How Colpitts Oscillators Work - DC To Daylight
Вставка
- Опубліковано 25 лип 2024
- In this theory-based episode, we look at what it takes to make a Colpitts oscillator produce a sine wave. We cover Barkhausen’s criteria in order to keep the oscillation going, a basic NPN transistor amplifier which controls the gain, and calculating the resonance of the LC circuit’s feedback network. Though there are better options for a more spectrally pure and accurate sine wave, the common-emitter BJT Colpitts makes for a good building block and starting point when learning about oscillators bit.ly/39qj1ca
Engage with the element14 presents team on the element14 Community - suggest builds, find project files and behind the scenes video: bit.ly/3tmdewv
Visit the element14 Community for more great activities and free hardware: bit.ly/3q6YMpu
Tech Spotlights: bit.ly/3qPrDhM
RoadTest and Reviews: bit.ly/3pV5Bux
Project14: bit.ly/31wbnJY
#0:00 Welcome to DC to Daylight
#1:22 Oscillators
#2:31 Schematic
#6:28 Breadboard
#13:16 Give Your Feedback
#oscillators #colpittsoscillators #transistors #NPNtransistor #sinewave - Наука та технологія
A really good video. The explanations with the calculations raise the game. Very helpful. Thank you
Thanks, much appreciated! -Derek
I agree. I'm doing math as a hobby. I love it
Derek, thanks for another great video. You're correct. Having someone demo and drag me through all of the calculations has emboldened me to give it a go. Thanks dude!
Absolutely. Hope it works out!
What a great video! I'm looking forward to more!
Fantastic video, sir. I seem to have all the components on hand to build and measure this circuit, I believe I will be trying this later!
Thanks for using the tiny connecting wires on the breadboard: makes everything so much easier to see.
Thanks. I usually lay things out with presentation following functionality. However, since I started using the overhead camera/breadboard, I'm trying to lay things out so it's easier for folks to replicate. Thanks for the feedback! -Derek
Excellent video,. Great presentation, nice job!
That background text later the left had me laughed for a second. Perhaps it is my first time on the channel and it is a good way to show off without trying. Haha 🙌
Thanks for another great video! You explained it very well.
Thanks James. -Derek
Excellent tutorial
Fantastic explanation! This really helped me.
Great lesson. Thanks.
Awesome video !
Good presentation, thank you!
Anytime! -Derek
I love this video, thank you !
thank you for sharing .
Very nicely explained component by component.
Great start. Using the same baseline circuit more exploration is desirable. Loop gain can perhaps be tested by perturbing the oscillator. What sets the amplitude is worth discussing. Temperature tolerance/drift is another aspect, even with crystals. Since oscillator output is used as reference signal, its clock jitter, noise are worth discussing.
I enjoyed that video thank you my friend,.
The first and the only explanation I've understood
Great introduction to the key factors. I noticed your scope channel 1 was at 1x and channel 2 was as 10x. Was this intentional? Wouldn't the 1x probe further load down the tank circuit?
Justin, you are correct.. when I was shooting I didn't realize I left the probe at 1x. Doh! This is a good point, which I should have noted in the video - 1x which is useful for low frequency probing (and those that can withstand moderate loading ), should not have been used for this measurement. 10x is better for higher frequency measurements, and presents a much lighter resistive load, as well as a lower value of capacitance which could cause frequency shift. As DefPom pointed out in another comment, a simple inductive pickup coil could be fashioned from wire and used to sample the frequency - but note that mutual inductance can also load down the circuit. Nothing is simple is it?! -Derek
Good explanation! Thanks!
Thanks Michael! -Derek
Amazing
Being off by 10 kHz from 77kHz is totally justifiable by the component's tolerance. Caps and Inductors in those ranges have solid 10% tolerance, and their errors combined can easily cause this ~15% jump in f0. The frequency does not seem high enough for the pF-range capacitances in the breadboard to influence that much.
Cheers and thanks for the great video
Great stuff. Teeny little error: the 3rd resistance in the overlay text at 12:30 should read r'e*β, not RE*β (i.e. R1 || R2 || r'e*β). This is for the same reason that the emitter-bypass changes the (open loop) gain of the common emitter to Rc/r'e from Rc/Re.
Thank you sir
Thank you.
Question : why can we consider that the 2 capacitors are in series even if there is a connection at the base between
Wow...Thanks!!!!
that was cool. building a test jig out of veroboard with everything super close would be better ehh. use sockets for the different components?
Good luck and God the Almighty blessed you with eemaan and Divine happiness,thanks for educating us.
I'm having a hard time with being able to classify oscillators. I do understand how this one works, but occasionally I'll run across a topology in an antique radio that I fail to understand. Namely, when I find that the tank circuit is in a parallel configuration. My understanding is that with phasor analysis, at its resonant frequency the impedance of a parallel LC combination would approach infinity. Thus I would imagine that no current at the desired frequency should flow through the oscillator tube that should be providing feedback
I built this circuit a few years ago. The transitor is going in and out of saturation so you are getting a lot of distortion from that. notice that the output of the LC is very clean sign wave. I ended up amplifying the signal at the tank. It was way better distortion.
This makes sense. Great work!
Great basic tutorial! Bookmarking this to rewatch next time I start building an oscillator.
Isn't base voltage at the emitter only equal to VBE -0.7 when the voltage divider bias is stiff? Otherwise you need to solve Base Emitter Loop for base current and use beta values to calculate current? It works fine in this particular example because the resistor values are handpicked to avoid this calculation
the output is distorted because you have set the gain with respect to re(which is a function of Ic)
there is another form of bypassing where two resistors are used and one of them is bypassed with a capacitor
Attaching the scope probes to the oscillator directly would have affected the oscillator frequency, the best way is to use a near field probe or if that’s not possible couple in through a 1pF ceramic cap.
