| 摘要 |
<p>A fibre optic readout from an optic fibre (10), which receives light from a driven light emitting diode (LED) (6) and conveys it to a light detector (8), is processed by a preamplifier (U1) and a sample and hold arrangement (32,S2,R34,C2) to produce an output of 4-20 mA. This output is applied to a conventional two-wire 4-20 mA line. Power is conserved by the preamplifier (U1) being used in a variable pulse rate mode of operation. </p> |
