How I built my own DC handheld controller

Well spotted Sol. :thumbs

I like it Frank - I like it a lot. :doublethumb

Frank, the circuit that our local group used had a 2N3055 as the power transistor with it mounted externally on a substantial heat sink as at that time, locos used were Athearn older motors which took at least 500 + mA & most of time, double headers.

Have you tried your unit on older style motors that required a large substation outside your house to power them - you know the motors - old Hornby & Triang?
Modern motors  run on the sniff of an oily electron

[user=95]Sol[/user] wrote:

…………………………………………
Modern motors  run on the sniff of an oily electron

What does an oily electron smell like Sol ?  I know what the older gas guzzlers smell like - flames !!!

Sol,
I think I know the type of controller you are talking about.
most of these controllers use the 2N3055 as a voltage (emitter) follower with no EMF feedback this of course will make slow starts and slow running very difficult.
The circuit I am using makes use of the motors back EMF in a comparator to give constant speed over all load conditions (within reason of course).
I intend to do a few trials with this controller under different conditions before I even think about offering any for sale.
As for older motors then that should not be a problem. Even my old Hornby pannier (X04 motor) runs as sweet as a nut, with a silence that is almost scary. Even the lateral movement of the armature shaft is overcome. The performance is amazing.

The only fly in the ointment I can see at the moment is the one of keeping the output darlington cool. There is not much room for a decent heat sink in the case I have used. No such problem with panel mounting of course where there is room for a decent heatsink.

I may have to make the hand held case a little bigger to accommodate  a larger heat sink and some extra circuitry for overload/short circuit protection.

As I said earlier I have no claim to the circuit design, that should be credited to Roger Amos author of "Model railway electronics"

Anyway trials and development testing continue.

I'll post test results here as and when.

Cheers
Frank

Interesting comment re the performance with the X04 motors Frank.

i recently purchased a BEC tram motor which appears to be very similar to the X04 - 3 pole and ran like a drunk but would only set off on full throttle.  I had to abandon the project as I could no longer afford the claims for whiplash from the passengers !!

Ian (Morton) fitted a decoder to it giving a huge improvement but it's still dinosaur engineering.  I wonder how they would perform with your controller ………………..:roll:

Frank, I will admit, your controller looks far better than mine as it does not have the large external heatsink.

Hi all,

Not trying to recycle this thread but did anybody take a copy of the circuit being talked about in this thread? Seems like Frank took his bat and ball with him! Always on the lookout for anything different!

If you could upload the diagram for all our benefits, … thanks

Regards

Trevor

Hi Trevor,

"Model Railway Electronics" by Roger Amos (Patric Stephens Limited, ISBN 1 85260 591 X) has 2 sections on controllers with diagrams/Maplin parts and numbers. Simple closed loop to PWM, the latter of which appears very similar to the one discussed. The circuit for this was originally described in Model Railway Electronics and Electronics Today (no dates given, but they will be pre-1998 and probably pre-1990). It states in the book "The pulse width is controlled by a servo which compares the speed control setting with the motor back EMF".

Amazon UK has the book for £5.00 (my copy was a birthday present, list then was £19.99). Pre-DCC of course which is why it is so cheap. First published in 1990, but still useful for the DC folks. Lots of interesting add-on projects (on-board DC sound and rechargeable battery-powered carriage lights for example).

Nigel

Hi Nigel, 

Is it this one?  http://www.rogeramos.co.uk/pwam.htm

Thanks and Cheers

Trevor

It could also go even further back with this,
https://www.amazon.co.uk/Practical-Electronic-Model-Railway-Projects/dp/0859343847/ref=sr_1_4?ie=UTF8&qid=1473062162&sr=8-4&keywords=bernard+babani+railway
or this
http://www.abebooks.co.uk/servlet/BookDetailsPL?bi=20121235148&searchurl=kn%3Drailway%26sortby%3D17%26an%3Dpenfold
I seem to remember R.A. Penfold model railway books from Bernard Bambini, had hand controller circuits in them back in the late 70s (and probably before).
I know I've got them stuffed somewhere in the back of the library (spare bedroom) but haven't seen them in at least 30 years….

[user=374]xdford[/user] wrote:

Hi Nigel, 

Is it this one?  http://www.rogeramos.co.uk/pwam.htm

Thanks and Cheers

Trevor

Hi Trevor,

Yes, that's the one.

Nigel