27-05-2013, 08:44 AM
(This post was last modified: 27-05-2013, 08:57 AM by camallison.)
(27-05-2013, 07:08 AM)boiss Wrote: I'm going to knock up a system to charge the batteries and power the radio (Hacker Sovereign) wirelessly. (My radio has no socket for external power and I am not going to modify it) This will mean that the radio must be put in a cradle or on a plinth for the system to operate. One thing I have been thinking about is the frequency to use because this will be quite a powerful signal (around 20W). Keeping away from frequencies that multiply up to the IF is the obvious one, but are there other frequencies to stay away from? In the Hacker instance there are 2 batteries, while each will have 6 nicads, they will also need their own coupling/charging cct.
Due to the high cost of power microwave devices I guess this system will need to work in the LF region 25KHz to 150KHz.
Any suggestions, has anyone done this already for their equipment/radios?
Mike
If you know anyone with one of the Oral-B rechargeable toothbrushes, you might "sniff" around that and see what frequency they use. Unfortunately, the only one we have has already been hacked by me, and won't repair. They have a coil in the base and a similar one on the toothbrush handle that couple to transfer the power. Looking at the one in the toothbrush, it is a few hundred turns with a centre tap. The converter/charger circuit is tiny with SMD chip and other components. The chip type info has been covered with "goop" so I can't see what it is.
The cell that is recharged in this case is a NiMh 3/4 AA-size cell. Later models have a Li-ion cell instead.
Colin
[UPDATE - found that SWMBO has bought a new one and, on pain of untold agonies if I broke it, I have sniffed around the base charger and the frequency is 100Hz with a fair amount of harmonics too. Obviously it would need some extensive scaling up for the Hacker set.]
