Homemade Gaugemaster U Controller

[bertiedog]

Back to the UF, the parts all came in the post, amazingly some as fast as a couple of days from Hong Kong......so assembling the two boards tomorrow to test them out, these are full 12 volt as usual. No cases as yet though, so bare bones tests.

[AndyID]

According to some net postings on the lm317, if you put diodes in series it does drop the voltage, but not to the expected value as it introduces instability, dependant on the load current. Maybe it alters a graph of the exact output as the load alters. It barely matters for model moor controllers, one I did for a friend used the higher power version of the 317, and exhibited the same 1.25 bottom limit, cured by two diodes. It needed them as he wanted a digital voltage display on the output, which of course now showed it had a max voltage of 12v minus the 1.24Volts.

Stephen

 

Yes, diodes are a bit "resistive", so the actual voltage drop will, to some extent, depend on the current drawn by the motor. Your "stepped rheostat" will have a similar problem and you might see some jack-rabbit starts. It might be best to do a bit of experimenting to find out what works best with those motors.

[PatB]

 

Hello all,

 

I'm altering one of my layouts to a light railway rural terminus, the backscene will be nearer the edge than the previous one. I've had to remove the built in GM 'UF' controller and make a little sort of outrigger extension box to the side and will rebuild the controller into it.

 

I decided to use 2mm grey card to fix the bits to, it's 130mm x 65mm.

 

Drew it out roughly on the card coated it with shellac and cut out the holes and attached the bits

 

This is the underside

 

I will put the GPO jack socket for the AC input on small bracket adjacent to the circuit under the board.

I attached it like this to see if it worked OK, it did I'm pleased to say.

The little bit of Veroboard is attached to the card with Blue Tack.

 

Cheers - Jim

 

[edit] Loaded the top pic twice!

 

 

I like this a lot, but one small point;  is it not better practice, with plugs and sockets, to have the socket on the live side, rather than the plug? Not as much of an issue at model railway voltages but there's still the possibility of a short if the plug gets put down on something metal.

[bertiedog]

Yes, diodes are a bit "resistive", so the actual voltage drop will, to some extent, depend on the current drawn by the motor. Your "stepped rheostat" will have a similar problem and you might see some jack-rabbit starts. It might be best to do a bit of experimenting to find out what works best with those motors.

Busch now use a coreless motor, and it's the same as the 3volt types on Ebay that are sold with a gearbox, and come from digital camera focus systems. So I based the test on the same motor as the current drawn is the same as quoted on the net from a German posting on the Busch motor.

The motors are very sensitive indeed, with very low voltage they draw about 15ma average, and to get control the drag of the transmission in the Busch is vital.

The sets come with a controller that has two AA batteries in it, and a reversing switch! Apparently the locos can run for hours on a set, and quite modest capacitors can act as a stay alive unit in the loco.

They will run on any controller, but only at the very bottom of the range of the control knob.

[Renato]

Gentlemen,

while trying to find information in the internet on how to fix my old Gaugemaster P controller  I found this topic and saw that some of you are keen on Gaugemaster and similar controller circuits. So I subscribed and posted a new topic "Repairing a Gaugemaster P - Help needed". Simply a disconnected wire prevents operation of inertia simulator and I don't know where to solder it back ! So I "reverse engineered" the circuit diagram and posted it showing the broken connection. Unfortunately noone replied to my post yet. This to recall your attention hoping somebody may help me. Sorry for leading you out of topic, and thanks for any help

Renato

[JohnnyDMonic]

Hi there,

 

I am the person who drew that Codar schematic. Please have a look here: