hello, yes 9 wires = 9 solenoid + pin 25 of D-sub is'nt connected yet to 24v
the valve datasheet has too many configurations they dont specifiy electrical details in the specification (just 12v,24v, ac/dc , wire connector types)..
although in some configurations i can find pictures of electrical features
Protection Diodes:this is question mark for me now, i'll explain why:
its (common positive common negative) valve
i mean yeah they can put 2 leds like this (i found in some pictures in their datasheet):
so im assuming this (zener diode should protect against the back emf of the solenoid ?? or they rated to 24v and the
back-emf voltage will reach to -24v to my 3v3 mcu and burn it so i should use diode?
Current:current i did put DC supply and it showed that it take 20mA which is in my opinion very low...
(or the power supply is not accurate) .. but then i can see this in the datasheet of the valve:
Base Resistor:im using Bipolar (BJT) Transistor NPN 45V 800mA 100MHz 300mW Surface Mount SOT-23-3 (TO-236)
so i thought i will use resistor to limit current in base:
i assume
Hfe = 200
Ic 30mA -> Vbe = 0.7v @ 25C
Ibe = 30mA / 200 = 150nA
R ~= 17K
thats right ?
What about replacing all transistors with an IC such as the ULN2803A or ULN2003A?
thank you, i will need to research about darlington transistors and how they work, should i connect external resistors or not ...
for now im going with this "bulk of transistors" because i bought them allready from digikey .. but i'll need to edit the circuit later after my first revision ..
how about Traces of the pcb ? components location? and most important this "programming JTAG" there is way to get rid of it ? i just want to flash SAM-BA into the mcu and then always use USB as programmer..