Maker Lab #1 Analog Signal Generators: XR2206 vs ICL8038
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- čas přidán 23. 07. 2024
- On this new videos series I'll try my best to help you built your
first electronics/embedded systems/maker home laboratory.
Sorry for the camera quality, I'm still using a webcam...
OST: track: Sarif Industries
album: Deus Ex Human Revolution
composer: Michael McCann
00:00 0 - intro
01:31 1 - XR2206's datasheet
02:56 2 - ICL8038's datasheet
04:13 3 - comparing the kits
05:27 4 - XR2206 kit assembly
09:59 5 - ICL8038 kit assembly
11:50 6 - XR2206 test
22:07 7 - ICL8038 test
31:37 8 - conclusion - Auta a dopravní prostředky
The XR2206 sine is CRAP!!!!!!!!!!!! Use the scope FFT and you will see it has pile of harmonics that should not be there!!!!!!!!!!
To be fair, both are not that great when it comes to sines... BUT the triangles are actually really crispy.
Sines are actually the hardest signal to get for cheap unfortunately...
It is not the XR2206, it is the circuit design that is crap. For the XR2206 you must adjust the resistance between pins 13 and 14 to get the least distortion. With proper adjustment the XR2206 can deliver less than 0.5% distortion.
@@dartplayer170 There is a such thing as fakes of the Shenzhen variety as well. I honestly don't mind clones/copies/knockoffs as long as they meet or exceed the specs.
The XR2206 has jitter problems above 12V and the increase in amplitude that you get is minimal. That is why they suggest to use 9-12V
Great presentation, thanks!
Very good comparison of those two cheap modules. I wanted to play with them but I choosed XR2206 one just because many years ago I made a quite complex function generator with few of them (it had AM, FSK, sweep). Altough is a clone (fake) IC, is pretty good if you know what to expect; i mean for audio frequency is almost perfect. And that if you work clean and make some improvements.
I built my kit but used a symetric power supply +/-5V (the output is ground refferenced, no need any capacitor to block DC). I also used a multiturn potentiometer to adjust the frequency instead of those fine and coarse ones. I borrowed from datasheet the symmetry circuit and I think that I improved the circuit quite a lot. For sure, the sine wave is not perfect, but for audio (and beyond, up to 150KHz) is very good. As for the square wave, I used a 7414 to have a proper TTL output.
Great video, i remember messing with XR2206 and a speaker until i got my LFG-1300s
Cant wait to find more videos from you, you seem funny and relatable
thank you so much! I'm stuck with some IRL problems at the moment but can't wait to go back to making videos
Nice wit some DX music in the background :D
thanks :)
Great video, I believe it is harder to get cheap electronics parts in Brazil compared to my home (UK) and so this is a great idea, keep up the good work Sir ! might be interesting to use the 'Math' function on your Rigol and have a look at the FFT for the Sine Waves as this would reveal all !!....If you want a very clean Sine and a bit of theory thrown in for good measure you might try looking at 'Wien Bridge Oscillators' fun to play with and can achieve THDs below -60 dBm...cheers.
thanks for the feedback! Nice to know. I actually looked at the FFT of the sine and it is actually really decent for such a cheap equipment.
@@madrigo well that's a surprise ! I expected quite a bit of harmonic distortion in there so I will see if I still have my kit that I bought years and years ago and have a play....cheers 😃
The sine wave is actually generated by softly clipping the tops of the triangle waves. The 8038 has provision to trim the amounts of clipping with those two small preset pots, so you should select sine output at some mid-band frequency and 50% duty cycle, then use the FFT scope function to trim out as many harmonics as you can. Incidentally, these sort of kits have crappy opamps in the output buffers with appalling slew rates, so best to keep the amplitudes small -- say no more than 1V to 2V pp, and don't expect the high frequencies to be particularly usable. Used with these sort of limitations in mind, these kits can be excellent value for money.
Hey Andy!
Hey !@@uni-byte
You don't need to use hot glue. You have to mount 4 short screws in the corners of PCB, than nut on the oposite side of PCB act as a distance and thats it. No need to screw PCB into the backplate. Then you just lay it loosely on a backplate, with the ends of the screws in the holes and mount the rest of the enclosure over it. When you finish, everything will stay solid. Just remember, to mount capacitors horizontal, other way it will be a little tight.
good to know!!
Does the triangle/sine output work better if the square output is left open? And are the voltage and current in phase? 🤔 (For the xr)
i didnt have a load plugged in it. Not an external one at least. The output went straight into the osc. So all outputs are open.
@@madrigo your scope still loads the circuit. At 1x it's impedance is 50Ω and at 10x it's 1MΩ.
oh you mean that. I did not test separately the outputs so don't know about the square.
