Colpitts Crystal Oscillator
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- เผยแพร่เมื่อ 2 ต.ค. 2024
- Colpitts Crystal Oscillator
We have made a few oscillators in past videos, but this is the first one that makes use of a crystal. The Colpitts Crystal Oscillator circuit is found in a majority of modern electronics that require a precise clock signal.
Invented in 1918 by Edwin Colpitts, this circuit uses a voltage divider consisting of two capacitors and a pair of bias resistors.
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Please watch: "Diodes: The basic building block of all digital circuits"
• Diodes: The basic buil...
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Thanks for taking the time to make these videos. They are very helpful and interesting.
Paul I've used one of these for Years I use a 10.7 MHz crystal, and have used it for checking out I.F. stages on FM, lovely very stable circuit , every hobbyist should have.
Paul de M0BSW
Thank you
Using a package of CMOS gates such as the 74HCU04 is a nice alternative. use one gate for the oscillator and one gate for a buffer, leaves 4 more gates for whatever. Only requires 1-74HCU04, one 2.2 M resistor, 2 caps and a crystal, with rail to rail swing at very low cost
Great video, but as someone who is trying to learn the design of these oscillators so that I can build one for my desired frequency, it would be helpful if you could include or maybe just add to the description or maybe just add a link to an external doc containing the formulae that relate the various component values to the resonant frequency of the circuit. I am trying to make a 13.56MHz oscillator but I am not sure how to adjust the circuit you have shown for that purpose. Also, slight tangent, but do you have a video that teaches how to find the internal resistance of a given oscillator/signal generator? I am working on a rather niche antenna design for this frequency and I need rather good coupling and as much power transfer as I can get as it will be a fairly powerful antenna and losses from poor impedance matching may be detrimental.
Max, it's been a year since your post, so hope you have succeeded in your design. I used to build circuits and antennas for RFID, operating at 13.56MHz. At that time I used a digital SWR meter from MFJ. It could also measure the complex impedance of circuits, a nice feature you wanna have to make it easier to tune the system to resonance, minimizing reflection, etc. I highly recommend it. Regardng the oscillators, I used to start mine with the 13.56MHz crystal itself. If you are interested in the formulae, my reference for that is Boylestad & Nashelsky, Electronic Devices & Circuit Theory. Good luck!
Getting into building synthesizers and I'm seeing a lot of this stuff for the first time. Very fascinating work. Thanks for making this!
You are a great teacher, calm and smooth. Thank you sir, and if it applies as to the patch I've seen in a few of you videos, Thank you for your service.
They are very helpful and interesting.
I still don't quite understand how the crystal is able to cause the rest of the circuit to resonate?
Does the current draw accross the crystal change depending on the flex of the crystal, like an inductor has a reluctancy to change current?
I'm assuming that perhaps the crystal draws a larger current while flexing, and then once saturated the current draw drops off, causing an increase in voltage?
I'm just struggling to understand how the rest of the circuit _reads_ what the crystal is doing...
Hello. Nice video but of course, it didn't work if you do exactly the same as shown... No one oscillation after trying others quartz, frequencies, condensators, transistors... more then one time tried, on the same board and onthe air, with the same wires and the same components... Voltages are correct, trnasistor is functional, but this oscillator didn't work. Sorry but why ????????
you did not mention the value of the crystal, as well as the basic of its work, or even how to calculate the frequency
> the basic of its work
That part is easy. A crystal (properly speaking, a piezoelectric resonator - both crystal and ceramic resonators work the same way) is a special kind of capacitor. Normally a capacitor passes alternating current and blocks direct current. A resonator also blocks certain resonant frequencies.
If you want more math, it's very similar to a resonant tank circuit. The graph of susceptance-vs-frequency crosses zero at resonant frequencies. *You'd choose the frequency by choosing a suitable resonator* - and you can fine-tune it with a capacitor in parallel, often an adjustable one. (A parallel component adds susceptance to the circuit, which allows you to adjust where the total susceptance crosses zero.)
So at the resonant frequency, the susceptance of the capacitor-pair cancels the susceptance of the resonator. Let's call the susceptance of both capacitors B. The susceptance of the resonator is -B because they cancel. The susceptance of each capacitor is 2B because susceptance works like conductivity.
