View single post by dan3192
 Posted: Tue May 8th, 2018 06:08 am
PMQuoteReplyFull Topic


Joined: Thu Oct 14th, 2010
Location: Connecticut USA
Posts: 228
Dave, thanks, and yes, that's my plan. My Tx board will power a round 15mm Tx coil attached to the underside of a piece of grooved plastic to simulate a wooden track crossing. The top surface will be positioned at the same height of the track. I'd like it higher, but I use Kadee couplers which have uncoupling pins that come down to about 1/16 inch above the rails. The plastic piece, with coil underneath, will be attached to the Bachmann E-Z Track you see in the photo. The coil wires will connect to the Tx board hidden under the ties. The light from the board will be seen at ballast level via fiber optic tubing from the Tx LED. The Rx coil may be larger and will be mounted under the engine fuel tank and connected to the Rx board either under the frame or above the Li-ion cell inside the engine shell. Likewise, fiber optic tubing brought to the outside will tell me charge coupling is established when Tx and Rx board lights are on together.

Now to your question. Initially, I'll connect the Rx coil and board wiring, via a double throw switch, to a 1S battery management board, with the battery also connected to the board. When the switch is thrown the opposite way, power will flow from the battery and board to a step-up voltage regulator and then to a Del Tang Rx61x Rx/ESC. I say initially because I've been thinking of a way to completely turn off my engine using a toggle or PB and an on board servo, in which case the wiring would be a little different. This would eliminate quiescent battery drain since it is hard wired to the battery management board. 

Re oblong coils, I found some copper beading wire at a local crafts store that might be perfect for forming my own Tx and Rx coils. Thin transformer wire may also work well. This is a tricky subject all by itself, i.e., what gauge wire, how many turns, single layer or double layer, insulating material, bonding material, solid or stranded wire, etc, etc. Suggest you visit the Digi-Key website ( to see if their coils are of interest to you. You should be able to get most of them in the U.K. I don't know if the Tx/Rx imprinted coils referred to earlier can reach stated capacity without almost touching. I think it's a neat idea though. The best I think I'll be able to do is in the area of a 4 or 5mm gap.  I'm trying to stay with the Qi Standard for wireless charging so future parts are compatible. Visit the Wireless Power Consortium website for background information. You will also find useful videos on YouTube. Hope this helps.


Last edited on Tue Jul 31st, 2018 03:50 am by dan3192

Close Window