Thanks Nigel for the advice. About what gramo says, when you say a smaller Vce voltage drop, that is a value as closer to zero, or to be a negative value (...)?
Sorry guys, but im still not so sure bout all..
The pic16f84a gives 5v 100ma as output to PortB. one pin of it will give around 12.5ma -100ma/8 pins-.
(5v - 0.6v)/12.5ma = Rb = 352ohm, according to gramo.
What i did before was this:
I took for example Ic = 10ma; Vce = 10v for a hfe = 75 from the datasheet
Vce = Vcc - Ic*Rc ; Ic = hfe*Ib ; Rb = (Vbb - 0.6)/Ib
at the end i found that Rc = 1k, Ib= 0.13ma and Rb = 33kohm.
Here i face 2 issues:
1) Im not sure if i must count the current out of the pin (..12.5ma) in the equation.
[Ref
**broken link removed**
2) Rc as i see it = (2888ohm coil *1000ohm led )/(2888+1000) = 742.8ohm
correct me if im wrong, i took the 1n4004 as open and LED as short,
where input Vcc = 20v , around 75% of max rated voltage for the coil 24vdc - thus the LED resistor is 1kohm for a 20ma current drive (max is 30ma for LED)
[Ref
**broken link removed** look for "Relay + LED monitor" ]
I just want to be sure about the procedure, i have to defend this project in a week and explain all posible details.
Hope you ppl can enlighten me up
and thanks again
By the way, i want to apply that green coatin on a pcb. Do you know any brands of that material so i can buy it, and/or the procedures involved in the aplication of it. Ive read its called solder mask, but the procedures are blur to me
, just a couple: removable solder mask and some vitrea paint curing
Pebeo Vitrea 160
**broken link removed**