I have updated the schematic/layout to include the BC817 transistor (SMD).. and made a quick board layout for it (simple enough)
I have a couple of 'dumb' questions.. some about transistors in general (and those darn datasheets).. and one about extending this with the Arduino..
as you can see its a fairly easy/simple schematic & board design.. (not much to it).. just a pcb of leds for the Arduino to 'control'..
looking at the datasheet for the BC817 transistor.. (http://www.datasheetcatalog.org/datasheet/philips/BC817_3.pdf
I get confused at to the 'numbers' given because of the naming conventions used.
basically a transistor will allow a 'higher' voltage/current pass through it (to the target device)....(unaffected..ie: not regulated or anything)... by allowing a 'smaller' voltage/current to 'toggle' the gate and allow said 'flow'...
Collector Base Voltage Max:
Collector Emitter Voltage Max:
Emitter Base Voltage:
(these names are confusing me)
1.) Emitter Base = Base?.. ie: the Arduino 'toggle/gate' control pin?
2.) Collector Base = Collector? (out to leds/device)
3.) Collector Emitter = Collector? (GND from battery -)
(Vcbo) Collector Base = 50v
(Vceo) Collector Emitter = 45v
(Vebo) Emitter Base = 5v
Does that mean it can have up to 50v connected (from battery/source)...
output up to 45v to the 'target' device..
and can take 'up to' 5v (max) to toggle/control the gate?
4.) Im also confused about the current ratings given.. it is 200mA available or 500mA available? what are the difference between the two numbers given?
(Ic) Collector Current = 500mA
(Ibm) Peak Base Current = 200mA
I have a question about usability and the Arduino.... using the same schematic/board files from above...
If I had two of these pcb's.. (each with a transistor, leds..etc)
could I connect this 'second' pcb in series to the first?
basically jumper/bridge from the battery +/- pads from the first pcb to the second.....
but more importantly.. could I use the same PWM pin to control/fade BOTH pcb's at the same time??
** and lastly (last question)
I had asked above.. but I dont think it was addressed/answered...
the current footprint of the LEDs are 1206 package.. this is not set in stone (all resistors will be based of the battery source and vF of the leds when finalized.. although Im sure the leds are still just white in color)...
a thought was to use the 5050 package leds.. (these 505 leds are really 3-separate leds under 1 housing/dome..
the 5050 leds have 3 GND pads.. and 3 POS pads (ie: set for each led)..
in this application.. the 5050 unit will be treated a WHOLE unit/led.. in respect that the GND pads will be bridged.. and the POS pads will be bridged.. on the 5050 led itself.. (with traces on the PCB)..
still only using "1" resistor per led.. (but now this is a 5050 packaged led)
these 5050 leds (I believe) take 60mA!! (3 x leds in eahc unit, 20mA each, 3 x 20 = 60mA)..
my question is.. if the one resistor I use, limits the current to, say, ...40mA going to the 5050 led/unit... how will the leds respond/behave?
Will all 3 leds split the '40mA' equally? will one leds take more? or full mA leaving the others without full or equal current?
in the current example. if I changed to 5050 leds.. there are 5 leds.. going to all 5 x 5050 leds would be (5 x 60mA = 300mA) neded per pcb/board!!
Im not even sure the transistor can handle/provide that?.. however if @ 40mA each 5050 led looks and acts fine.. it might be a viable option... (or maybe just more 1206 leds!) lol.. but I 'am' curious.