Oxford Rail Janus - Battery Power/Radio Control Conversion

[Corbs]

This has been on my 'to do' list for AGES as it's for a friend of mine and as per tradition I took months to get around to doing a job that need only take hours.

 

 

Standard Oxford Rail Janus - nice motor, probably won't use much power.

90mah LiPo battery

Deltang Rx41 receiver from Micron Radio Control
'UM' leads 

The small battery is due to not being able to find one that is exactly the right shape for the loco - this is a recurring challenge, almost every time I do this, the battery will be about 2mm too big in one dimension. It might get swapped for a different battery in the future.

 

There's not a great deal of space under the hoods, and the narrow width of the upper bodywork presented an interesting challenge.

I popped the hood covers out from underneath (scraped away the thin bit of glue) and drilled some holes with the pin vice drill, then opened them up with the file to make a nice 'ole.

 

Into this the charging port shall go. In the battery setups I use, annoyingly the port is a male rather than a female port, so stands proud. The solution here was to rummage through the spares box for... another box.

 

 

This was a OO scale bin of some sort, cut down to size and filed flat (ish).

Drilled a hole through it and passed the charging port through.

 

Some CA glue and activator was used to fix it in place, then I smeared a load of 5 minute Araldite around it to seal the thing together.

Note I cut down the tabs on the side of the charging port before doing all of this as it means much less force is required to pull wires apart.
 

 

 

The whole box was bonded in with Araldite to make it nice and secure.

 

Next component in the charging circuit is this SPDT (I think) switch.

 

 

Battery BLACK goes into the central pin.

Charging port BLACK goes into the one closest to the running board.

Receiver BLACK goes into the other pin.

 

This means the loco is either in CHARGING mode (battery goes to charger) or RUNNING mode (battery goes to receiver).

It cannot be run while it is charging and vice versa.

This switch was glued to a piece of plastic which was then bonded to the running board. For this to fit, I cut off the metal tab on the chassis block (there is no retaining screw on this corner any more)

 

 

Receiver goes under the hood at one end, secured only with black-tack. Aerial is folded over and black-tacked too.

Yellow wires go to the motor - I removed the pick up wires and pick up plates.

 

 

 

Battery is under the hood at the other end - see what I mean about the odd shaped area. Maybe a cylindrical battery would be better in this space.

 

 

 

Give it a test, yay it works.

 

 

Charging test.... very much not a success.

 

Something was clearly wrong as soon as I plugged it in. 

Every first battery/charging test I do, I do on the hob in the kitchen as it's a heat resistant surface with very few flammable things in the immediate vicinity.

I usually charge off a USB connection on a power brick rather than the mains.

The second the charger was plugged, in, it started to heat up to the extent that it burnt my finger within 10 seconds. Surprisingly it wasn't even plugged into the power brick! Something obviously amiss there.

 

After dismantling nearly the entire electrical circuit and trying to fault-find with the multimeter and finding no short circuits at all, a friend suggested something.

 

Can you see it?

 

 

 

That's right, some absolute clam has wired up this UM lead (the one I am using as the built-in charging port) back to front compared to literally every other one I have, and some other clam (me) didn't think to check it.

 

Cut the charger cables back underneath, and wired on correct colour cables, reconnected everything else.

 

Success! It now charges properly and a potentially flammable disaster has been avoided.

Always check your circuits!

 

A few more tests before decals were applied and handrails/details re-attached.

 

 

As the switch would hit the sandbox, I cut this one in half and re-attached - you can see the switch here. I switch it on and off with tweezers.

 

 

All done! 

Here is the wiring diagram.

 

Hope this is useful.

 

Edited July 13, 2022 by Corbs

[wasdavetheroad]

Excellent inspiring post. Just shows what can be done but unfortunately my precision fitting days are over due to increasingly ancient hands so all my locos need battery removal for charging.

