Build A Low Cost 10KHz-255MHz RF Signal Generator Project - Part 2
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- čas přidán 12. 09. 2022
- This video is kindly sponsored by PCBway. Please give PCBWay a try for all your PCB needs. / pcbway
Here is Part 2 of the Low Cost RF Signal Generator project, kindly sponsored by PCBWay. You can find part 1 here • Help!!! My Electronics...
*AM Modulator circuit by kind permission of Don at Restore Old Radios (CZcams channel)
Check him out, he's a nice guy* / restoreoldradios
If you use this link when creating a new PCBWay account and you will receive a free $5 discount coupon: www.pcbway.com/setinvite.aspx...
Links mentioned in this video:
PCBWay 10KHz - 255MHz RF Signal Generator Project
www.pcbway.com/project/sharep...
AM/FM Radio Fault Finding
• Portable CD Player / R...
This project on arduino.cc
create.arduino.cc/projecthub/...
The Arduino Sketch for this version and the upgraded one with a larger display are on LER Discord server
Arduino IDE Download
www.arduino.cc/en/software
Video - FIX Cheap Arduino (Clone) Will Not Detect
• How to FIX Arduino Not...
Parts Required To Build This Project. These are affiliate links, LER makes a small commission from anything you order, but you pay the normal price
Arduino Nano R3 (ATMEGA328 version required!)
www.aliexpress.com/item/10050...
Adafruit SSD1306 128X64 OLED DISPLAY
www.aliexpress.com/item/10050...
Adafruit SI5351 CLOCK GEN MODULE
www.aliexpress.com/item/40001...
Rotary Encoder with Push-Button
www.aliexpress.com/item/10000...
78M05 / 78M08 (I didn't work out yet which is the correct part so I'm ordering both)
www.aliexpress.com/item/10050...
78M05/78M06/78M08/78M09/78M12/78M15 Pack (5 of each - excellent value for money)
www.aliexpress.com/item/10050...
100uH Inductor
www.aliexpress.com/item/40012...
1N4007
www.aliexpress.com/item/10050...
SMA Connector (Type 10)
www.aliexpress.com/item/10050...
DC Jack Socket
www.aliexpress.com/item/10050...
SPST Toggle Switch (two required)
www.aliexpress.com/item/10050...
Momentary Push Button Switch (NO)
www.aliexpress.com/item/40001...
All other parts are standard resistors and capacitors - you most likely have these already.
300W Electronic Load Project
www.pcbway.com/project/sharep...
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*Big shout out to Don at Restore Old Radios for his help with the AM Modulator circuit. Check his channel out, he's one of the good guys*
czcams.com/users/RestoreOldRadios
lol I watching this today , and noticed when you said just 10 more subs to reach 10k , well one year passed and now you are at 133k subs, i think that is great job.
Looking into the datasheet, the Si5351 is just a digital clock generator which will always output a square wave. Distortions must come from other components on the board or your leads. Output impedance of the IC is 50-60 ohms. Hence you may need a similiar termination resistor for higher frequencies.
Either the scope probe or the components on the RF output are forming a low pass filter, causing the square wave to lose its high frequency components and become a sinewave.
@@TheEmbeddedHobbyist or the scope doesn't have enough bandwidth to be able to interpret the square wave at higher frequencies. In terms of wave composition, a true square wave is one of the most complex. At bandwidth limits, all a scope will see of a square wave is its carrier sine component.
@@ivolol At 225MHz you need a good scope and better than the run of the mill scope probes. I don't expect my 100MHz scope would show a true square wave anywhere close to 100MHz. It would never cope with the harmonics.
@@TheEmbeddedHobbyist
I was about sending my new UNI-T UPO1202CS back thinking it's faulty, I was measuring the signal of the si5351 and once I increase the si5351 frequency above 10mhz my oscilloscope start showing out of shape square waves, the more I increase the frequency the more it becomes like a sinewave, until someone told me that the si5351 is not an accurate signal reference and my 200mhz oscilloscope can only measure squarewaves at a frequency less than 1/3 of the oscilloscope bandwidth, but on paper a 200mhz oscilloscope shouldn't have a problem with showing a perfect squarewave at 40mhz frequency, in my case, my oscilloscope is showing a sinewave at 40mhz instead of squarewave.
at this point I am completely confused and I don't know if I should send my oscilloscope back or keep it, and I don't have other accurate signal references to know if the problem is with the oscilloscope or the si5351.