Now here's the interesting part. The transistor will inject alternating current (small-signal model) at the emitter. I'll assume the base current is small, and so is the current that's passed to the next stage. So the injected current divides into three paths. Some amount goes through the emitter resistor, some through the lower capacitor to ground, some through the upper capacitor. The upper capacitor current is then divided again, some is lost through the bias resistors, some is conducted through the resonator.
The emitter-resistor current is lost. That resistor value is going to determine the transistor gain, so I'll assume enough current remains to allow the oscillator to function. Similarly, the loss through the voltage-divider resistors can be neglected for a first estimate of how the circuit works. What is the susceptance of the upper capacitor and the resonator? It's a parallel-sum: 2B||-B = B * (2||-1) = B * (-2/(2-1) = -2B. That's exactly opposite the 2B through the lower capacitor.
This zero-susceptance result is a singularity - trying to use it causes division-by-zero problems. The voltage divider formula doesn't have that problem - we can expect the resonator to resonate at twice the output voltage. Current loss will cause some current to flow through the upper-capacitor/resonator loop, and the voltage-divider formula can be applied. That loop has total impedance j/B - j/(2B) = j/B * (1 - 1/2) = j/(2B). So the voltage applied to the resonator is j/B / (j/2B) = 2 ---- twice the output voltage.
This means that the output signal has no difficulty stepping up to the higher voltage that's driving the resonator. (Resonance is weird that way.) But if the transistor injects current at a slightly different frequency, it doesn't get the same step-up effect. Non-resonant frequencies are damped out, the resonant frequency (or frequencies) grow until they are limited by parasitic losses.
If the self-sustaining oscillation is able to grow too large, it will cause distortion and chaos. Oscillator stability depends on having a small but sufficient amount of loss, just enough to balance gain at the operating signal level. And resonator crystal limits other frequencies to much lower levels, rejecting noise and non-harmonic distortion. It can also improve stability.
@@jordanrodrigues8265 Just wanted you to know, this comment was fascinating. It's always a bit of a bummer when you put together a nice comment like this, it gets overlooked. That said, the reward is mostly in sharing knowledge. Communication really helps me gather my thoughts, and understand what I actually know vs what I "kind of" know.
When all is said and done, who really cares? Sometimes you just gotta nerd out :)
@@jordanrodrigues8265but what is the value of the crystal
Hi from Galicia (Spain)!!!I have seen your video of the Colpitts oscillator and was wondering how to make it sound? I have got into my head to make a musical osc with those quartz crystals, but I don't know how to start ... Any recommendation or scheme would be of great help ... I have several CD4060 ic's, if they were of any use ... Greetings 👍💖👋
Is the crystal natural or synthetic? Cool stuff! 1918 wow
Thanks. I wired this schematic on a breadboard and it works for me on the 40 meter band.
Next I'll substitute a tuned circuit VFO for the crystal.
Thanks for posting. Question Crystal oscillator at a frequency of 32.768 KHz how do I calculate capacitor load values? Of course the circuit is the same as you used in this video?
only 704mv, I think you need to swap around your C1 and C2 caps to get more gain
I'm pretty sure you meant R1 and R2, as C1 and C2 aren't actually configured to divide anything.
At any rate, R1 and R2 are every bit as equal as C1 and C2, soooo...
will be good to use the MATH or FFT mode in the scope to check the oscillator "purity" looking at the spectrum of it
The Colpitts oscillator is not very pure. 0.1% THD is, probably, the most one can get from it
Hi It is possible to make Pk Pk voltage = 5V ? without adding extra Transistor ?
Hi. I built this circuit. I only had 22k resistors. I tried 22k instead of 33k. I also tried 470pf instead of 220pf. the circuit did not work.. I saw a flat dc voltage on the oscilloscope, what is the reason?
You mean capacitors right? Make sure you used capacitors, and if you did, try adjusting the resistor values. Crystals are very temperamental to achieve oscillation. Also, if you didn’t use a 27mHz crystal then you’ll need to adjust the values of both the capacitors and resistors. You can probably look up the data sheets of your crystal or search for example schematics using that frequency crystal. I hope that helps. Cheers!
@@hrvstmusic I installed the same circuit. maxed 14 mhz crystal worked
I don't remember the Colpitts originally having the Xtal, is this a modified one?, remember this one and the Hartley back in the day.
