Limit Switch Adapter
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LSA Limit Switch Adapter
Listed here for reference only .
Use Lego switch sensors as limit switches, without
an RCX sensor input!
The Limit Switch Adapter is for use with the Lego Mindstorms™
Robotic Invention System.
It lets you use a standard Lego sensor switch as a limit switch.
A limit switch will automatically stop a motor when it reaches the desired
position. The Limit Switch Adapter will allow you to do this without
using an RCX sensor input. This is a good way to learn
about limit switches.
Limit Switch Adapter .
In the picture below, a single switch is used to stop the crossing gate
in it's raised position.
Size: 2 bumps by 8 bumps. Height is one and one third brick.
(brick plus flat plate).
Lego electric plate connector on bottom.
Two switch inputs to stop at both ends of travel.
Works with any polarity.
Works with all Lego motors.
Works at all Mindstorms motor power levels.
Motor braking when the motor is turned off.
Arc surpressor protects relay contacts.
The Lego switches send current through a diode to an opto-isolator.
The opto-isolator controls current to a relay. The relay controls
power to the motor. A capacitor stores power so the relay does not
chatter when Mindstorms is set for low power output. A second set
of contacts on the relay is used to short the motor terminals when the
motor is turned off. This provides a braking function, so movement
stops immediately. Back-to-back zener diodes prevent arcing when
the relay opens, extending the relay contact life. The entire circuit
is designed to minimize power drain when the motor is switched off.