Heya I love to see these DIY projects
When your signal's frequency gets near the maximum frequency of your scope, then the only waveform that the scope will know to be able to "interpret" from the datapoints it is getting in, is a pure sine wave.
To be able to display a more complex waveform (if indeed, the waveform was more complex in reality) it would need to sample the data at much higher frequency (which would make it a higher bandwidth-rated scope to begin with) to again be able to tell the complexities of the waveform apart.
Essentially the scope measures a bunch of dots in time along the true waveform. When it is a slow wave of some description, it can measure many many dots in each period of the wave, and therefore reconstruct a very detailed and accurate picture of the waveform for each period. When the wave form is near the scope's sampling frequency, it really only gets one or two dots per period. Therefore it has no way to reconstruct if the wave was some crazy complex one or just a sine wave oscillating at such a frequency that it made the one or two dots it sees in each period. So it is essentially forced therefore to presume it is just measuring a sine wave at that frequency.
Theoretically this rule comes from the Nyquist-Shannon sampling theorem.
One could just as easily solder the Si5351 at the underside of the board; less introduced capacity and as added benefit is that the connectors will come out in the direction of the side of the case as well as having more clearance.
Any video on explaining the working of 433mhz transmitter and receiver module used for RC toys
I've heard loads of times not to mix lead & lead free solder. Something about weak joints // Eutectic melt point changes.
I feel like solder is the wild wild west caz you can't know what "they" used on some random board. Also>> Is the roll that we purchase exactly what is on the label ?? > if it is a high mechanical stress solder job then I remove all old solder as best as possible and apply new "known" solder. Prefer=60/40 for mechanical for sure. Absolutely 60/40 for high stress parts. (connectors / cables / interfaces)
If it's a more static solder job, like something on a circuit board I don't bother being careful and just re-use as much as possible. ROHS solder for board stuff.
Also, just as a personal habit I flex my solder joints a little bit. Just push with a screw driver to make sure it's stuck good or something like that just to make sure it actually happened. Looks can be deceiving.
If you intend putting this in a case flip the pin-header .
Mount the sig gen unit underneath main PCB ......
🔥🔥🔥
one small point about the signal gen the square wave will give an output with lots of harmonics not good for fault finding sine wave will be ok.
the modulator is an interesting circuit that was used in some cheap rf generators.
finaly the ring tester will be great if it works on the inductors used in SMPS at the moment i use the callibration output of my scope and try and count the rings but its pretty impricise at low mh
I am wondering if the sig gen is really giving a square-ish wave output at frequencies below about 3.75MHz or if it is something to do with my scope or having no antenna/load on the generator?
@@LearnElectronicsRepair When you order your SMA pigtails, connectors etc. include a 50 Ohm terminator. Some of the ringing may also be due to scope probe compensation (decent scope probes have adjusters on them).
@@ralphj4012 yeah I will try that. My scope probes has 'adjusters' on them like you mention but I thought they only affect the waveform if you are using x10 setting on the probe.
@@LearnElectronicsRepair Usually (but I suspect not always on some probes) the adjusters alter the probe's capacitance, nothing to do with range setting (unless range means affect by frequency). The adjusters alter the wave shape, more so at high frequencies. Ringing can be caused by unterminated RF inputs, hence the feed-through SMA 50 Ohm terminator (though I have no idea what the anticipated output impedance of your generator is / meant to be). Of course, the scope probes must also be suitable for the frequency range being measured and always use very short scope ground cables.
Can you give high voltage input to this to get same amplitude for output sine wave?
Cool...
Id be guessing the tx is transmit and rx is receive frequency with that switch
What is the resolution for the digital output?
Hey Diky, you said at the beginning of the video that you was going to put a link up to a radio repair video of yours but I can't find it in the links you provided in the description, I've tried searching for it but I can't find it anywhere, could I be a pain in the arse and ask you for a link to it please mate? 👍🏻 😁
Ahh sorry - here it is. I include a quick introduction into how radio works and how to troubleshoot it.
czcams.com/video/2pAp1R24XyY/video.html
I forgot to ask ... on your inexpensive psu, when you switch off & on does it dump any unexpected power out onto its terminals or is it safe to leave connected?
