You know, I'm not resonating the receiver.  So then my first question si
does it need to resonate at the same rate as the transmitter?


Shawn Wilton
Junior in CpE
MicroBiologist

Phone: (503) 881-2707
Email: shawn@black9.net

http://black9.net


Russell McMahon wrote:
>>Has anyone done anything like this app note:
>>http://ww1.microchip.com/downloads/en/AppNotes/00232a.pdf
>>
>>I'm trying to do something similar to this, but I just want to be able
>>to detect a field from about 3 feet away.  But I can't get the darn
>>circuit to produce a strong enough field in the first place.
>>
>>What I'm doing is this:
>>
>>I have a simple "transmitter" that consists of a 160uH loop connected in
>>series with a microchip T4422 fet driver running at 12 volts (7812 and
>>10pF caps) and a .1uf 100 volt capacitor.
>>
>>I'm trying to detect the field with another loop probably about 50uH but
>>much larger radius and my DMM.  I can pick up a frequency change by
>>getting closer, but I can't pick up any voltage just current in the 1-3
>>mA range.
>
>
>
> Are you resonating the receiver coil?
> You will get *VASTLY* greater voltage output at resonance.
> Tune the receiver coil near but not too near the transmitter coil and then
> move further away.
>
> Also, it is not obvious from what you say whether you are resonating the
> transmitter coil either. That will also make a significant difference.
>
> Also, if you can increases the physical width of the transmitting coil it
> will help. This is a "near field" situation and while it necessarily obeys
> the laws of physics, they may not be the laws that you might expect :-)
>
>
>
>             Russell McMahon
>
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