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 An Experiment in Wireless Charging
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B_A_R
Engine Wiper

Posted - 08/02/2018 :  2:53:33 PM  Show Profile  Reply with Quote
I've been experimenting with Deltang Deadrail. I'm up to three smoked receivers but that hasn't stopped me. This looks interesting.


Country: | Posts: 140 Go to Top of Page

wvg_ca
New Hire

Posted - 08/02/2018 :  4:40:30 PM  Show Profile  Reply with Quote
if the primary and charging coils resonate at about the same frequency, then the charging voltage can be adjusted somewhat by changing the frequency of the primary coil, and using load line analsys to figure out what the resulting voltage on the charging coil would be ...you wouldn't possibly need the step up transformer with it's built in loss amounts, pretty large as the final output current is small ?

regards, Warren

Edited by - wvg_ca on 08/02/2018 4:41:41 PM

Country: Canada | Posts: 20 Go to Top of Page

Bernd
Fireman



Posted - 08/03/2018 :  1:30:41 PM  Show Profile  Visit Bernd's Homepage  Reply with Quote
quote:
Originally posted by B_A_R

I've been experimenting with Deltang Deadrail. I'm up to three smoked receivers but that hasn't stopped me. This looks interesting.



Hi B_A_R, welcome to the thread.

Letting the magic smoke out is not good. Hoping to keep this interesting. Care to go into a bit more detail on your Deltang Deadrail? Pictures? What you've built up and not worked.

Bernd


A PESSIMIST sees a dark tunnel
An OPTIMIST sees light at the end of the tunnel
A REALIST sees a freight train
The LOCOMOTIVE ENGINEER sees three idiots standing on the tracks

Country: USA | Posts: 2606 Go to Top of Page

Bernd
Fireman



Posted - 08/03/2018 :  1:33:15 PM  Show Profile  Visit Bernd's Homepage  Reply with Quote
quote:
Originally posted by wvg_ca

if the primary and charging coils resonate at about the same frequency, then the charging voltage can be adjusted somewhat by changing the frequency of the primary coil, and using load line analsys to figure out what the resulting voltage on the charging coil would be ...you wouldn't possibly need the step up transformer with it's built in loss amounts, pretty large as the final output current is small ?



I think once I have a permanent set up to test I'll start with what the output of the charging coil is and go from there. Still waiting my package for the test to see if it will even work. Hopefully next week some time.

Bernd


A PESSIMIST sees a dark tunnel
An OPTIMIST sees light at the end of the tunnel
A REALIST sees a freight train
The LOCOMOTIVE ENGINEER sees three idiots standing on the tracks

Country: USA | Posts: 2606 Go to Top of Page

wvg_ca
New Hire

Posted - 08/03/2018 :  3:01:35 PM  Show Profile  Reply with Quote
to get alignment is relatively easy, just a bit of hand wiggling fore and aft ...
to get the distance to less than 10mm is quite a bit harder ??


regards, Warren

Country: Canada | Posts: 20 Go to Top of Page

DanT
New Hire

Posted - 08/03/2018 :  9:34:23 PM  Show Profile  Reply with Quote
Hi Bernd,

I went by an earlier thread of yours with the photo of the Rx coil hot glued to the roof of the shell. I don't think this will work, i.e., the coil should be facing the Tx coil, not the magnetic shield. Suggest you try it the way it is first after you're set up, then flip it over 180 degrees and re-glue it if you get no response or magnetic coupling.

Dan



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Norton
Engine Wiper

Posted - 08/04/2018 :  12:48:55 AM  Show Profile  Reply with Quote
Bernd,

The discussions about resonant frequencies got me to thinking about this whole technology. And that brought me to this question.

What sets the resonant frequency? Is it the coils in some way or is it set in the transmitter and the coils built so as to utilize that freq? If a way could be found to change the resonant frequency then the coil size could be changed to accommodate a smaller size. A smaller size would probably be a higher frequency so that could be a good thing for your purposes here. The higher freq might mean higher current required to run the transmitter but first things first I guess. Have you looked into changing the frequency yet? Or can it even be done?