Anyone know of a Voltage controlled version?, also if we want to go down to say 50Hz, how do we do that with an Xtal?
I like your video but you shouldn't be doing it for sponsors and money. Do it cause you like sharing your ideas with people. Sponsors and money is what screws everything up, because then it becomes about fame, and how do we play with circuitry together when you have 40,000 views and subscribers. That's called playing with yourself and letting people watch!
Could you just stick an aereal on the output and flip the power on and off to send a morse code radio message?
please say what is the value of crystal??
I'm a total noob, but to share what I've already picked up about oscillators...
You would adjust the frequency by changing the value of the capacitors.
Larger capacitors would lower the frequency, smaller would increase frequency.
For a demonstration of this, take a look at something like a feedback oscillator.
Basically a joule thief with a frequency regulated by the value of capacitor as opposed to the value of resistor.
Also, at a low voltage (5 volts) you can decide the value of the components for yourself.
The relationship to other components being obvious...
The two 33k resistors act as a voltage divider, the two capacitors also act as a voltage divider.
If they aren't equal, you get the ratio of the voltage you divided.
While there doesn't seem to be any upside to dividing the voltage via the capacitors in this circuit, lowering the voltage by using one higher (or lower) value resistor than 33k would change the frequency of oscillator via varying the speed of the capacitors charging.
Simple stuff guys, just look at what you can build with the individual components as they sit in that circuit.
i have used a 30MHz crystal instead of 27MHz, but there is no output. What may be the problem?
How did Colpitts do it before the transitor was invented?
probably a vacuum tube, could be wrong though.
The output frequency is a CB radio frequency. Therefore I will give this video a big 10-4 !
Its has no modulation. So there is a LOT more circuitry your going to need to get this to work on CB. Its just an oscillator, not an RF Transmitter. It has no modulation and does not output RF.
Can I use one of this variabile capacitor used in radio to change the frequency? I Need a 333khz oscillator.
In which equipments this oscillators are used
I've tried constructing this and i am testing different crystal I have on hand. I bought some awhile back and havent test, or didn't know how to test them. I am seeing the signal but it looks pretty crappy. They're looking more triangle like. Exact values as you have... Wonder if the crystals I have are crappy or if I need to build a different circuit to test these crystals..Any input greatly appreciated. Thanks. Interesting channel
The crystals only have an impact on the frequency, not the quality of the waveform. I would check the circuit for loose or poor connections or something that may be generating noise.
learnelectronics after some research, I didn't take into account impedances or the state or reaction of the BJT
learnelectronics can we increase frequency of a circuit used crystal?
works perfectly , I use 4 MHz crystal . I need this oscillator for my vacuum tube am transmitter ,thx
+ELECTRONICS thank you for watching and commenting. I'm glad you liked it.
The video does not explain how such oscillator works, nothing about the electron flow.
I think you've got that transistor in backwards, buddy...
Do you have any videos on how to build a Rife frequency oscillator?
Can you name this circuit it's testing crystal quartz?
Colpitts Oscillator
In your diagram you have two capacitors, I see only one on the bread board.
Cricket 40 uses this scheme
Thanks for this gr8 video. Is it also possible to make a variable frequency oscillator using the same crystal oscillator?
You can try frequency divider ICs like CD4060 or use Flip-Flop circuits
I have a raw quartz crystal. Can I make its oscillator too?
Im currently trying to measure inductors, since I don have all the lab complete, one way to measure them is to use a very fast signal, I willy try to build this to test them out. Thanks mate!
How did you calculate the components values
Threw together a Ball park version...it Worked...lol
can you help me design a a 7.77MHz oscillator???
Hi...just replace 7.77mhz crystal
How to check kilohertz crystal
(Any one )What the purpose of this device where is it used and for what reason
Crystal oscillators are used to provide clock signals for microprocessors and microcontrollers that don't have internal oscillators. It's what allows the CPU to change state millions of times per second.
Crystal resonators are used for adjusting clock signals in microcontrollers. Also they are commonly used for making oscillators
They are less often used in radio transmission. You can usually see them in wireless data transmission modules like that you use with arduino.
Great video. Works . How would I modify this oscillator to drive a 74LS14 Schmitt Trigger? Thanks.
