Re: Passive battery switch RFID


thanks for your input guys. I havent been able to come online due to
power outages caused by hurricane wilma.

anyway. the reed switch mentioned would work, but the distance is the
issue. I currently have an rfid reader and passive tag, but they too
work only within a few inches. What I need is for the device to be
activated within 5 feet of the receiver and from my understanding a
reed switch cant do that.

I know electronic toll payment systems seem to conserve battery, and
thats what i need. Bascially I want to have a battery in the unit, but
I dont want the battery to be connected until we're in that range. The
reason passive devices dont work is because even though the antenna can
provide an induced current, without a battery the tag doesnt have enough
power to be able to transmit over say a few inches, let alone five feet.
So we need battery in the transmitter. The user only carries a
transmitter, so it doenst know when it is within range. I have a
microcontroller that will transmit an ID as soon as it is powered up,
but I dont want it to be on at all times, and I dont want a switch.
I'll look into the "Hall Effect" now and see what its about.

Thanks again guys, keep it coming.


--
fh03
.

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