On another thought; do the coils have to be oriented in the same direction to get power transfer or does that orientation just maximize the transfer ratio? Is there power transfer regardless of the directional orientation of the coils? Does it improve when the coils are matching in orientation?

Am I making sense or should I just go to bed?


The V & T lives in my garage. Soon...

Norton

Country: USA | Posts: 175 Go to Top of Page

Bernd
Fireman



Posted - 08/05/2018 :  7:39:31 PM  Show Profile  Visit Bernd's Homepage  Reply with Quote
quote:
Originally posted by wvg_ca

to get alignment is relatively easy, just a bit of hand wiggling fore and aft ...
to get the distance to less than 10mm is quite a bit harder ??



For rough figures just using your fingers to hold the Tx coil isn't bad. Once a suitable set of coils is found, then I'll work on getting the proper distance between coils.

Bernd


A PESSIMIST sees a dark tunnel
An OPTIMIST sees light at the end of the tunnel
A REALIST sees a freight train
The LOCOMOTIVE ENGINEER sees three idiots standing on the tracks

Country: USA | Posts: 2606 Go to Top of Page

Bernd
Fireman



Posted - 08/05/2018 :  7:42:10 PM  Show Profile  Visit Bernd's Homepage  Reply with Quote
quote:
Originally posted by DanT

Hi Bernd,

I went by an earlier thread of yours with the photo of the Rx coil hot glued to the roof of the shell. I don't think this will work, i.e., the coil should be facing the Tx coil, not the magnetic shield. Suggest you try it the way it is first after you're set up, then flip it over 180 degrees and re-glue it if you get no response or magnetic coupling.

Dan



Yes, I did notice I had the Rx coil up-side down. I flipped it over. The results were about the same. That was rather disappointing. I'm waiting for some parts to arrive.

Bernd


A PESSIMIST sees a dark tunnel
An OPTIMIST sees light at the end of the tunnel
A REALIST sees a freight train
The LOCOMOTIVE ENGINEER sees three idiots standing on the tracks

Country: USA | Posts: 2606 Go to Top of Page

Bernd
Fireman



Posted - 08/05/2018 :  7:49:24 PM  Show Profile  Visit Bernd's Homepage  Reply with Quote
quote:
Originally posted by Norton

Bernd,

The discussions about resonant frequencies got me to thinking about this whole technology. And that brought me to this question.

What sets the resonant frequency? Is it the coils in some way or is it set in the transmitter and the coils built so as to utilize that freq? If a way could be found to change the resonant frequency then the coil size could be changed to accommodate a smaller size. A smaller size would probably be a higher frequency so that could be a good thing for your purposes here. The higher freq might mean higher current required to run the transmitter but first things first I guess. Have you looked into changing the frequency yet? Or can it even be done?

On another thought; do the coils have to be oriented in the same direction to get power transfer or does that orientation just maximize the transfer ratio? Is there power transfer regardless of the directional orientation of the coils? Does it improve when the coils are matching in orientation?

Am I making sense or should I just go to bed?



Not being that well versed in this technology, which by the way is the same as a radio station broad casting and your radio being able to tune it's antenna to receive certain stations. I believe this works the same way. You're going to need lots of math to figure out what each part needs to be. Length of the antenna wire has a lot to do with resonating. If you have ever tuned a CB antenna to the CB radio you'll understand how that works.

The coils have to face each other. If you turn one coil 90 degrees the system won't work. Type in "wireless charging circuits" in the search engine and take a look at the circuits.

Bernd


A PESSIMIST sees a dark tunnel
An OPTIMIST sees light at the end of the tunnel
A REALIST sees a freight train
The LOCOMOTIVE ENGINEER sees three idiots standing on the tracks

Country: USA | Posts: 2606 Go to Top of Page

Bernd
Fireman



Posted - 08/12/2018 :  2:57:01 PM  Show Profile  Visit Bernd's Homepage  Reply with Quote
As I said earlier that I went back to look at the CLAG website. They mention a wireless charging tooth brush. Off to E-bay in search of a wireless charging tooth brush. This is what I got for around $24.



