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OSH Park
15362^0
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15362^0
by![](../../gravatar.com/avatar/66f6518df570ceb1348543eaae5c1651ea98.jpeg?s=16)
2
layer board of
0.90x0.55
inches
(22.89x13.97
mm).
Shared on
February 13th, 2016 07:51.
HT
This simple circuit transmits a 3mA or 10mA current loop value as a pulse, it is controlled with the venerable 555 timer connected to a capacitive moisture sensor and a thermistor. The current loop flows in a CAT5 pair that provides well-known transmission line effects and superior noise immunity. The current sensing resistor is also a termination for the transmission line.