE PWC (PWM) output is a pulse repeat duration of 43 microseconds (e.g. 23.2 KHZ rate).
Now if the frequency for the motor which is set in the CVs, is near to this, then I should think, that there could be a lot of problems...(I could be wrong of course).

Greg's explanation with testing is here:
http://www.elmassian.com/trains/dcc-battery-rc-electronics/misc-electronics/aristo-pwc-power

By inadvertently having my track power switched to DC (with PWC ) rather than to DCC supply, when running a DCC loco or two, I have accidentally found that........
....some DCC decoders are not phased at all by PWC, but as has been said already here, there will be those that are and that may give unplanned for reactions.
 
You must log in or register to reply here.
Back
Top