APF Spectrograph Electronics
Board Designs
Triple Haff-Effect Limit Board with Reverse Switch Inverted, 
EL-1394
Schematic: schematics/APF/boards/limit_board.pdf
Page last updated: February 8, 2012
Simplified Drawing
The EL-1394 circuit board simply contains 3 Cherry VN101501 digital vane switches and a 2N4401 transistor. The transistor is used to invert the sense of the reverse limit switch. While this board was originally used on the Dewar Focus stage, the latest version of that stage now requires that both the forward and reverse limit sense be inverted. The switches are spaced at 0.8" between forward and reverse limit and 1.0" between the reverse limit and Home sensor. The board has a 6-pin connector, J1, that supplies +5V and GND and four output pins. The outputs correspond to the three sensors and a limit connected signal. The LIM CONN signals the controller if for any reason the connector has been disconnected.
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