Simply look on the datasheet for the AT89C2051 micro-controller to see that its max allowed voltage on any pin is +7.0V and that your R9 is connected to +12V which might destroy it.
R9 should be connected to the +5V supply of the micro-controller.
Since you cannot get a logic-level Mosfet then test many of the ordinary Mosfets to find one that works with an input of 5V.
No, that won't work because the Vbe drop of the BC177 will not allow it's emitter to go below 0.7V which will cause the BC107 to remain on no matter what.
Does anybody still make a very old BC107 and BC177 transistor? I used them at the beginning of my electronics career in about 1963 (45 years ago).
Does anybody remember the old metal cases on the very old transistors? I still have some.
No, that won't work because the Vbe drop of the BC177 will not allow it's emitter to go below 0.7V which will cause the BC107 to remain on no matter what.
The transistor BC177 will be in saturation and and hence its collector voltage will not be enough to ON the BC107. Am I right? Anyway that is not safe. What about this change (refer attachment)?
Does anybody still make a very old BC107 and BC177 transistor? I used them at the beginning of my electronics career in about 1963 (45 years ago).
Does anybody remember the old metal cases on the very old transistors? I still have some.
No, because the base voltage of the BC177 cannot be lower than it's collector. If it was in true saturation, the base voltage of the BC177 would have to be apx 0.6V lower than it's collector.
No, because the base voltage of the BC177 cannot be lower than it's collector. If it was in true saturation, the base voltage of the BC177 would have to be apx 0.6V lower than it's collector.
My wife and I think I still look handsome.
Some of the pretty young nurses at the eyes surgery place were flirting with me and I flirted back.
Guess what! A few of the pretty young flirting nurses are from India.
The very old transistors remind me of my first job which was at Philips.
You don't need a zener diode. An ordinary forward-biased diode will work fine like this:
My wife and I think I still look handsome.
Some of the pretty young nurses at the eyes surgery place were flirting with me and I flirted back.
Guess what! A few of the pretty young flirting nurses are from India.
I recently had cataracts surgery to both eyes that suddenly got cloudy lenses. Now I can stare at the pretty young women and see them extremely clearly.