#1807

Рет қаралды 6,072

Күн бұрын

Episode 1807 circuit of the day
another oscillator circuit using a twin T notch in the feedback
I had already recorded this video, then Alan released his video first: • #380: Circuit Fun: Twi...
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Пікірлер: 38

@MinceWalsh 17 күн бұрын

In 1972, I built a three channel color organ using 4 op amps and this exact circuit. Mind you, the op amps were industry samples given to me by a distributor. I was 14-15. I designed it using the above filter from the Burr Brown op amp handbook. Worked decently. later, received a price list of these one inch by two inch epoxy rectangle op amps and found I had built a color organ with around a thousand dollars worth of laboratory grade op amps. I had mixed feelings about that.

@paullongley9650 6 ай бұрын

This notch/bandpass plot twist was a revelation - thanks!

@cmuller1441 6 ай бұрын

4:50 I was about to say it's a notch filter... 😂😂😂

@indigoskywalker 6 ай бұрын

i thought the same, low pass and high pass in parallel is a notch, in series is a band pass

@davidv1289 6 ай бұрын

Wow, what are the odds of two twin tee notch filter videos released on the same day? Free Electron did one on using twin tee notch filters to analyze distortion. Great video, thank you . Regards, David

@RedbeardtheEngineer 6 ай бұрын

Educational and entertaining what more could you want.

@rfburns5601 6 ай бұрын

Good Circuit. Good concise explanation. Thanks. Ize beez luvs me some circuit o' the day!

@chrisharper2658 6 ай бұрын

You didn't cover the positive feedback loop. It wouldn't work without it and too much would probably cause you to loose the pretty sinewave.

@tommiller1315 6 ай бұрын

Thank you for providing instruction and entertainment together. Also, this is a pleasant brain exercise. Great circuit, and explanation. Provides more insight into the gyrator operation (for me at least) when the circuits are compared. Now this makes me want to see "Tone Control" and "AGC" circuits explained in a way I can understand too.

@byronwatkins2565 6 ай бұрын

Equally important, the phase change around the feedback loop must be 2n pi radians to get positive feedback. This happens for both T's only at the right frequency.

@david4368 6 ай бұрын

Nice presentation. Looking forward to more. Thanks!

@rhiantaylor3446 6 ай бұрын

Understand how it oscillates at the set frequency but can't see why it doesn't run to the rails and give a square wave output. Think I recall a thermistor or even a small bulb being used to limit gain so the cct only just oscillates and avoids the harmonics that would ruin the clean sine wave.

@KeritechElectronics 6 ай бұрын

Pretty interesting :) Positive and negative feedback combined to work together!

@gordselectronicshobby3853 6 ай бұрын

I think the filter is a Twin T Notch Filter...

@AnalogDude_ 6 ай бұрын

I have vc hi pass filter coupling this to vc low pass filter creates really awesome noises, noises you might not expect. Cool circuit this T-bridge.

@tvelektron 6 ай бұрын

Would be so interesting to compare it with the phase shift oscillator, almost the same component requirements / number.

@mathic5599 6 ай бұрын

Interesting! Twin T is a notch filter, definitely not a bandpass! It oscillates because only at the notch frequency, the phase shift crosses zero very sharply, going from +pi to -pi. Since your gain is very large (A=111) and the notch is not perfect, your overall loop-gain AB probably becomes nearly 1 and the phase shift AB is 0 degrees only at the notch frequency. For oscillations, overall loop-gain AB should be 1 angle 0 degrees, as in Wien bridge and other oscillators that use a bandpass filter in the feedback path.

@bobdoritique7347 6 ай бұрын

Merci for this video.

@ajingolk7716 4 ай бұрын

Nice video as usual 🤷🏻‍♂️ does types of capacitors and resistors makes a difference?

@indigoskywalker 6 ай бұрын

@IMSAI Guy, glad you are doing synth stuff

@AlessandroAllegretti 6 ай бұрын

It would be very interesting to find a way to control this fine sine wave oscillator with voltage, like a VCO

@andymouse 6 ай бұрын

WOW ! if you put two pots in there at the 'T junction' of both filters you have a Baxandall Tone control set up. Exactly what I'm playing with but having a hard time working out how it functions, this is quite a big shove for me !! I'm not sure how to pick a value for the pots, because in an example circuit I have they give no explanation of why the values are what they are and they dont say whether they are LOG or LIN ? I think LIN but who knows, maybe I can think from another angle....cheers !!

@michaellundsrensen2292 6 ай бұрын

Can you tell me how much distortion there is on that sine signal? With a four-fold potentiometer and replaceable capacitors, it can become a nice little sine generator! But the distortion must be low.

@IMSAIGuy 6 ай бұрын

watch the video I link in the description.

@robinbrowne5419 6 ай бұрын

I often see weird and wondrous circuits in the thumbnail. I am sure I am not alone when I say "Holy cow. How does that work? I better watch the video and find out." So in other words, these thumbnails are a kind of click bait. Lol. PS - Ohh.. now I sort of get it. A high pass filter and a low pass filter combined. It does make a nice sine wave 👍

@tedivester4947 6 ай бұрын

Well that just doesn't seem right. Don't know why, but it doesn't matter. It's a sunny warm day here in the north country and the wife just told me to get away from the computer and do some much needed yard work after the long snowy winter. Sigh!