The square wave comes from the output of a comparator that is fed from the triangle wave. The triangle wave is produced by linearly charging and discharging a capacitor from two current sources which are switched by the state of the square wave. So, in a simple circuit, loading the square wave excessively could affect the triangle wave and hence the sine wave. However, in these modules, the outputs are usually buffered by a (crappy) opamp, which should give sufficient isolation and prevent such interactions. The outputs are therefore relatively low impedance voltage sources, so the voltage and current are naturally in phase if driving a resistive load. My scope probes are 1MΩ at x1 and 10MΩ at x10. YMMV.
Your square wave would likely be a bit better, if you would set the probe to x10. The x1 mode has too much capacitance that together the pull up resistor slows down the positive transition.
interesting! Gonna check that
You must be a Deus Ex fan, ...could not help but notice the background music! :)
Heeeey!! A man with impeccable taste indeed! Human revolution has a special place in my heart, cant deny!
OK VERY Good❤❤🙏
XR2206 would surely do for audio work? I do a lot of mixer, transducers, valve/tube amps etc! Excellent presentation ! Fraser
Hi there! Yes it would work, but as you saw in the video, the quality of the device is very limited. Could be a case of cheap knockoffs from china as a lot of people in the comment section mentioned. If you work with audio and want to simply test equipment this could work, yes, but with some limitations. I would rather put some extra dollars in and get something more reliable and trustworthy.
Your probably right, I have an old Heathkit signal generator which covers audio and rf bands too that still works! It would be handy to have something smaller that can be battery powered and hum free! I am retired now so it’s only a hobby but will keep my eyes on and maybe pick up a kit or something that can cover the audio band and am rf bands! Thank you for your help! Fraser
@@elsaarmstrong-zp6ng my pleasure to help. If you want to reach RF then you definitely need a higher quality signal gen.
What is minimum and maximum amplitude of sine wave?
XR2206 is almost rail-to-rail. the ICL is less than that.
I find it easier to solder the small components 1st. Nice video, maybe leave the background music out..👍
thank you. I'll think about the soundtrack!
These chips must be made by Chinese 3rd party makers. The original chips are old ! 1970s old. I made my first function generator with the original Intersil 8038, back then, while I still was a poor kid in high school. Don't know much about the Exar part (XR2206), but the 8038 uses the triangle wave and applies to a "piecewise linear network" to form the sinewave. Its not the best.
Many years later, in the 1990s, to get a cleaner sinewave, I use a multi-stage switched capacitor filter, to filter a squarewave into the sinewave. These switched cap filter's cutoff freq are either 1/50 or 1/100 of the filters clock frequency. So you make a your "clock", and divide it by 100 (or 50), and apply both to the switch capped chip, and get a nice sinewave out.
Recently, I've been getting back into tubes, and just made a Wien bridge oscillator. Simple. Two tubes, and an old fashion 5W incandescent "nite lite" bulb. The bulb is a non-linear resistor, and it only sees a couple of volts. Nowhere close to its rated voltage, so it should last forever.
Hi!
How did you load the gen for your test?
I got trapped and got weird things bcse I frogotmy scope loads about a megohm and got weird sigs.
Terminating with 50 ohm should be OK though I ain't got a clue what the actual output impedance is.
You get what you paid for and as long as you got a scope, you can use it .
Remember offset will cause sig to clip depending on amplitude.
Take caution when DC coupled, current might not be limited and you may fry your board.
Ask me how I know.
My 2 cts.
Antoine, operator of F8EBL station.
I used the gen open output. No load. I wanted to examine the quality of the gens without a load. This is important to me because sometimes I will use them for signal purposes. A good gen should work ok without a load on the output. These two did not work fantastic but yes, they could improve a little with some load and the output. Something to investigate maybe? Cheers!
On the 8038 kit a jumper is labelled SIN or TAI. I kept thinking "What is TAI" until I realized it is a typo and it was supposed to be TRI. Kits of this type are made as cheap as possible and are typically based on the example circuit shown in the datasheet. Some years ago I saw a circuit using the 2206 that got better results from the chip by wiring things up based on a better understanding of how the chip operated. I have a document for a very capable signal generator project using the 8038 that goes much beyond the version shown in this video. In general, the 8038 is the better chip. It is all in how you use them that will determine the type of results you can get from using either the 8038 or the 2206.
Wiki says the 8038 was discontinued by the manufacturer in 2002. I would guess the reason it is so cheap is the Chinese copied the chip since the IP was so old and the chip so simple to make then they would be paying pence for it. China uses a lot of these old chips. They have their uses if you just want standard performance, but not really what you would use for test equipment.
Ingles bom parça
vlw meu bruxo
As I saw in another video for these kits, one of the pots is not like the others and can do what you are showing. Might just be a crap kit also.
how did you get a visa to brasil? are you rich?
Maybe I don't need a visa because maybe I'm brazilian? kkk
@@madrigo Thank you. I heard you say you "live in Brazil" but never mentioned Brazilian and with your thick English accent I figured you can not be American. To live in a country is totally different from being a local. Good video, though. There are two other options for function generators, the uni-t that is a relatively good Chinese product (everything in the world is probably Chinese, the much better stuff are Taiwanese) for the money, but it is still 20-40 times the price. The other is the Si5351 and an arduino or simply one of the arduino derivatives/cousines that run at a much higher clock so you can either store samples of one cycle of every waveform in your code or do a simple polynomial interpolation for one cycle and only store the coefficients.
