# Wireless phone charger

Started by February 24, 2020
```Just for fun I thought I would make a wireless phone charger. I'm not reall=
y going to use it but I wanted to build it and just see if it actually work=
ed. The circuit uses two coils and a 2n222 transistor very simple.

Well I can't really get it to work maybe I could get half a volt maybe to p=
ast through induction. Then it seems to stop. I connected my meter to the r=
eceiving coil to test.

I was using 30 gauge wire which I had although the circuit calls for 32 ga=
uge that may be part of the issue.

However my question is , as I began to think about it and a little bit of =
science that I know is that induction I thought had to be AC current becaus=
e there had to be movement caused by ac going up and down. The circuit as f=
ar as my reading however puts in 5 volts DC in the Base unit and passes it =
to the receiving coil. I'm not sure if that's going to work?

The question then is, in a simple circuit can you use DC in induction.

Thanks
```
```On 24.02.2020 18:27, Steve Wolf wrote:
> Just for fun I thought I would make a wireless phone charger. I'm not really going to use it but I wanted to build it and just see if it actually worked. The circuit uses two coils and a 2n222 transistor very simple.
>
> Well I can't really get it to work maybe I could get half a volt maybe to past through induction. Then it seems to stop. I connected my meter to the receiving coil to test.
>
>   I was using 30 gauge wire which I had although the circuit calls for 32 gauge that may be part of the issue.
>
>   However my question is , as I began to think about it and a little bit of science that I know is that induction I thought had to be AC current because there had to be movement caused by ac going up and down. The circuit as far as my reading however puts in 5 volts DC in the Base unit and passes it to the receiving coil. I'm not sure if that's going to work?
>
> The question then is, in a simple circuit can you use DC in induction.
>
> Thanks
>
No, you can't use DC here. In fact you should not have any DC on the
coil... If you put DC in it you would get an electromagnet (or a lot of
smoke). What frequency are you driving your coil at? How many windings
does the each coil have?

QI chargers usually work at between 100 and 200 kHz for low power and
~500kHz for medium power.

Cheers, Nife

```
```https://youtu.be/QPL37V7JDNQ

Here is the utube video.

I have looked for for diagram but can't find one.

Perhaps I misunderstand the ac adapter he is using but it looks like an ac/DC adapter.
```
```PS base is 15 x 15 and recever is 20
```
```On 24.02.2020 19:45, Steve Wolf wrote:
> https://youtu.be/QPL37V7JDNQ
>
> Here is the utube video.
>
>
> I have looked for for diagram but can't find one.
>
> Perhaps I misunderstand the ac adapter he is using but it looks like an ac/DC adapter.
>

It's VERY sketchy and the way they did that I'm not sure how long will
the protection diodes in the phone hang on. Having said that, the
transistor with two coils forms a flyback transformer running at some
unspecified frequency. So that takes DC and generates AC. Again, the
video implementation is super shady. More on flybacks here
```Thanks for your comments.