Good tip. Thanks Defpom.
I think it would have brought the frequency down, but in the video we see that the frequency is higher than expected. So it must be something else.
Hello everyone
I want to make a little project so I can wirelessly (just a few centimeters) power an LED strip (just a short section) using a transmitter and reciever coil.
I have a 6V 4Ah lead acid battery. I want to use this as the input. I want to convert this to an AC signal around 100kHz and connect the transmitter coil to it.
On the other side I will have the reciever coil that goed to a rectifier and then to the LED strip (5V 1.9W).
What is the best (and most simple) way to do this? I was thinking about using a Colpitts Oscillator. Can this work?
Also is the battery ok or should I just start with a 12V voltage from a bench psu to make my life easier?
Part 2 video is there on this topic
When you started the video and said a little bit about math i taught you are going to include the calculation regarding amplitude of oscillation...so say something about amplitude of the oscillator
Why should how do u consider those resistors values? Could you explain me the reason for particular values.
this is a wonderful Saturday afternoon cup of coffee video ☕ 🍩 would something like LTspice free stuff simulate this circuit, then PCB software to have some made? 😎 thanks a lot
How did you calculated the value for C5?
A rule I generally follow is to make the Xc = 1/10th the value of Re at the upper desired frequency. So if desired Xc ~= 120 Ohms, C = 1 / (2pi * f * Xc) ~= 1.3uF. I grabbed what I had on the bench... 1uF. in reality, it would probably be better to use 10uF, and keep Xc fairly low for the design frequency of 1kHz. -Derek
The oscillator operates at 77 KHz, but the amplitude regulation path has roughly 1.5KΩ and 1μF and thus approx. 100Hz loop bandwidth. Can that be the reason for the distortion.
Would you not be better off using a real inductor in your circuit as opposed to relying on a side effect of a resistor?
when Q1 and R4 is not there, then you will have 1.86V over R2.
But as soon as you put Q1 and R4 in parallel with R2. The total overall resistance below R1 changes, it becomes less.
That means you will not have 1.86V as Vb.
The circuit would be a little better if you put the 1 K collector resistor to the gnd side of the tank. Remove the 2uf cap and connect top of the tank with a wire and place that cap on bottom of the tank to gnd, and if course remove direct gnd from the bottom of the tank.
선생님 전 선생님 무시하는 말이 아니니 그저 선생님 의견이 보편저 전기 전자 킷트의 확대에. 도움 되라는 말합니다.저는 기본의 전기전자는 제 남동새 어깨너머 배웠지요, 그래서 모르는 부분이 더 많으나 고등학교에서 기본의 전기전자는 다 배우더라고요 그래서 거기에 약간의 선생님의 조언과 부연 설명 매우도움 됩니다,그러나 창작자는 자기의 새로움 더 추구함 그게 더욱 진화입니다. THANK YOU.
Barkhausen says that the loop gain must be equal to 1, and not greater than 1.
I know you are from the past. From which year are you from. How much you paid for the flux capacitor?
The base voltage calculation could not be simply derived with voltage divider since R2 is in parallel with RE thru the base. Hence Thevenin's is needed to analyze this.
It’s still a good approximation tho. As long as the current going into the base is significantly smaller than the current through R1; then just neglect the base current and assume R1 and R2 are in series.
For DC at least, given that the impedance looking into the base is beta times RE, and RE is relatively large... it is fine in this case. Yes, Thevenin works for all cases, but rather than muddy the waters for newcomers, I've left him out of this example deliberately. -Derek
I am 100% - you
With an opamp is better
Why not element 14 ship and accept orders from Pakistan
I want to oscilloscope, I don't have one.
There are some cheap chinese models.
@@JohnUsp I am from Algeria, and the prices of the cathode oscilloscope device in Algeria are approximately astronomical 11,000 Algerian dinars, and Algeria is a consumer country, not a producer, such as America, Canada, Japan, China, South Korea, Europe and others. I studied industrial electronics, I graduated in 2019 and to this day I do not have a cathode oscilloscope. Poor countries like Algeria have to suffer a lot to get simple things, even if used. Now second-hand products are coming from Europe, it is likely that their owners have abandoned them and are sold at astronomical prices while they are used. Few times you will find things that you might say are affordable and yet still be expensive. The minimum monthly salary for an employee in Algeria is $90 per month. The average salary we have in Algeria is between $200/300 per month. Poverty is very high in Algeria.
@@user-kr9kq3fo4v You can do a simple oscillocope using your Cellphone. I guess works well up to 100kHz
or using your PC/Laptop, search for: "diy oscilloscope"
@@JohnUsp To be honest, this is the first time I've heard of this information. I will try it out. Also my mobile phone is not very good Samsung A7 2017, and the computer is much weaker AMD E1, from 2015. I have another computer, very old Pentium from 2009. And I hope that the connecting wires and other requirements are not expensive. The United States of America is wide open in terms of electronics, design and development. I wish I learned a considerable period in the United States of America. Albeit short term, especially the basics.
looking at the flux capacitor in the back, I guess this means that you were near the railway when the Delorean got wrecked.
You are correct! Ended up with a nice souvenir however.
DC to daylight? I don't think so.
Can you clarify?
@@AmRadPodcast oscillators cannot go down to dc by definition
@@brothertheo2677 I suppose the title could be misleading if you are unfamiliar... The show, or segment is called DC to Daylight - I cover subjects that span the range of DC, to optical stuff.
@@AmRadPodcast Ah, Assumed it was clickbait. My bad.
@@brothertheo2677 no worries. I checked out your channel. Pretty cool stuff!
excellent×