DIY DC Controller - any ideas

[ikcdab]

Have done a quick totting up and I reckon each controller cost me about £4 for components. Bit difficult to tell exactly as I already had some bits around.  And,  of course, several hours of soldering, unsoldering and resoldering....

[Penlan]

I shall probably be burnt at the stake for this,

but I've used 12v 21w car stop light bulbs to minimise overloads

on my DC controller systems, over the last 50 years. 
So far no fry-ups.

[melmerby]

27 minutes ago, Penlan said:

I shall probably be burnt at the stake for this,

but I've used 12v 21w car stop light bulbs to minimise overloads

on my DC controller systems, over the last 50 years. 
So far no fry-ups.

The PWM controller in the Wireless World did just that, varying the wattage used depending on load required.

Will protect the electronics.

[spamcan61]

40 minutes ago, Penlan said:

I shall probably be burnt at the stake for this,

but I've used 12v 21w car stop light bulbs to minimise overloads

on my DC controller systems, over the last 50 years. 
So far no fry-ups.

Same here !

[mikesndbs]

52 minutes ago, Penlan said:

I shall probably be burnt at the stake for this,

but I've used 12v 21w car stop light bulbs to minimise overloads

on my DC controller systems, over the last 50 years. 
So far no fry-ups.

 

Exactly what my first ever controller had in it a Kerdon Major or was it Cerdon??? Can't even find a photo of one now.

[melmerby]

I seem to remember the all in one Hornby Dublo controller also had an overload lamp.

 

 

 

[Donw]

You could go for a fancy device that was low resistance at a low current but increases rapidly with a high current  and will therefore protect the circuit and send a warning to the user. Oh hang on thats what a car bulb will do.  A 21w one will restrict the current to less than 2A and a 15w one to about 1.25A . There might be a bit of a surge above those values  at the point a short occurs putting the full 12v across the bulb but very quickly reduces as the filament heats up.  The bulb heats up so the transistors don't and the light tells you what is happening. Remove the short and the bulb goes out and cools down circuit restored.

 

Don

[Sol]

and I use the globe as a visual indicator of a short on my DCC layout - in fact one per sub-section.

[melmerby]

1 hour ago, JimRead said:

Hello all,

 

I used Brian Tilbury's pulsed/feedback controller for years.

A few years ago I found Scott's pages: https://www.scottpages.net/ReviewOfControllers.html
He's recently updated the circuit he advocates for shunting being unable to get one D13T1 component in NZ, Cricklewood Electronics sell an equivalent 2N6027.

 

I've authored a how to PDF on how to make it and this assumes that the reader has never made anything electronic before.
It can be seen working here: https://www.youtube.com/watch?v=-TtpHJpefRQ

 

I did make the third one down on Scotts Pages it works in exactly the same manner, using 2 transistors and the SCR. I made it on some Matrix board;

 

Very easy to make like this most bits are connected to each other directly.

It's fine with a short short as well no harm done even to itself.

Cheers - Jim

May I ask why you constructed it like that rather than the usual copper clad stripboard?

[SHMD]

...to be able to "see" or visualize the circuit from above as if looking at / comparing it to a diagram.

 

...i guess. Pretty compact though - and good soldering.

 

 

Kev.

(But yes, a bit unconventional!)

 

[melmerby]

2 hours ago, JimRead said:

Hello Keith, [edit] and Hello Kev

 

Thanks for the interesting question, I made an amplifier using this method, it was easier to copy the photograph I had rather than fiddle with stripboard.

The reasons are it's easier and faster especially if the circuit is a simple one, just follow the circuit diagram.  The holes in the Matrix board have a single copper pad on the other side enabling me to use a U shaped piece of wire to hold down components or to solder in veropins.

Its main advantage over stripboard is being able replace a component, they just slide apart.

Once I started I realised why components have such long leads, I suspect that doing it like this is the preferred method of experimental electronic engineers, its even simpler than breadboards.

 

Cheers - Jim

 

My PDF does have a stripboard layout, I authored it some years ago

OK.

It takes me back to valve days when things I constructed were a bit like that (even commercial products had components strung between tags) but these days I usually use stripboard or sometimes even etch a PCB.

Edited July 21, 2020 by melmerby

[Crosland]

On 18/06/2020 at 23:33, Sol said:

and I use the globe as a visual indicator of a short on my DCC layout - in fact one per sub-section.

 

The apprentice uses bulbs without thinking.
The journeyman avoids them without thinking.
The master uses them thoughtfully.

 

[CourthsVeil]

Back again to the posts above (June 3): I made Frank's (Dukedog) controller some six years ago.

Use it since then with several of my small layouts - still completely satisfied!

As explained in an old post of mine it can be made even without a PCB: just using a choc block connector (five ways) - see here!

 

In addition I use a 12V 10W bulb as overload protection (as Penlan et al. said above).