Try adding a BJT negative-feedback buffer (or multiple): tinyurl.com/y5ovvjk2 (simulate on max speed until the timestamp in the bottom right is around 350us - the oscillator takes a while to increase the amplitude.)
Don't make the coupling capacitors too big (15pF or less) - I tried 30pF but it caused previous stages to collapse owing to the bigger capacitors' relatively low impedance. You can also try increasing the feedback resistors for more amplification.
Hopefully, that lets it fit the high/low thresholds of the 74LS14. Good luck with your project :)
you didnt bother to trell us the crystal details
Is itnuse in fm transmitter and receiver??
How it works
thank you for the video.can you tell me whether i can change the peak-to-peak voltage or not?
How do i connect a transformer on the circuit
How do i get 30 mhz instead 0f 26
What is the value of the crystal please?
can we use it with a piezo element to turn water to vapour to control humidity?
Can a square wave be generated from a crystal? What kind of circuit would I need?
Jon Lorusso a Schmidtt trigger would do the trick
Thanks For Video
How i can test crystal is working or not. Of course with an oscilloscope, when power is on cirquit, but is there other methods?
You can use a multimeter which can also measure ranges in MHz. They display the frequency and duty cycles. They are affordable for a good price, but don't cheap out on some shoddy knock-off brands.
Where would I inject an audio signal into the oscillator for a low power transmitter?
My question too ! What was the value of the crystal ??
27 MHz or nearest.
How do I do this for a circuit that has to be in a humid environment? I want to switch over to crystal oscillators from capacitance-based timing precisely because humidity affects capacitor values. So I'm trying to get away from anything that has capacitors in it. Any way to do it with inductors or something? Or maybe just the crystal with darlingtons or mosfets or other reactive components? Thank you in advance!
The problem is these circuits work perfectly well when placed on breadboard when i solder the same circuit on a perfboard i dont know what happens the output just disappears. I didnt fry the transistor and i also checked my connections many times i dont know what happened. Please someone help me
How can we multiply the output frequency to use this oscilator in radiotransmiter? (like 100 MHz FM)
hi...how we can produce 100mhz frequence with quartz cristal?
how this circuit work?
i road some were that i can make an fm reciver circuit with the colpitts oscillator . so how can i turn this oscillator in the simplest way to an fm radio ?
thank you so much for these great videos :) .
Try adding a resistor between 1k and 10k from 5V to the oscillator, then putting a 22nF decoupling capacitor from the ground to what used to connect to 5V (ie, the collector). If the frequency of the FM signal is greater or less than the resonance frequency, the oscillator will conduct less, and the voltage at the collector will be higher. If there's not much of an audio signal on the FM station, then the frequency received will be closer to the resonance frequency. Thus the oscillator will conduct more, and pull the collector to a lower voltage. This way, the FM is demodulated.
You can couple the oscillator to one or more NPN negative-feedback buffers to increase the output signal, as shown here: tinyurl.com/yxpohc2k
- Use smaller coupling capacitors, between 1nF and 10nF, as larger ones can
- The amplification is positively correlated with the value of the feedback resistor (in my case 1M)
^^ I got that amplifier design from talkingelectronics.com
I'm not sure if that will work because I've never tried such a circuit to make a radio that receives audio (I've only made one that receives digital signals) but you can give it a shot.
I do the simulation using multisim but It did not work please help me
Is you crystal value 27 MHz? Sorry for the obvious question, but it is good to know! Thank you.
Yes it is. Its visibly displayed at 6:00 on the bottom right corner of the oscilloscope screen.
@@EvanVanderStoep Thank you for your reply in clarifying this important piece of information. Wish you great health. Have fun building things.
Will the frequency change slightly on the crystal if you change the resistor and capacitor values???
Hi, just subbed, great chanel. How can i use this circut to drive a very small solenoid? Cheers
hello a question can I use 220 or 221 pf instead of 222 pf
Yes
@@learnelectronics thks y very much good news 👍
I have used the same components except the transistor. I used bc547. But it does not oscillate. Why it does not oscillate?
very clear & simple. How to generate 50 KHz frequency? what adjustment should we make to this layout?
Hi :D What is the speed of the crystal?
