<html><head></head><body><br>
<br>
Peter van Hamersveld wrote:<br>
<blockquote type="cite" cite="mid:20010106203345.DECC52A04@rubellite.lion-access.net"><pre wrap="">yess, here some questions again from Peter and Egbert<br><br><br>3) how come that one we connect a (e.g.) 100K Ohm resistor to a circuit, it reads about 60K when we measure it resistance IN the circuit, and there are no obvious illegal connections? is this usual?<br></pre>
</blockquote>
<br>
Measuring a resistor in circuit will usually give you something lower than
the resistor value, because there are parallel paths of "resistance", even
if they are not resistors. A resistance meter usually works by applying
a known voltage and measuring the current, or applying a current and measuring
the voltage, then using Ohm's law to calculate the resistance (R = V/I).
Try measuring the "resistance" of a diode: in the reverse biased direction
it will look like a huge resistor (or just overrange your meter), and in
the forward direction it will give a different resistance value depending
on what resistance range you have selected on your meter. <br>
So when you are measuring in-circuit, anything that can draw current will
make your measured resistance lower, because it acts like resistance in parallel.<br>
<br>
<br>
<blockquote type="cite" cite="mid:20010106203345.DECC52A04@rubellite.lion-access.net"><pre wrap=""><br>well, that's it for this time i guess, other questions will follow undoubtedly.....<br><br><br><br><br></pre>
</blockquote>
<br>
<pre class="moz-signature">--
Scott Bernardi
<a class="moz-txt-link-abbreviated" href="mailto:sbernardi@home.net">sbernardi@home.net</a></pre>
<br>
</body></html>