Powering PF motors from wall socket (USA)

[jimmythefly]

I've got a great ball contraption module that I've built using a power functions M motor. Right now it's powered from the battery box, but ideally I would find a way to power it from the wall socket. Is there a part or transformer that is meant to do this? Is there a mod or off-the-shelf part I could get from an electronics store that would work?

I know how to solder and have mechanical skills, just want to make sure I don't fry my motor. This would be for USA wall current, 120V AC

Thanks.

Jimmy

[trekman]

I've got a great ball contraption module that I've built using a power functions M motor. Right now it's powered from the battery box, but ideally I would find a way to power it from the wall socket. Is there a part or transformer that is meant to do this? Is there a mod or off-the-shelf part I could get from an electronics store that would work?

I know how to solder and have mechanical skills, just want to make sure I don't fry my motor. This would be for USA wall current, 120V AC

Thanks.

Jimmy

We have been using a variable transformer (from electrical hobby shop) which has been set to 9v on our power functions stuff. Bear in mind that we have been using 220V in Ireland. It appears that power has to go to the PF battery box socket (beside the switch). We were able to use a hacked older style 9v lead and an PF adapter lead to get the power to the battery box. You can just stack the other plugs and receivers on top of this first plug. I found that powering motors from the transformer, and ommiting the battery box, did not work. I hope that this helps.

[DLuders]

You need to get a 2868b "Electric, Train Speed Regulator 9V" unit, powered by a 70931 "Electric, Train Speed Regulator 9V Power Adaptor 120V 60Hz."

On the electrified 2 x 2 plate at the "north end" of the Train Speed Regulator, connect a 60656 "Electric, Power Functions Extension Wire with one Light Bluish Gray End (length 20cm)." The Light Bluish Gray end of the wire connects onto the Train Speed Regulator, and the Dark Bluish Gray end connects to the (Dark Bluish Gray) Power Functions Motor wire.

I just confirmed the arrangement described above with the parts I have, and it works great in the USA.

[hoeij]

I've got a great ball contraption module that I've built using a power functions M motor. Right now it's powered from the battery box, but ideally I would find a way to power it from the wall socket. Is there a part or transformer that is meant to do this? Is there a mod or off-the-shelf part I could get from an electronics store that would work?

I know how to solder and have mechanical skills, just want to make sure I don't fry my motor. This would be for USA wall current, 120V AC

Thanks.

Jimmy

You can find adapters for all sorts of voltages. Chances are very good that somewhere in your house (probably already plugged into one of your outlets) you have an adapter that produces 6V, or 7.5V, or 9V, or etc.

Any adapter that says: DC, with a voltage of 9V or lower, would be OK.

Most adapters are DC, but check nevertheless (don't use AC).

I also have a variable adapter (I don't remember where I bought it from, but it was less than $10) and it has two buttons, one to reverse polarity, and the other to choose from 1.5, 3, 4.5, 6, 7.5, 9 and 12V. Perfect for the M motor, it'll even allow you to change the speed.

[fred67]

If you set it up right, you don't need a regulator like the 9V train regulator... you can use the remote and receiver to get all the benefits of PF (including variable speeds) without the drawback of batteries. You may need to modify the extension cable, but it's not a severe alteration.

[rgbrown]

I've got a great ball contraption module that I've built using a power functions M motor. Right now it's powered from the battery box, but ideally I would find a way to power it from the wall socket. Is there a part or transformer that is meant to do this? Is there a mod or off-the-shelf part I could get from an electronics store that would work?

I know how to solder and have mechanical skills, just want to make sure I don't fry my motor. This would be for USA wall current, 120V AC

Thanks.

Jimmy

To add to what others have said, the "safe" solution would be as follows:

• Get a transformer that supplies 9V or less (not more)
  
• Make sure it's rated for at least 1A at 9V. If you try and draw too much current you run the risk of damaging the transformer and at worst creating a fire risk.
  
• Wire it to the internals of the battery box, not the top. This shouldn't be too hard, and that way you get the benefit of the overcurrent protection provided by the battery box. The battery box trips at about 1.3A I think (there's a thread somewhere on here where it's been tested). The train regulator will have its own overcurrent protection.
  

That said, if it's just a single M-motor that's not working very hard you won't be drawing anywhere near 1A, and you wouldn't need to run through the battery box like that and you could use a much lower current transformer. However if you're going to increase the power functions component of your build significantly then you'll need to be a bit more aware of the potential issues.

Edited April 14, 2011 by rgbrown

[Splat]

This is an expensive option, but does work:

Get a Power Functions Rechargeable Battery Box, which has a socket for a Power Functions Transformer 10VDC, which plugs into the wall socket.

The rechargeable battery box can be turned on while the transformer is plugged in.

I'm not sure if the battery box will have any problems if it is plugged in for a prolonged length of time though.

[Mortymore]

I would say that by plugging the battery charger to the battery you will only be charging the battery, and battery at the same time will provide the energy for the motor. You will not be providing direct current to the motor, through the charger.

Be careful to provide current to a PF motor, through cheap wall adapters since they have awful DC current rectification (ugly ripple), and usually the maximum current that can be drawn is 300mA...500mA and a stalled PF XL motor can draw 3 or 4 times that.

Cumps

PS: 100 posts... I'm a Citizen now

Edited April 14, 2011 by Mortymore

[jimmythefly]

Thanks everyone! Exactly what I was looking for. I never owned any Lego motors (well, I had Wind-up motor) but that hardly counts) until the PF stuff came out. A local LUG member mentioned the train regulator and wall-wart for it, I bricklinked them last night but neglected to get the PF wire 60656. Back to bricklink!