Electronics > Projects, Designs, and Technical Stuff
Phase Shift Oscillator Question - UPDATE: Circuit is a ring oscillator
<< < (3/4) > >>
orolo:
This is not a phase shift oscillator. It's more like the classic LED chaser circut, a ring of switches that trigger each other. When Q4 is saturated, Q6 must be off to keep Q4's base high. Since Q4 is saturated, its collector is low, which will turn Q5 off. As Q5 turns off, its collector goes up, which then turns Q6 on. As Q6 turns on and goes into saturation, Q4 is turning off.

So the thing goes:   

Q4(sat), Q5(turn off), Q6(turn on) -> Q4(turn off) Q5(turn on) Q6(sat) -> Q4(turn on) Q5(sat) Q6(turn off) -> Q4(sat) Q5(turn off) Q6(turn on) -> etc.

If your circuit is symmetric, you should see identical waveforms in the transistor collectors, 120 degrees out of phase.
spec:

--- Quote from: orolo on November 24, 2018, 01:29:31 pm ---This is not a phase shift oscillator. It's more like the classic LED chaser circut, a ring of switches that trigger each other. When Q4 is saturated, Q6 must be off to keep Q4's base high. Since Q4 is saturated, its collector is low, which will turn Q5 off. As Q5 turns off, its collector goes up, which then turns Q6 on. As Q6 turns on and goes into saturation, Q4 is turning off.

So the thing goes:   

Q4(sat), Q5(turn off), Q6(turn on) -> Q4(turn off) Q5(turn on) Q6(sat) -> Q4(turn on) Q5(sat) Q6(turn off) -> Q4(sat) Q5(turn off) Q6(turn on) -> etc.

If your circuit is symmetric, you should see identical waveforms in the transistor collectors, 120 degrees out of phase.

--- End quote ---
Wow!
spec:
 @ ANTALIFE

What frequency is the circuit actually oscillating at? I can't make out the legend on the scope screen. Also what supply voltage does the circuit have.

My back of cigarette packet calculation shows around 500Hz.
Zero999:

--- Quote from: orolo on November 24, 2018, 01:29:31 pm ---This is not a phase shift oscillator. It's more like the classic LED chaser circut, a ring of switches that trigger each other. When Q4 is saturated, Q6 must be off to keep Q4's base high. Since Q4 is saturated, its collector is low, which will turn Q5 off. As Q5 turns off, its collector goes up, which then turns Q6 on. As Q6 turns on and goes into saturation, Q4 is turning off.

So the thing goes:   

Q4(sat), Q5(turn off), Q6(turn on) -> Q4(turn off) Q5(turn on) Q6(sat) -> Q4(turn on) Q5(sat) Q6(turn off) -> Q4(sat) Q5(turn off) Q6(turn on) -> etc.

If your circuit is symmetric, you should see identical waveforms in the transistor collectors, 120 degrees out of phase.

--- End quote ---
Yes, it's a ring oscillator.
ANTALIFE:

--- Quote from: spec on November 24, 2018, 05:50:03 pm --- @ ANTALIFE

What frequency is the circuit actually oscillating at? I can't make out the legend on the scope screen. Also what supply voltage does the circuit have.

My back of cigarette packet calculation shows around 500Hz.

--- End quote ---

Circuit oscillates at 59mHz (yup milli) also supply voltage is 4V
Navigation
Message Index
Next page
Previous page
There was an error while thanking
Thanking...

Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod