Please tell us what this part of the circuit is supposed to do.....more info and stuff needed.
It just looks like.....what's it's purpose? Unless of course the Diode is a supposed to be a LED....which gets turned on when the transistor switches on and grounds the +12V through the "diode" and the 2.2K resistor. 2.2K resistor is still waaay to high to light up any LED from a 12V supply.
Ib= (12V-0.6V)/100K = 0.114mA
Ic= (10.6-.2)/2.2K = 4.72 mA
4.7ma will easily light an LED
current gain = Ic/Ib = 4.72mA/0.114mA = 41.46 easily within the HFE of common transistors.
Using TINA it says 4.28 not enough for LED to light but TINA may be wrong?
I inserted a switch across the transistor to verify saturation. With switch closed the current shows very little change.
Ib= (12V-0.6V)/100K = 0.114mA
Ic= (10.6-.2)/2.2K = 4.72 mA
4.7ma will easily light an LED
current gain = Ic/Ib = 4.72mA/0.114mA = 41.46 easily within the HFE of common transistors.
if i have an led that needs to be lit from 12v i would use a 2.2k ohm resistor. it is also what velleman suggests to use on the back of their 80 led packet for 12v and use a 470 ohm if its 5v.
The led will light up. that is all that will happen with that circuit. you will probaly find though that the 12v input will be switched on and off as a signal
I like my LED's to be driven properly. Either on or off. Not in "low power mode". LED's are supposed to indicate the status of a system. And warn you with bright flashing lights.
The LED reports the status is either good or bad guys....
So, at what current is "on" for an LED. I frequently use, and see, status LEDs running at currents >10mA. I've used super bright LEDs for status indicators at 1ma on battery devices. Definately shows on or off status. Why waste power.
So, at what current is "on" for an LED. I frequently use, and see, status LEDs running at currents >10mA. I've used super bright LEDs for status indicators at 1ma on battery devices. Definately shows on or off status. Why waste power.
No, it's not "bright". But it definitely shows an on/off status. I've also used low brightness as a status..."the LED works!", "these is power!"...high brightness then indicates a change in status.