Subject:
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5VDC Voltage Regulation
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Newsgroups:
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lugnet.robotics
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Date:
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Mon, 27 Sep 1999 15:02:07 GMT
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Viewed:
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492 times
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I'm in over my head with a project and need some help. I'm trying to use an RCX
output port to control a 5VDC SPDT Relay from Radio Shack (part #275-240A). I
need to limit the voltage of the port to 5 volts. How can I accomplish this?
Is a voltage regulator IC correct? Alternatively, does anyone know if putting
excessive voltage across this relay (max. VDC is listed as 6.5) for long periods
of time will damage it? I have put as much as 8.3VDC across the coil for a few
seconds without damage.
What I am hoping to achieve is a block with pairs if connectors, call the
connectors in each pair A & B. When the relay is off the A connectors are
attached to the RCX. When the relay is on, the B connectors are attached. I
need 2 pairs for a project now, total of 4 motors - only 2 of which are used at
a time. I believe the first version of this will have 3 pairs, one to be used
to control a sensor port.
Thanks,
-Wes
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Message has 2 Replies:
 | | RE: 5VDC Voltage Regulation
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| (...) The RCX puts out a variety of waveforms depending on the power level. If you have acecss to an oscilloscope, you can see that the higher power levels give you more "on time" that lower levels. The DC level at full on is about a diode drop (...) (25 years ago, 27-Sep-99, to lugnet.robotics)
| | | RE: 5VDC Voltage Regulation
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| You need to limit the current through the relay. Just add a resistor in series with the relay. You can experiment, using a voltmeter, or you can calculate the proper value from the relay specs. Relays specs usually list the resistance of the coil. (...) (25 years ago, 27-Sep-99, to lugnet.robotics)
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