 

Do you have a continuous circuit of any size? I test my battery capacity by fully charging it and timing how long it pulls a typical load before the LVC cuts the power to save the battery. The Rx-41 still has LVC?

[Giles]

Very nice! It makes me feel positively luxurious getting 1000mAh batteries in some of the narrow gauge stuff!

[Corbs]

11 minutes ago, wasdavetheroad said:

Excellent inspiring post. Just shows what can be done but unfortunately my precision fitting days are over due to increasingly ancient hands so all my locos need battery removal for charging.

 

Do you have a continuous circuit of any size? I test my battery capacity by fully charging it and timing how long it pulls a typical load before the LVC cuts the power to save the battery. The Rx-41 still has LVC?

 

Thanks  I think the Rx41 does cut out at low voltage as I've never run a battery all the way down with one, it always still has power for the LED on the Rx to tell you it's low.

I usually run them on a rolling road at full power and time them so will see how this one gets on.

 

3 minutes ago, Giles said:

Very nice! It makes me feel positively luxurious getting 1000mAh batteries in some of the narrow gauge stuff!

 

Indeed! It's generally easier using kit bodies as you get to decide the space inside - unsurprisingly RTR chassis are rarely designed with gaping holes inside where there could be a chassis casting.

[Corbs]

Have added a wiring diagram.

[Tickplan]

Fascinating and thank you for posting this and other posts, with videos: they help so much to demystify the world of model railway radio control. 

However, there is one point I am not clear about and would appreciate your comment. I am not familiar with the model but assume it is made to run out of the box on a conventional analogue layout using 12 volts DC.  I would therefore expect to find some sort of "voltage booster module" in your circuit (to boost the 3.7 volts to 12 volts) but there isn't one. The motor hasn't been swapped out for a lower voltage one than I can see nor does it appear to run very slowly - so how is this working? (and working so well?)

I am intrigued.

 

Bryan

[Corbs]

12 minutes ago, Tickplan said:

Fascinating and thank you for posting this and other posts, with videos: they help so much to demystify the world of model railway radio control. 

However, there is one point I am not clear about and would appreciate your comment. I am not familiar with the model but assume it is made to run out of the box on a conventional analogue layout using 12 volts DC.  I would therefore expect to find some sort of "voltage booster module" in your circuit (to boost the 3.7 volts to 12 volts) but there isn't one. The motor hasn't been swapped out for a lower voltage one than I can see nor does it appear to run very slowly - so how is this working? (and working so well?)

I am intrigued.

 

Bryan

 

Hi Bryan, you are correct I've not put a voltage step-up in this. It is a 3.7v battery powering a 12v motor. That means that if running flat out, the loco is doing about a quarter of what full throttle would be if it was still 12v.

 

I could have fitted an upconverter but it would have meant shortening the battery run time, and as the battery is a teeny 90mah one anyway, it wouldn't be much fun to play with. Handily the model runs far faster than the prototype did, so it can now crawl about at realistic sub-10mph speeds.

 

The small modern motors don't use as much power as older ones so the batteries tend to last a bit longer (which is nice).

 

I guess it might mean that the model isn't as powerful as it was, as you can't give it the beans, but it's only going to live on a small shunting puzzle anyway.

[PenrithBeacon]

Thanks for that.

I have one of these which I intend to convert to P4 using the Judith Edge chassis kit. Interesting that the RC gubbins will fit in the original chassis.

Terrific stuff! 

[Corbs]

59 minutes ago, PenrithBeacon said:

Thanks for that.

I have one of these which I intend to convert to P4 using the Judith Edge chassis kit. Interesting that the RC gubbins will fit in the original chassis.

Terrific stuff! 

I think if using the JE chassis you might be able to free up a fair bit of room for battery space?

[PenrithBeacon]

Hoping for that!

[CME and Bottlewasher]

On 07/11/2021 at 22:39, Corbs said:

This has been on my 'to do' list for AGES as it's for a friend of mine and as per tradition I took months to get around to doing a job that need only take hours.

