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Getting near a wire on circuit causes current to go to 0A

E

Eric H.

Jan 1, 1970
0
I have a TRF-2.4G wireless transceiver,
http://www.laipac.com/easy_trf24_eng.htm, from Laipac and I'm having
a strange problem. Most pins seem to work fine, but one acts very
strangely. If I have a wire hooked up to it, even putting my hand a
few inches away from it will cause the current to the device to drop
to zero. Even just having the wire plugged into a breadboard will
cause this problem. I tried plugging it into ground, same thing.
However, connecting it to VCC made it stable, I could even touch the
wire and no problem. That doesn't help me though as I need to keep
that pin low most of the time.

This particular pin is used to tell the device that data will be
either transmitted or received. A similar pin, that tells the device
when it is to be configured, doesn't behave this way.

Any help you can give would be appreciated. Please let me know if you
need any more information.
 
E

EEng

Jan 1, 1970
0
I have a TRF-2.4G wireless transceiver,
http://www.laipac.com/easy_trf24_eng.htm, from Laipac and I'm having
a strange problem. Most pins seem to work fine, but one acts very
strangely. If I have a wire hooked up to it, even putting my hand a
few inches away from it will cause the current to the device to drop
to zero. Even just having the wire plugged into a breadboard will
cause this problem. I tried plugging it into ground, same thing.
However, connecting it to VCC made it stable, I could even touch the
wire and no problem. That doesn't help me though as I need to keep
that pin low most of the time.

This particular pin is used to tell the device that data will be
either transmitted or received. A similar pin, that tells the device
when it is to be configured, doesn't behave this way.

Any help you can give would be appreciated. Please let me know if you
need any more information.

Ground it through an RC tank. Play around with the values.
 
R

Robert Baer

Jan 1, 1970
0
Eric H. said:
I have a TRF-2.4G wireless transceiver,
http://www.laipac.com/easy_trf24_eng.htm, from Laipac and I'm having
a strange problem. Most pins seem to work fine, but one acts very
strangely. If I have a wire hooked up to it, even putting my hand a
few inches away from it will cause the current to the device to drop
to zero. Even just having the wire plugged into a breadboard will
cause this problem. I tried plugging it into ground, same thing.
However, connecting it to VCC made it stable, I could even touch the
wire and no problem. That doesn't help me though as I need to keep
that pin low most of the time.

This particular pin is used to tell the device that data will be
either transmitted or received. A similar pin, that tells the device
when it is to be configured, doesn't behave this way.

Any help you can give would be appreciated. Please let me know if you
need any more information.

There is too much RF in/around the device (and the pin in question).
The RF may be biasing the device due to detection by the protection
diode(s) at the device input (if an IC, right under the bonding pad).
Excessive RF can damage the unit.
You need to do some shielding and RF damping...
 
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