I'm building a 40 yard dash timer and I was going to try and communicate via Bluetooth but the signal is too weak to send that far. Trying to find type of cable to send power to other electronic circuit at the end. I thought about using CAT5 but haven't found any cable configuration table that shows which color wires (green, orange, brown) are used for power (if applicable), Tx, or Rx. If you guys happen to know some cables or wire that is worthwhile please let me know!
CAustin:
Oh okay. I was wondering if that was the case. Great to know! Thank you so much. All I would need now is to get the female jacks and I'm all set!
The RJ45 connectors are not designed to carry power. You would be better off to use one pair for TX data, one pair for RX data, and one pair for + power and one pair for - power. And use some type of screw terminal connections.
For the price of the cable, you could literally buy 2 boards, 433MHz link set, an optical sensor break-beam setup, AND the batteries to run them. Think about that.
@ INTP: I thought about your recommendation using the 433 MHz rf link set but wouldn't it be better to use the 2.4 GHz transceiver? I say this because I would need the finish line arduino to send a signal back to the start arduino to stop the timer and send the signal of when the runner passes through the sensor.
Paul_KD7HB:
The RJ45 connectors are not designed to carry power. You would be better off to use one pair for TX data, one pair for RX data, and one pair for + power and one pair for - power. And use some type of screw terminal connections.
Paul
Not heard of PoE (power over ethernet)? Yes the connectors can carry power, but not crazy amounts. You'd
be best regulating at the point of load and having a larger voltage on the wires for a long distance cable. IE
supply 12V down the cable to the Vin pin.
Use one pair for data+gnd, then 6 other wires free for power, for instance. Every signal wire must be paired
with a ground wire, note, and for long distances terminate at the receiving end with two 270 or 220 ohm resistors, one to ground, one to +5V.
[ BTW the initial PoE specification is for 0.35A per wire, more recent ones upto 0.6A per wire (which
may assume superior connectors of course) - I think 0.3A isn't going to cause any problems with
any RJ45 connector out there ]
Always use the twisted pairs in pairs. If you need power and ground, use one pair.
If you need more power (because the voltage drop is too great over a long cable) then put power and ground on another pair. Don't use both wires in a pair for just power or just ground.
If the voltage drop is still too much then use a higher voltage. Like: power the project from a 12V battery and send 12V down the cable so the Arduino at the other end has to use the DC-in jack. That way even if you lose a few volts on the long cable, the regulator at the other end can still make clean 5V power.
CAustin:
@ INTP: I thought about your recommendation using the 433 MHz rf link set but wouldn't it be better to use the 2.4 GHz transceiver? I say this because I would need the finish line arduino to send a signal back to the start arduino to stop the timer and send the signal of when the runner passes through the sensor.
Starting point- timer starts.
Ending point- beam breaks, sends message back to starting point.