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Hello all,
I recently purchased "Extreme Mindstorms - An Advanced Guide to LEGO
Mindstorms" and I must say it is one of the best books out there for the
power user.
I have a number of questions regarding powered sensors. First of all, when
the RCX goes to make a the reading on a powered sensor it drops the output
voltage from 7 to 5 volts, and then takes a reading. Does the RCX take
into account the two diode drops (D5 or DG and D1 or D2) I would assume
that it must, otherwise when the leads are shorted it would still be reading
1.4 volts... which is not correct. So I would assume that there is some
form of offset in the RCX or something?
also, in figures 10-5, and10-7 (in all the powered sensors for that matter)
what is 1K resistor used for? it appears to be some form of current
limiting resistor, but from understanding of the internals of the RCX, there
is a 10K resistor in series with it.
If anyone can help answer these questions it would be greatly appreciated,
thanks.
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Message has 1 Reply:
 | | Re: Powered Sensors
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| No, the RCX knows nothing about the diodes. That is why devices like the light sensor only send a current signal in the range 0 - 0.32mA back to the RCX. This current then creates a voltage drop across the 10k reference resistor with respect to the (...) (22 years ago, 7-May-02, to lugnet.robotics.rcx.legos)
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