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Forum Index : Microcontroller and PC projects : Enclosure with charging contacts...
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| PeterB Guru  Joined: 05/02/2015 Location: AustraliaPosts: 655 |
Good morning CB (well it is for you) Looking at your video again I am more confused than ever. From the data sheet posted by Grogster, the receiver has a metal / ferrite / whatever core not the transmitter. Peter |
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CaptainBoing Guru Joined: 07/09/2016 Location: United KingdomPosts: 2170 |
@PeterB The transmitter has a circular ferrite disc which is bonded to a circular cloth insulated (cotton?) coil. The receiver is an enamelled oval, copper coil. I have seen some with a small metal insert in the middle but mine are a simple coil with an air centre. Would you like me to do some pictures and post some close-ups? If you tell me what specifically has caught your eye, I'll try to cover that specifically all the best |
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| PeterB Guru Joined: 05/02/2015 Location: AustraliaPosts: 655 |
Good whatever it is there CB. I got confused by what is transmitter and what is receiver. Your system has a lump on the transmit coil but the data sheet shows one on a receive coil. It gets murkier and murkier. There are several sub types of contactless charging but they are basically low frequency or RF. Yours look like LF. They seem to use a ferrite plate on both coils but on this I am not clear in fact, I'm starting to think I've got no bloody idea. I did give up on Banggood after they sold me 20 PSUs all dud so I have no confidence in them. One interesting thing I discovered is, Nancue's tooth brush actually uses an iron core. There is a long flat U shaped magnetic core from the base station to the brush which slips over a peg containing the second pole of the transformer. That is clever and is it applicable to what you want? That's my rant for the morning. Peter edit. My wife is Nancye not Nancue. (I wonder who she is?) |
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| CaptainBoing Guru Joined: 07/09/2016 Location: United KingdomPosts: 2170 |
 My Nancue has a toothbrush the same design as that. I never dismantled it (on pain of moaning) but the basic concept is fairly obvious so I never really had much desire to open it up... until now.  Yeah, I didn't choose great terminology for the two bits... let me clarify. By "transmitter" (Tx) I mean the half that is always powered up and provides the magnetic field for the second bit ("Receiver", Rx). The coil assembly on this Tx consists of a circular ferrite disc about 2mm thick with the cloth insulated coil bonded to the surface. A red LED indicates a 5V power source is present, a blue LED indicates "charging" - i.e. there is a transfer of energy taking place from the coil. There is a bit of lag with this coming on and again when the Rx coil is moved in and out of proximity. I reworked the board to move the LEDs to the other (component) side and changed their current limit resistors to 1K as I got a nasty letter from the CAA... something about confusing aircraft bound for LTN... The Rx is the bit that goes in the mobile device and takes the mag field and chucks electrical power out. It is an oval coil with an air centre. The wires of the coil appear to be doubled up - possibly a current consideration? The Rx gets quite warm when it is operational and using an adjustable load, I have determined from simply sticking my finger on it that it is more or less the same temperature regardless of the current draw. The hooting that you see in the stills from my scope shows a total collapse of the output voltage - the spikes are the full 5V. They occur is groups and the individual spikes within the group are up above 500KHz - so it might be RF transfer but I really am at the limit of my understanding of these devices here (hey, I am a programmer and digital man at heart). I am away from home at the moment but will be back tonight - I'll see if I can get some shed time and do some close-ups that will help with the understanding of the ramblings above. all the best h |
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| PeterB Guru Joined: 05/02/2015 Location: AustraliaPosts: 655 |
Back again. I think I understand your video now. I thought it was all sorted out by the data sheet showing the receiver with a core and then you come along with a core in the transmitter. That is a bit inconsiderate of you. I liked the idea of a core in the receiver because it is like a 2D loopstick if you remember those. On the subject of what we like, I'm a hardware bloke but I did enjoy using ASM because it's about as close as you can get to "real" electronics without the hard work but the world moves on. Peter |
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| CaptainBoing Guru Joined: 07/09/2016 Location: United KingdomPosts: 2170 |
Yeah I'm a stinker... I'll try to do better Oh yes... assembler is my first love... a dream for me would be to find a really fast Z80-core microcontroller. There are various Hitachi ones that come close but (and I can't remember why just now) I never made the jump. I reckon a Z80 running at 3GHz would be fairly spectacular, but the modifications to get away from the (now) tiny memory map would make it feel alien... dunno. an old man's fantasy |
