The design has ripened to the extent that a real PCB can be presented to start experimenting for real.
Experimental Node
Resistors
R1,R8 = 680Ohm
R2,R3,R6 = 10kOhm
R4 = 120Ohm
R7 = 2.2kOhm
R9,R10 = 4.7kOhm
Capacitors
C1,C2 = 22pF
C3,C4,C8 = 4.7µF
C5,C6,C7 = 100nF
Semiconductors
D1 = 1N4004
IC1 = ATmega88-20PU
IC2 = LT1785
IC3 = 78L05
Miscellaneous
X1 = 16MHz quartz crystal
S1,S2,S3 = pushbutton
JP1,JP2= jumper
LED1 = LED, 3mm, red
LED2 = LED, 3mm, green
LED3 = LED, 3mm, yellow
K1 = 6-pin (2x3) pin header, lead pitch 2.54mm (0.1 in.)
K4 = 8-pin pin header, lead pitch 2.54mm (0.1 in.)
K2,K3 = 4-way PCB screw terminal block, lead pitch 5.08mm (0.2 in.)
PCB # 110258-1
USB/RS485 Converter
Resistors
R1 = 10kOhm (0805)
R2 = 120Ohm (0805)
Capacitors
C1,C2 = 100nF
C3 = 10µF 16V (6032)
Semiconductors
IC1 = FT232RL
IC2 = LT1785 (SO-8)
Miscellaneous
JP1 = jumper
K1 = USB socket Type A
K2 = 3-way PCB screw terminal block, lead pitch 5.08mm (0.2 in.)
PCB # 110258-2
or
ready assembled and tested PCB # 110258-91
Books
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