@@engineereuler1762 Hey there. I thought it was pretty clear that I'm Brazilian. I wanted to show the super cheap because everything professional is much more expensive. And the digital option Is better made with a DDS system with an ESP32. I know this because I've made one and its in the channel!
@@madrigo Yeah I think you said your nationality, good work ! and you sound like a proud Brazilian who speaks great English and I'm an Englishman so I know !!.......cheers
Thank you for your kind words @@andymouse. I'm trying to make my english sound as good as I can and yes, proud to be Brazilian.
Mmm, Deus Ex music.
A man of culture I see
@@madrigo I absolutely asked for this.
Hm, about those generators, I thought MAX038 was the copy of ICL8038, apparently those are VERY different.
@@VEC7ORlt I might be working with some really dodgy counterfeits in here as some other comments already said. But even being kinda not great, they are amazing for the price.
It sure took you long enough to stop that scope waveform from rolling like it was for a while there... Some years ago I wanted a function generator, so I decided to build one. Way cheaper than what I would have had to pay to buy one in those days. I see where these days they seem to routinely go up to 1 MHz, but for me the audio range was going to be good enough. The ICL8038 would go 20 Hz to 20 KHz without any sort of bandswitching, which is what I wanted. I could not see a way to do this with the XR2206, which I am seeing much favored by the chinese vendors these days. I did build it, powering it with a dual-voltage power supply regulated with a couple of zener diodes (probably an area for improvement) and also have provision for applying a DC offset to the output signal. I intend to provide a TTL-compatible output but didn't have the right buffer chip handy to do that so the BNC connector is there but not presently connected and I haven't missed it. I also have not included any provision for varying the duty cycle of the waveform. For the most part it works well but when you get really low in frequency the sinewave goes to shit. Maybe one of these days I'll figure out why that is...
Negative offset is fine and expected for a function generator. The Arduino monkey-see, monkey-do types you speak of need to learn some electronics and they'll get by a bit better. You also have to be aware of few things. First, these are not DDS generators and being cheap little singe chip generators that do so much, you can't expect them to produce the same performance you'd get from a real instrument. Next, given the price you paid these are, with almost 100% certainty, counterfeit chips that DO NOT work properly. Also, the XR kit has a positive offset you can't remove. To me, that's a total fail. I would prefer a "real" ICL8038.
Hard not to get knock-offs these days, with counterfeits flooding the market more and more...
Le xr2206 est vieux, très vieux...
Je constate que produire une sinusoide reste problématique dès lors qu'on veut modifier l'amplitude ou la fréquence :
Rien de nouveau hélas dans ce domaine Grand Public. Pourtant On sait faire mieux...
Effectivement tu as raison ils sont vieux ! et oui, la sinusoïde parfaite est difficile à fabriquer. J'ai joué avec des "oscillateurs de pont de Wien stabilisés par ampoule" et c'est assez fascinant et de très bonnes ondes sinusoïdales propres peuvent être obtenues ... à votre santé.
The voltage limits on the XCR2206 is because the XR2206 chip is a FAKE that cannot handle the full voltage range.
Not surprising at all...
That's one reason. The other one, y'know, is that the electrolytics used to smooth the supply are usually the lowest possible rating that they could get away with.
All the chips shown here are fakes. Every single one.
You might be interested in XR2206 design errors video czcams.com/video/f_gnoU22Dj0/video.html
I was about to post this link. That video explains a lot of the issues found in this one. Fake ICs, lack o output capacitor (for offset 0v), too big of a voltage swing at min setting, backward potentiometers... that said, I am designing my own board for a XR2206 using the modifications on that video (and also my own little mods) so I can fit it in a 1590B hammond aluminum case, like a guitar effect pedal. I hope everythings goes smoothly. Fingers crossed.
MAX038 based is way better (goes to 20Mhz). :)
Correct, but the factory burned down decades ago. The Chinese ones might be marked MAX038, but good luck getting them to work. I tried one, and it drew a big current and produced no output. Complained to the supplier who claimed that he tests each chip before dispatch. I told him that I was pleased to know that, and would he please supply me with the schematic of his test circuit, because the one provided by the original manufacturer produced zero output. He then refunded my $10. He was full of BS. The plastic moulding was wrong, and the white bar to the left of the MAX038 was wrongly located.
The ICL8038 kit is using op-amps way too low bandwidth & V/uS ability! Crap design as expected! :(
Wow, even the ICL8038 is CRAP for operation! I think the Chinese need better design engineers. Sadly these bad designs are typical for Chinese stuff. :(
The saturation and general NO trust of control is CRAP CRAP CRAP CRAP CRAP!!!!!!!!!!!!!!!!!!!!!!!!