Making a FET Phase Light -- The Learning Circuit 32

First, if you did 10 more videos of various transistor/amplifier circuits with such brain teasers, it would be awesome.  What's cool about this is that the cause and effects can be opposite what "common sense" (aka hindsight bias) would dictate when you see lights turn on and off - which is why many just think of electronics as magic.

Below is my take on what's happening.  I definitely need some help and validation from analog experienced folks as I just recently began learning transistors and essentially don't know what I'm talking about.

Since the draining and charging are happening in parallel with threshold voltages required to overcome for the MOSFETs to do anything, I can't begin to describe it clearly.  But here goes...

• 1:39:  Versus the perspective that the voltage comes from the ground, I look at this as the ground is the zero reference.  I would say that voltage is variable at nodes on the positive side based on capacitors charging and discharging.
• When first switched on, all three capacitors should charge at the same rate since they are all sourced from the same voltage and flow through the same resistance (1.33ohms) on their own paths to the capacitor of their stage.  The current isn't sufficient to light any LEDs during this phase or perhaps just a quick blink.
• Once the capacitors charge to the MOSFETs' threshold voltage, they first go through their triode mode acting as a variable resistor.  Triode mode makes the MOSFETs and their drain resistors act like a variable voltage divider that now works on the capacitor of the next stage.  This is where the separation occurs in timing to create the shifting effect.

• By the time the MOSFET of a prior stage goes to saturation, the capacitor of the next stage would be pulled down.  This would fade out its LED as the MOSFET gate voltage lowers with this discharging capacitor. 
• When that MOSFET is completely closed, the capacitor of the next stage is full on charging again which will eventually surpass the MOSFET threshold voltage again.  Rinse and repeat down the line. 
• Because the capacitors charge/discharge visibly "slowly" and there are voltage thresholds for the MOSFET to crack open, the choice of 2.2uF capacitors with the MOSFET voltage threshold allow for a shifting effect.

I welcome someone correcting my perspective as I feel I'm on the brink of understanding.  Please do!

Karen, I've never scrubbed a time line so much.  You might  have 1 view from me, but with 100 minutes watch time.

See ya',

Sean

Re the scrubbing timeline comment: Hehehehehe. That's so good to hear.

You're explanation sounds correct! Thanks for taking the time to write that all out.
I'd love to do more project videos based on this concept. Right now, I'm still moving along, one concept/component at a time, so I don't do much revisiting. Since I like to follow each concept/lesson video with an applicable project, I don't have much time in between to come up with projects for previous concepts. For those not aware, I do all of the research, writing, prototyping, and planning for my episodes and do about one/week so I'm on a pretty tight schedule without much room for extra, fun project experimentation.

If you have circuits or projects you think would be good for TLC, I'd be happy to hear about them. I'm sure we could plug in some extra projects here and there. It's always good to revisit and review concepts you learned awhile ago. Keeps the information fresh and makes it stick better.

Thanks for the feedback, Sean!

Re the scrubbing timeline comment: Hehehehehe. That's so good to hear.

You're explanation sounds correct! Thanks for taking the time to write that all out.
I'd love to do more project videos based on this concept. Right now, I'm still moving along, one concept/component at a time, so I don't do much revisiting. Since I like to follow each concept/lesson video with an applicable project, I don't have much time in between to come up with projects for previous concepts. For those not aware, I do all of the research, writing, prototyping, and planning for my episodes and do about one/week so I'm on a pretty tight schedule without much room for extra, fun project experimentation.

If you have circuits or projects you think would be good for TLC, I'd be happy to hear about them. I'm sure we could plug in some extra projects here and there. It's always good to revisit and review concepts you learned awhile ago. Keeps the information fresh and makes it stick better.

Thanks for the feedback, Sean!