Roger Amos PWAyMan DC controller

[MarkK]

Anybody built one?

[glenn coltas]

hii 

I am just getting the parts list together. then build I hope ! 

will update when done !! ⁹

[spamcan61]

Will be interested to see how you get on, tempted to have a bash myself 

 

Edited October 23, 2019 by spamcan61

[sharris]

Looks interesting - I've thought about combining voltage and PWM, but never got around to implementing it.

 

Something I might do differently is to replace the 555 (these days it would be better to use the CMOS 7555 equivalent) with a 7556 (dual version of the 7555) and use the second timer in astable mode to create the 100Hz timebase, rather than picking it up from the unsmoothed input. That way the controller could be used just as easily  from a switched mode power supply (e.g. a laptop power brick) as from an ordinary transformer and rectifier. For those worried about PWM and coreless motors that might also give the opportunity to raise the pulse frequency.

[Platy787]

If anyone has built this or is intending to (like me) you should be aware that there are differences in the circuits published in ETI February 1986 and Model Railway Electronics 2nd Edition (the book is later published than the magazine article).

 

IC1 7818 / 7815

IC3 2N6050/TIP147

R11 390R/390K

R14 and R13 names are swapped

R13 1k/10k

R14 10k/1k

 

The regulator and darlington are probably due to component availability.

R11 is probably wrong in the ETI article (390R) because the op amp gain in the article is given as 4.9. Was there ever an Errata published?

I'm not sure about the R13, R14 change.

 

I will build to the schematic in the book, but with a BD682 darlington.

[Platy787]

Straight forward build with seemingly too many transistors. I built on Vero board and haven't put it in a case or given it a reversing switch yet. No meter for the speedo, just a no frills build. Tested with a OO Dapol LT 57XX and adjusted to give smooth start and running. The PWM/DC switch gives a slight change, but I only tested it on 2meters of straight track. Similarly with my N gauge test, it can be adjusted for smooth start and running.

 

I have an N gauge terminus with a roundy, roundy extension and shunting performance is most important to me. I already have a number of great controllers that work very well at low speed (including the Roger Amos centre off, Wireless World and Cooler Crawler) so I probably won't put this one in a case.

 

If anyone wants an alternative Pulse and DC combo controller, that also works well, there is a circuit available from the NGF.

Edited April 3, 2022 by Platy787
Renamed to Pulse and DC

[2750Papyrus]

Sounds interesting but plse can the sources (Roger Amos/NGF) be identified?

[Platy787]

Pulse and rising DC Controller from the N Gauge Forum

https://www.ngaugeforum.co.uk/SMFN/index.php?topic=50101.0

 

The Roger Amos centre off is Project 8: Bi-directional Controller from his book Practical Electronics for Railway Modellers.

Edited April 3, 2022 by Platy787
Renamed to Pulse rather than PWM

[Platy787]

I have been checking the output waveforms of my DIY controllers using 3 N Gauge locos, a GraFar 5 pole, a Dapol 45XX and a Kato coreless motor tram.

 

Attached is a pdf of the PWayMan output while driving the 5 pole GraFar loco at start, running and fast.

The Dapol and Kato didn't like the pulses, but the PWayMan has a mode that outputs variable DC.

 

PWayMan Output Waveform.pdf

[Platy787]

Here's an update for anyone still contemplating making one of these controllers. I've been using the Roger Amos PWayMan DC controller for a while now, and I have to revise my comments  about it. I have an N gauge layout where each section is powered through a centre off DPDT switch that allows me to select either of 2 connected controllers. The PWayMan controller has ended up being connected as one of these controllers, with the Cooler Crawler the other. The PWayMan has quite a controllable low speed range, with the ability to set from tickover to a nice crawl speed. Using a 5 pole Poole manufactured Graham Farish loco, it starts with a growl and gently builds speed over about the first 50% of speed pot movement, with it going faster after that. I use an 18V AC plug pack with a 12V/18W lamp in series with the input for overload protection. There is the option of a pure DC output that doesn't use the PWM, via a switch.

 

I've made more than a dozen DIY DC controllers and for me, the PWayMan is one of the best, although some may not like the amount of movement of the speed control required to get it up to speed.