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Grogster Admin Group  Joined: 31/12/2012 Location: New ZealandPosts: 9610 |
UPDATE: The wireless charger thing was a nice idea, but it is simply not reliable. The positioning of the receiving coil on the charging base pad thing has to be EXACTLY right to achieve a decent current charge. This is with the little stick-on shield thing over the coil, to help 'Focus' the inductive coupling. If the coil(and by extension, the product) is not placed on the charger in EXACTLY the right place, the charging is either extremely slow(100mA or so), or so bad that the charger keeps dropping off all together so the battery never actually charges up. Even at best, the charging current is only around 500mA-600mA, but if I plug a 5v USB charger directly into the micro-USB socket, I get the stated 1A charge current as expected. It was a nice idea, but it simply is not working out how I planned, and I have visions of the client complaining that the thing never charges up - cos they have not put the thing on the charging pad in EXACTLY the right place. So I am back to looking for a case with charging contacts. I am reviewing all links posted on this thread by other members, but what would be ideal, would be something I can buy off the shelf without having to invent my own. Don't really want to use a socket on the side of the case, but I will - provided I can find a small waterproof one. I am looking for something along those lines now. I need the unit to be at least splash-proof, preferably water-proof. That is why I don't really want to drill holes in the case for a charging connector - it can(and probably would) leak. Smoke makes things work. When the smoke gets out, it stops! |
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TassyJim Guru Joined: 07/08/2011 Location: AustraliaPosts: 6283 |
What about the contact system used for most cordless phones that sit into a cradle and make contact. Doesn't always work but 99% of the time they manage to sit in correctly. I power LED either on the cradle or device to let you know when contact is made. Jim VK7JH MMedit |
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9610 |
Its funny you should mention that, I have just been google searching that very thing!  Great minds think alike. There are some very cheap cordless phones at discount stores, so I will look to get one or two of those, so I can gut the handset and design my board to fit in there - perhaps. The only thing is all the buttons etc, but I suppose I can just ignore them. Food for thought, anyway. Smoke makes things work. When the smoke gets out, it stops! |
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| PeterB Guru Joined: 05/02/2015 Location: AustraliaPosts: 655 |
Good afternoon Grogster et al 1. I am surprised that the coils have to be lined up so accurately. 2, C.B and I had a side conversation about the electric tooth brush. They use a magnetic core that the brush fits over but I have no idea about power flow. 3. You started with a requirement for weather proof, cheap cordless phones? Peter  |
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9610 |
I have found you can get sets of charging contacts. This may well be a way around this problem. LINK... They are held together with magnets, so they should lock on pretty good and stay there for a good contact etc. I might be able to design something around these. Smoke makes things work. When the smoke gets out, it stops! |
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| BrianP Senior Member  Joined: 30/03/2017 Location: AustraliaPosts: 292 |
If you want to stick with wireless charging, make a cup-shaped receptacle fixed to the charging pad to hold the device in the right spot. Interestingly, the in-car wireless charging pads for phones don't seem to have a very tight position requirement - they are quite broad in area. The electric toothbrush charging systems do lock in the positioning as per my suggestion above... The "field of charge" area is quite likely related to the frequency used & therefore the size of the coils - lower = wider. Just my 2c worth...  B |
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Quazee137 Guru Joined: 07/08/2016 Location: United StatesPosts: 593 |
Grogster was looking for a few items at globalsources and found this. |
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| Quazee137 Guru Joined: 07/08/2016 Location: United StatesPosts: 593 |
I flubbed up with link  (Glen I LOVE the NEW look and feels like home already. I need edit post to cover up my flubs) globalsource |
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9610 |
Thanks for the link!  These might be perfect, as they come complete as a set. I will buy a few samples. Smoke makes things work. When the smoke gets out, it stops! |
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| Tinine Guru Joined: 30/03/2016 Location: United KingdomPosts: 1646 |
Hey Graeme, I don't know if you are still looking but I think I am going to try some of these for charging my HMI tablets (I only need power to the micro USB): These are the bigger ones, they have others, up to 6 contacts. |
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