I can't find low droup out regulator on TO-92 package. Only found high droup out regulators in TO-220 case. Can i use a general optocoupler and a general transistor (Or TL431) as a BC....used here? What might be the efficiency? I need 5 V from 6 or 9 or 12V source.
Almost EVERY semiconductor manufacturer makes a 5V low-dropout voltage regulator in a TO-92 case. I used a National Semi LM2931A-5.0 in my FM transmitter only because I had a bag full of them. National Semi also makes a few more.
A 3.3V zener diode is a poor voltage regulator and an LED is also a poor voltage regulator. Their voltage drops when they get warm and when their current drops.
A 6.8V zener diode is a good voltage regulator if the input voltage does not drop too low (it is not low-dropout).
The circuit you found uses the transistor as an on-off switch with nothing limiting the current in the zener diode and LED.
Almost EVERY semiconductor manufacturer makes a 5V low-dropout voltage regulator in a TO-92 case. I used a National Semi LM2931A-5.0 in my FM transmitter only because I had a bag full of them.
But may be my life will be end with searching equivalent (replacement) of each and each components . A component which is not used on general TVs and radios, that is impossible to get here!
I said before I have been searching a heatsink of TO-39 from 2 yrs, even can't find! Planning to make myself by melting aluminium in fixed shape! So being mechanical engineer leaving electronics engineer
But may be my life will be end with searching equivalent (replacement) of each and each components . A component which is not used on general TVs and radios, that is impossible to get here!
I said before I have been searching a heatsink of TO-39 from 2 yrs, even can't find! Planning to make myself by melting aluminium in fixed shape! So being mechanical engineer leaving electronics engineer