I thought this was interesting
IMG_20250925_091617691 (1).jpg
I had been doing these exercises where maximum voltage swing is calculated then tested in these single stage (?) circuits. And I have been very impressed that calculations match the test results :tu:
But what intrigued me is that apparently if there is an un bypassed emitter resistor then the out of phase output signal 🚦 will be limited by the input signal at the emitter junction.
IMG_20250925_091624501 (1).jpg
I really want to do this and watch both signals on my scope. I need to set the DC on both to get them where they need to be or rather at zero before starting.
whats a trip is trying to imagine what actually physically how this takes place
So I decided to try and replicate this xP
First I didn't have the exact components so I cobbled a few together and my calculations went awry until I increased the base resistor
IMG_20250925_215128543.jpg
Then the numbers started to make sense so the birds nest was assembled
IMG_20250925_215106894.jpg
I had to go back a few times and zero out each channel so it would be reading correctly but it seemed to work.
IMG_20250925_215214145.jpg
Another problem was the trigger was not working it was scrolling from left to right despite my efforts I got it to stop at the lower volts per division ➗ but as the units were increased it got unstoppable
IMG_20250925_215230350.jpg
IMG_20250925_215426692.jpg
At the end I wanted to measure the max input and it was about 0.5 Vp-p
IMG_20250925_215636771.jpg
I really thought I was up the creek when I started to try and put this together :grr
That's a real eye opener that the original 1.4M base resistor calculated that all the voltage would get used up at the collector resistor :grr
I guess I need to figure out or learn why that would be like a dead short for Vc-e and Vre but my head is spinning right now :lmao:
I'm not sure what you meant about getting the DC right for the scope, but if you switch the channels from DC to AC coupling you won't have to worry about that.
Yes sir thanks all I meant was this
IMG_20250925_215636771.jpg
This is the input signal and at 0.5 volts per division that puts the centerline at about 1.6 which I hope is about correct relative to the vertical scale.
The reason being that I can grab that position knob and move it up and down if I want so I had to go back and zero it out.
And thanks for pointing out it was still on DC setting xP that's why I try to include the knobs whenever I take a pic of something on the scope :grr
Maybe a better way to explain is if I understand this...
Before signal was applied there should have been two straight horizontal lines on the scope
One at about 1.6v DC (channel one probe at emitter)
One at about 9.8v DC (channel two probe at collector)
So that's what I meant that they had to be reading correctly so I had to put them at zero when connected to ground.
xP
Ok also thought of something
Say I want to measure the voltage of my car battery with my oscilloscope :loco :lmao:
Since I am able to move the horizontal DC line up and down with a knob I need to zero it before taking the measurement
Right ?
Zero is wherever you want it to be. :)
The center line is just that, the center. Put the coupling switch on 'gnd' and move the line to wherever you want to use as zero reference.
If I want to measure DC, I will use the center as reference if I do not know the polarity. But if I know it's positive DC, I will use the bottom grid line, whereas if I know it's negative DC, I will use the top grid line as my zero reference.
If you forget what you had set the reference to be, just put the coupling switch back to 'gnd' again.