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  • Author Author: vsluiter
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A little bit of progress

vsluiter

Need for speed

OK. All contestants received an email last week about having to finish their project by the 30th of November. That's getting very near! I had sent my board file to OSH park, and everything went nice and fine until I got the expected delivery time... 1st of december. Ouch. I've sent my files to another board house as well, as I hope to get some complete hardware going by the end of the month. I've got the option to have OSH park shipping faster, but that would cost me quite a bit more.

 

In the meanwhile...

While I'm waiting for the boards I can do some other work: prototyping the power converter and completing the design. I've updated all parts in the schematic (attached) so that all parts have the correct Farnell order codes. Also, to remember the target for my project, I'm working on both the LEGO train charger and the 'general' toy charger. The train charger will be a coil in a modified LEGO train track (see my previous post), whereas I've go a hilarious thought about making a charger for other children's toys. I'm not going to give disclosure yet image

 

Testing the track

As mentioned above, I modified a piece of LEGO track to get the charging coil closer to the receiver. This works like a treat! I've done some testing, as can be seen in the video below:

Of course, this is using Qi in a way not intended; moving over a target, and then trying to locate the charger. When I started this design I had in mind that I would be able to let the train run to the station and recharge when the battery is nearly empty. This is still possible, but using the detection mechanism of the Qi receiver is only possible when moving very slowly. I guess I need another mechanism aswell to let the train know when it is close to the receiver. Maybe I'll try something with a Hall detector to detect the magnet of the transmitting coil.

 

What I found remarkable was that once the connection is established the reach of the system is quite large; of course this can be explained by the communication that has to be started, etc, etc but still... Great stuff!

Attachments:
QiReceiverChargerv2.sch.zip
  • in reply to DAB

    Hey DAB,

    I really like the simpleness of your idea! Very simple and robust.

    My thought was to use my own open source lego receiver (www.hackvandedam.nl/openpowerfunctions) and add sensing for a low voltage and sensing for either a magnet or try to use the signal from the receiver. That way I can neglect the remote control when the input voltage is too low and run the train at slow speed to the transmitter. Still, your suggestion has set a firm foot in my thinking process. Thanks!

  • From the video, it looks like you have a small sweet spot to hit.

    You might want to set up an IR LED/sensor and use a strip of paper with different shading.  Once you hit the paper strip, you cut the speed proportional to the darkness of the strip so that the train is moving very slowly as it moves into the charging area.

     

    Should be easy enough to setup and implement.

     

    Just a thought,

    DAB