It came with instructions on disassembling the brush so when the battery no longer holds a charge you can dispose of the battery properly. Yeah right.




So I took it apart. Hereís what the board looks like, plus the receiver coil. Itís quite small.



A coil comparison from the first Tx and Rx I started with.



A 2.4 volt motor and 2.4 volt NiMH batteries. (Two single 1.2 volt batteries.)



The transmitter board Bottom. This one was a bit hard to disassemble.



The other side and Tx coil. I was surprised to see it had two coils. Havenít figure that one out yet.



The transmitter coil wonít quite fit between the rails.



The receiver coil not fitting between the tracks was the second frustration point. The first was when I did the initial charging. Although the brush battery came pre-charged, the instructions said to charge the battery fully prior to first use. It should charge for at least 20 hours. The led shines red when sitting in the charger. It should turn blue when fully charged. After 30 hours I still had a red light. Question, was it a faulty board? So at this point in my quest for wireless charging Iím going to box everything up and let it simmer on the back burner.

Maybe somebody will read this and start their own research. I hope so.

Bernd


A PESSIMIST sees a dark tunnel
An OPTIMIST sees light at the end of the tunnel
A REALIST sees a freight train
The LOCOMOTIVE ENGINEER sees three idiots standing on the tracks

Country: USA | Posts: 2606 Go to Top of Page

Norton
Engine Wiper

Posted - 08/12/2018 :  6:49:13 PM  Show Profile  Reply with Quote
Bernd,

Did you do the initial charging before you took it apart? Is that when it did not charge?

If so, then I think I can tell why it was for sale...


The V & T lives in my garage. Soon...

Norton

Country: USA | Posts: 175 Go to Top of Page

Bernd
Fireman



Posted - 08/13/2018 :  07:19:05 AM  Show Profile  Visit Bernd's Homepage  Reply with Quote
quote:
Originally posted by Norton

Bernd,

Did you do the initial charging before you took it apart? Is that when it did not charge?

If so, then I think I can tell why it was for sale...



I had it on charge for over 30 hours.

Time for me to let this subject simmer. Perhaps somewhere down the line I'll come across more info and products out there to experiment with. I don't want to get into the electronics hobby again. I pretty sure I could build up Tx and Rx boards from discrete components, but want to get working back on my layout and rolling stock.

Bernd


A PESSIMIST sees a dark tunnel
An OPTIMIST sees light at the end of the tunnel
A REALIST sees a freight train
The LOCOMOTIVE ENGINEER sees three idiots standing on the tracks

Country: USA | Posts: 2606 Go to Top of Page

DanT
New Hire

Posted - 08/13/2018 :  2:58:18 PM  Show Profile  Reply with Quote
I'm working on completing some test tracks for charging. The first will be a 2W arrangement for 1S battery charging. Another a 3W system for 2S charging. To be sure it works properly, I'll have to rebuild my 1S powered BPRC GP35 road switcher, i.e., move things around to fit new parts in with the old. What engine the 2S system goes into is not known yet, either my existing BPRC AMD-103 passenger locomotive or a new SD45 or FP45 diesel engine. Also considering an F7A/F7B combination, since I'll need more room than usual.

Sorry to say this takes time and I'm never sure when I can say "done". It does look like it will work. I won't miss removing batteries for recharging.

Dan



Country: | Posts: 37 Go to Top of Page

Bernd
Fireman



Posted - 08/16/2018 :  08:14:59 AM  Show Profile  Visit Bernd's Homepage  Reply with Quote
I'm going to take a break from this experiment for now. I'll keep active in watching what you bring to the for front when you're ready. Perhaps I'll come across more info when searching for some other information. The TT scale bug has been on the side lines waving at me to get going on a module I started last year. I'll keep an eye out for your posts.

Bernd


A PESSIMIST sees a dark tunnel
An OPTIMIST sees light at the end of the tunnel
A REALIST sees a freight train
The LOCOMOTIVE ENGINEER sees three idiots standing on the tracks

Country: USA | Posts: 2606 Go to Top of Page
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