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ETag board: Back side, towards MICAz.
Push buttons.
Photo-interrupters.
About 1mm over the
board edge.
• Current limiter resistor
for photodiodes. Jonathan
suggested 330 Ohm, I
made one up from two
pieces.
Push area: 1.5mm high
and 2mm wide.
Push distance: tiny
(under a mm)
• Switch-on transistor
DigiKey data:
401-1101-1-ND
SWITCH TACT 250GF
GULL SMT
• Phototransistor load
resistors for the two
“Right” photo interrupters
(installed 470K, adjust as
needed)
Bypass capacitor for the pulseox sub board
Resistor: 0 Ohm. Enables power-on for the Pulseox sub board. Can
be removed and a switch transistor installed so that the pulseox sub
board power is enabled from software.
51pin connector to MICAz.
ETag board: Back side, towards MICAz.
Place for LCD contrast potentiometer (not
a user control, but just for adjustments)
Connectors to the Pulseox sub
board
Two photo interrupters:
TR and BR (top-right
and bottom-right)
Pulseox sensor /
RS232 serial
connector
LCD (version
1b board does
not support
LCD, version
1c does).
LEDs
LED switch components
RS232 level conversion circuit, not
populated (alternative option to the
Pulseox sub board feature)
Two photo interrupters:
TL and BL (top-left and
bottom-left)
Photo transistor load resistors for the
two “Left” photo interrupters
(installed 470K, adjust as needed)