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Home brew handheld controller (DC)

Dukedog

Entry posted by Dukedog

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Preamble

Since I rewired my layout I have provided for two controllers to be used.

Once the extension is built the fiddle yard will be up to 8ft away from the main operating position. To make operations easier I have introduced "cab control" where a train leaving the fiddle yard is under the control of the "main" operators controller.

A train travelling to the fiddle yard will be under the control of the fiddle yard operators hand held controller.

switching from one controller to the other is done manually by a switch on the main panel.

This of course requires two controllers. As I only have one (a Gaugemaster hand held) I decided to build another.

This brings me on to the main topic of this bog entry.

Circuit diagram

 

The circuit of my home brew controller is shown below.

blogentry-6768-0-34076800-1312481172_thumb.jpg

It's a very simple design using only a few components but, the control of locos from this controller is stunning.

Because it is a closed loop controller using the back EMF of the motor as feedback the slow start and smooth running beats a lot of ready to use designs.

Note that there is NO smoothing capacitor, this is because the voltage needs to fall though the 0v point for the back EMF voltage to be measured. If a smoothing capacitor was fitted the controller would still work but, slow starts and smooth slow running would be impossible.

 

I take no credit for this circuit as it is quite a common type of control for small DC motors.

Constucrion

 

 

The controller (less transformer of course) is built into a small plastic box.

The method of construction though needs some explanation.

 

Instead of using a printed circuit or strip board I have used my "Ugly bug" technique using "islands" of PCB material with the components surface mounted on them.

the picture below shows what I mean.

blogentry-6768-0-00881300-1312481261_thumb.jpg

I did however use a small piece of strip board for the rectifier diodes (seen on right hand side of box).

 

I find this method of construction very simple to do when just a few components are involved and this method lends itself to prototype development, allowing quick component changes when developing new ideas.

 

Here's a close up of the main assembly

blogentry-6768-0-55254600-1312481323_thumb.jpg

And finally a picture of the finished and tested controller along side my Gaugemaster unit.

blogentry-6768-0-80762700-1312481392_thumb.jpg

If anyone is interested in building one and needs more info ,I'll be happy to help.

 

Cheers for now

Frank

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18 Comments

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  • RMweb Gold
Brinkly
  • RMweb Gold

Great work Frank, just out of interest how much have you saved building one?

 

Kind regards,

 

Nick

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Liddy

I like the simplicity of that circuit, I'll build one at the weekend, all I need to find is a BC107, there must be one around here somewhere.

Nice work

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Dukedog

Great work Frank, just out of interest how much have you saved building one?

 

Kind regards,

 

Nick

 

Hi Nick,

Thanks for the comment,

I reckon I have saved over 60% of the cost of the Gaugemaster job.

Nothing wrong with the Gaugemaster though apart from the price!

 

the only negative thing I find with the Gaugemaster controller is that most of the useful control is cramped at the bottom end of the control knob.

If you advance the controller to half travel it takes off like a rocket!

I'm thinking of adding a small modification to it but don't tell Gaugemaster tongue.gif

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  • RMweb Gold
Brinkly
  • RMweb Gold

I'm most impressed Frank! Good old British engineering!

 

Regards,

 

Nick

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modfather

Intresting... please keep us posted on the gaugemaster mod - I'm interested to see what you do before I start playing with a pc interface controller... ( it's a hnc project, honest...)

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grandad bob

Hi,

I have just found your controller circuit and fancy having a go at building it.

I have all the components but being at the bottom end of electronic skills I would appreciate some advice please.

Can you please help with the B,C and E positions on each transistor in relation to your circuit diagram, especially the TIP147?

Many thanks,

Bob

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Dukedog

Hi,

I have just found your controller circuit and fancy having a go at building it.

I have all the components but being at the bottom end of electronic skills I would appreciate some advice please.

Can you please help with the B,C and E positions on each transistor in relation to your circuit diagram, especially the TIP147?

Many thanks,

Bob

 

Bob,

I have sent you a PM with connection details

Cheers!

Frank

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kandc_au

Hi Frank,

Could I also impose on the info for the way around the bits are connected.

All being well I shall be picking up the parts this week.

 

Khris

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Dukedog

Hi Frank,

Could I also impose on the info for the way around the bits are connected.

All being well I shall be picking up the parts this week.

 

Khris

 

Details sent via PM

Cheers!

Frank

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Jannie

Hi Frank,

 

Could you please help me as well regarding the transistor connections. I've tried connecting them as per the schematic but had no luck so far.

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Chuntybunt

I like the simplicity of this controler and would like to give it a go. I just have one question, your final picture shows the finished controler with an led that is not in the circuit diagram, what is it's purpose and how does it fit into the circuit. OK two questions.

 

Cheers

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Dukedog

Sorry about the delay in posting answers to peoples comments and questions but, here is some further information that may be useful.

 

Transistor Pin outs, I get lots of PMs and Email asking about the device connections so I'll post some info here.

 

msg-6768-0-39004300-1355316938.gif

 

 

For the TIP147 Transistor use the pin out for the TOP-3 case

 

For the Bc107/8 transistor use the TO-18 case.

 

The LED that is not shown on the circuit diagram is simply wired in series with a 1K0 resistor across the controller output but BEFORE the reversing switch.

This simply gives an indication of power output. nothing more. I added that after I published the circuit above.

 

Hope this information helps,

Frank

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hartleymartin

Is there a drawing which shows how to make this circuit on a piece of copper strip-board (veroboard)? I'm interested in making one of these.

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jwd

Superbly simple.

 

One question :

 

How would you adjust the sensitivity and/or switch the feedback element on/off if required in your circuit?

 

thanks

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HantuBlauLOL

Hi

 

Your controller is amazing! I've just built one and the slow speed performance is great.

 

However I got a problem, the train can't go reverse even after I switched the DPDT switch's polarity.

 

Any suggestions?

 

Thanks!

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BruceV

Hi Frank,

 

Is the short circuit or overload protection built into the power supply you are using?   If not how does the short circuit/overload protection work in this circuit?

 

Am I correct in assuming that the 22K pot is lin and not log?

 

Is this controller ok with DCC fitted loco's?

 

What is the approximate output current?

 

Thanks

 

Bruce

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  • RMweb Gold
ikcdab
  • RMweb Gold
On 30/06/2015 at 23:04, BruceV said:

Hi Frank,

 

Is the short circuit or overload protection built into the power supply you are using?   If not how does the short circuit/overload protection work in this circuit?

 

Am I correct in assuming that the 22K pot is lin and not log?

 

Is this controller ok with DCC fitted loco's?

 

What is the approximate output current?

 

Thanks

 

Bruce

I've come across this topic just now.  Also,  I would be interested in how you deal with the short circuit/overload protection.

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