6:11 on the oscilloscope. The frequency of the crystal is 26995khz.
nice video was wondering how could I sell the colpitts oscillator idea to a younger generation
I'm a little disappointed your not using the red dry erase markers...
Hi Paul, hope you are well! I know it is an old video but I tried to replicate it with a 4 mhz crystal, there was output for a few seconds and then zero; I tried different resistors caps. but same results. Any ideas would be appreciated. John
Keep only one capacitor of 220 pF between the Base and Emitter of the transistor. Remove the other capacitor between Emitter and Ground. Tested and it works OK.
Como se puede modular este oscilador.....guracias
what is frequency coverage of tester?
Is this project for gsm signal amp?
you list all the parts but you forget the most important one, the crystal.
6:11 on the oscilloscope. The frequency of the crystal is 26995khz.
@@Mahia965 lol i guess i didn't get that :D thanks
Sir transistor ku led ni parallel ga connect chesthe chalu ........
exactly what I was looking for. big like from me
How do u determine the frequency?
Can this produce audible signal? Or is the frequency too high?
Other Colpitts oscillators can produce audio signals, but Crystals usually start on the hundreds of kHz and go up to Mhz - well out of the audio spectrum. Try a LC Colpitts circuit for audio.
@@paulperano9236 OK thanks 🙂
@@paulperano9236 Thank you.
@@poykehmusic If you want to make some audio frequencies try the XR2206 and feed it through a simple amplifier. With a spreadsheet you can easily work out a range of timing capacitors to go with the variable resistor to make the required tones. Cheap and not to difficult, see the datasheet. I've been playing with just that and am getting ready to put in a case with a cheap frequency meter - all from Uncle Ali, (cheapskate me).
Please sent me the circuit Diagram
Thanks a lot for sharing ... keep it up ..
Thanks for the video, man! Very helpful!
+MrMyutubechannel Welcome
I would like to have a frequency of 50 MHz at the output, which crystal do you recommend? Thank you.
I think it must be 16 MHz.
How can I make this temp stable???
Thank you so much sir, you are helping me out every time.
priceless effort!
From where we get crystal
amazon ebay etc
can someone explain the significance of the frequency written on 2-pin crystal oscillators?
@@awaismushtaq5719 thank you so much! 🙏🏾
Nice video, thanks :)
Does the frequency of crystal affects the overall frequency of the oscillator?? If yes, then if I use a 1Mhz crystal would I get same or different value of frequency..
yes I think so
how do i design a 1.35 Mhz oscillator
What one would need to do to lock the frequency to 50 or 60 hertz in colpitts oscillator?
Just use elm446 with 4mhz.
What are the values of the capacitors and resistor values if i use a 1Mhz crystal
Doesn't work
I have build this circuit and used a power supply for the voltage supply. It was very unstable. Then I used a 9 Volt block battery. After that the circuit was extremely stable!
Will connecting a potentiometer in a circuit the right way, allow me to change the output frequency?
Yes
Thank you for the video - great tutorial. Forgive a beginner question though - after wiring in a 26.5810 crystal into the circuit (everything else the same) I can only get it to oscillate at 8.86 Mhz - exactly one third of the printed value. What am I doing wrong?
+caliphaxable Hmm, I have no idea why it would do that.
I changed the crystal to a different set of 4, 6 and 12mhz crystals and it functioned fine. Busted 26 Mhz crystal perhaps? Thanks again
@caliphaxable, It may be that your tank circuit is not tuned close enough to work with the 26 Mhz crystal. I recommend you check out th-cam.com/video/I4bAfDu6F1k/w-d-xo.html (another TH-cam video on the subject that explains the circuit and a good deal of the math. If that doesn't clear it up, study RC reactance, RL reactance, and RCL reactance. I hope this helps....
You might want to check the sampling rate of your oscilloscope. I have a relatively cheap one that has a max sampling rate of 50 MHz. It thinks that a crystal oscillating at 27 MHz is only oscillating at around 9 MHz, and I'm pretty sure that it's because the sampling resolution is just too imprecise to get accurate measurements at such (relatively) high frequencies.
Thanks for the tips guys I will check both out
Purely superficial information. No discussion about the theory of operation and expected voltages at specific nodes.
@@Rev22-21 Stupid ass !!!
point is would the 2n2222 drive run a bfg135