 

 

Standard Oxford Rail Janus - nice motor, probably won't use much power.

90mah LiPo battery

Deltang Rx41 receiver from Micron Radio Control
'UM' leads 

The small battery is due to not being able to find one that is exactly the right shape for the loco - this is a recurring challenge, almost every time I do this, the battery will be about 2mm too big in one dimension. It might get swapped for a different battery in the future.

 

There's not a great deal of space under the hoods, and the narrow width of the upper bodywork presented an interesting challenge.

I popped the hood covers out from underneath (scraped away the thin bit of glue) and drilled some holes with the pin vice drill, then opened them up with the file to make a nice 'ole.

 

Into this the charging port shall go. In the battery setups I use, annoyingly the port is a male rather than a female port, so stands proud. The solution here was to rummage through the spares box for... another box.

This was a OO scale bin of some sort, cut down to size and filed flat (ish).

Drilled a hole through it and passed the charging port through.

Some CA glue and activator was used to fix it in place, then I smeared a load of 5 minute Araldite around it to seal the thing together.

Note I cut down the tabs on the side of the charging port before doing all of this as it means much less force is required to pull wires apart.

 

 

The whole box was bonded in with Araldite to make it nice and secure.

 

Next component in the charging circuit is this SPDT (I think) switch.

 

Battery BLACK goes into the central pin.

Charging port BLACK goes into the one closest to the running board.

Receiver BLACK goes into the other pin.

 

This means the loco is either in CHARGING mode (battery goes to charger) or RUNNING mode (battery goes to receiver).

It cannot be run while it is charging and vice versa.

This switch was glued to a piece of plastic which was then bonded to the running board. For this to fit, I cut off the metal tab on the chassis block (there is no retaining screw on this corner any more)

 

 

Receiver goes under the hood at one end, secured only with black-tack. Aerial is folded over and black-tacked too.

Yellow wires go to the motor - I removed the pick up wires and pick up plates.

 

 

 

Battery is under the hood at the other end - see what I mean about the odd shaped area. Maybe a cylindrical battery would be better in this space.

 

 

 

Give it a test, yay it works.

 

 

Charging test.... very much not a success.

 

Something was clearly wrong as soon as I plugged it in. 

Every first battery/charging test I do, I do on the hob in the kitchen as it's a heat resistant surface with very few flammable things in the immediate vicinity.

I usually charge off a USB connection on a power brick rather than the mains.

The second the charger was plugged, in, it started to heat up to the extent that it burnt my finger within 10 seconds. Surprisingly it wasn't even plugged into the power brick! Something obviously amiss there.

 

After dismantling nearly the entire electrical circuit and trying to fault-find with the multimeter and finding no short circuits at all, a friend suggested something.

 

Can you see it?

 

 

That's right, some absolute clam has wired up this UM lead (the one I am using as the built-in charging port) back to front compared to literally every other one I have, and some other clam (me) didn't think to check it.

 

Cut the charger cables back underneath, and wired on correct colour cables, reconnected everything else.

 

Success! It now charges properly and a potentially flammable disaster has been avoided.

Always check your circuits!

 

A few more tests before decals were applied and handrails/details re-attached.

 

 

As the switch would hit the sandbox, I cut this one in half and re-attached - you can see the switch here. I switch it on and off with tweezers.

 

 

All done! 

Here is the wiring diagram.



 

Hope this is useful.

 

Very nice work, most helpful, I always seem to get defeated by scale, space available, motor/gearbox efficiency, battery size and tech. I plough on regardless.

[Corbs]

A bit of Maskol, then a coat of Tamiya Matt lacquer, once that was mostly dry I dry brushed on some weathering powder to give the impression that it's still fairly new but has been subject to work around the yard. Sealed with a dusting of lacquer.

 

 

 

 

 

Edited July 13, 2022 by Corbs

[Corbs]

Pictures fixed/reuploaded