Power Functions Wiring

[andrewganschow]

I just bought a mini air pump today and an extension wire with the intention of splicing the pump to the wire. I wanted to know which wires on a PF cable carry current, and which carry signal for RC controls. I know there are two wires to carry current and two to carry signal, I’m just not sure which wires do what. Thank you in advance for the help.

[John Daniels]

I don't know off hand, but it is easy enough to figure out with a voltage meter on ohms setting and any pf motor lead.

[goggel]

http://www.philohome.com/pf/pf.htm => Edited January 30, 2016 by goggel

[andrewganschow]

http://www.philohome.com/pf/pf.htm =>

thank you for this image, i forgot about philohome.

[Brickthus]

What is the power of the pump? It might be too much for the LEGO PF system.

I used to use a small car tyre air compressor, nominally 12V, but it needed 6 Amps to start and 4 Amps steady current when driving a pneumatic model through the football inflation attachment.

I got a 5-Amp mains-to-12V supply for it but even that wasn't enough.

After I broke that one I got a quiet mains compressor that has a 9-litre air receiver.

The air receiver is useful because the compressor has to run only 40% of the time. It has a fridge motor.

It needed a hose and a tyre-inflator tool to interface with the car tyre football attachment but those parts are relatively cheap.

There is a range of quiet compressors alongside the noisy ones.

The alternative pure LEGO solution is to make a module of a few mini compressor cylinders on a crankshaft from a motor and make a few of those.

I've tried up to 16 compressor cylinders from 2 5292 motors; it needed a big power supply!

It is said that, in a workshop, compressed air costs 10x as much as electricity. This is partly because of the inefficiencies of it as a drive method.

It means you might need up to 10x the electrical power to drive a pneumatic model with mechanical power equivalent to a PF electric model.

Mark

[andrewganschow]

The pump only requires .3 amps. So I'm pretty sure it'll run off of the PF BB.

[RohanBeckett]

you get the one that I got? :)

[andrewganschow]

you get the one that I got? :)

I ordered pump model kpm27h, I think yours was kpm27c. Shouldn't be any major difference.