I didn't measure it, but I turned it on and off several times with this project attached (and the project does not contain it's own voltage regulator at the moment) to no harm. I don't know whether this is due to the fact the PSU is not outputting any excessive voltage or because the Arduino nano and Adafruit modules have their own 3.3V regulator on board. I'm deliberately using the cheap PSU to see how it compares to using either of my more expensive linear bench power supplies
@@LearnElectronicsRepair .. thx, useful to study, and well done with the project. Keep up the great work 😀👍
@@CTCTraining1 Cheers Chris. I'm quite aware of why you are wary about the cheap bench PSU - I will keep on using it in videos to see how it performs. It's not like I am biased as I have two others i can use, I'm just open minded about it.
These kit builds don't interest me so much, but I'm sure many will get a thrill with them.
I hope you still make some time for your repairing video's, your fault finding methods and your hand written schematics and explanations. I get a lot out of those.
Cheers!
I'm kinda mixing it up a bit but I will certainly continue to do a lot more repair videos, no worries,
@@LearnElectronicsRepair All good brother, I'll watch along as much as I can and maybe It'll perk my curiosity a bit more. Cheers!
14:31 - Tx and Rx designate transmit and receive, respectively.
At about 15:40
The overshoot on the square wave is almost certainly the result of poor probing technique.
I have no idea where the scope ground lead is connected or how long it is, but it needs to be a short as possible because it produces a resonant circuit in conjunction with the probe capacitance. For higher frequencies the best thing to use is a probe tip grounder. FET probes are very good but expensive, Contrary to common belief they are not especially high input resistance, but the capacitance at the tip is very low - 1 to 2 pF typically with moderate-bandwidth types. The low capacitance reduces circuit loading at high frequency and lessens issues with ground lead inductance. With low impedance sources 500 ohm probes can perform well.
EDIT: If the circuit will drive 50 ohms, the best thing to do if you don't have high-end probes is to use a 50 ohm terminator at the scope and a 50 ohm coax to connect to the circuit under test. Both terminator and coax should be good quality. Lots of higher-end scopes have switchable 50 ohm termination built in.
I have two samples of Kaisi solder that are complete rubbish - along with another Chinesium brand.
The only thing I will use them for anymore, is as 'fodder solder'... To put on the iron before putting it away, to protect the tip - which then gets brass-sponged away before next use with PROPER SOLDER like Kester!
Projects ?? hmmm...
What about upgrades for the oscilloscope ? Differential probes ? HV probes ? Current Probes ?
Years ago I watched a Tektronix product release vid and there was some strange scope probe which looked like a mini 'metal detector' like for gold hunting. never seen it again. have no clue what it was called. He just waved it above a computer motherboard and it picked up everything.
Just use header pins just like on the Arduino, you must have loads about ! as opposed to chopping up a socket you can buy a lifetime's supply (and they are useful) for 2 quid !....cheers.
Fair point but I kinda got a lifetime supply of IC sockets when Maplins (you will kow if you are in the UK) closed down
@@LearnElectronicsRepair Lol yeah RIP Maplin !
Use a 50 ohm terminator resistor might eliminate that strange odd waveform
If the circuit will drive 50 ohms, the best thing to do if you don't have high-end probes is to use a 50 ohm terminator at the scope and a 50 ohm coax to connect to the circuit under test. Both terminator and coax should be good quality. Lots of higher-end scopes have switchable 50 ohm termination built in.
Great video but a warning ...kaisi solder is not good at all , I do not recommend anyone using that solder.
What's wrong with it John? It seemed to work OK but I'm not totally sure about it myself, it felt a bit 'odd' somehow that I can't quite put my finger on.
@@LearnElectronicsRepair From all the Chinese brands it's the one I truly dislike the most ... There are some videos online comparing cheap Chinese solders brands and it is clear ..kaisi is the worse ... I can not put the link in here because lately yt as been erasing my comments with links ... (not kidding.) I will put the link on my next reply.
@@LearnElectronicsRepair Here is one compaarison video: czcams.com/video/tQBNcdbWldY/video.html
@@John_Smith__ You are not the only one having comments removed by YT and believe me it is not me doing it. I'm quite happy to accept any comments here. I do agree there is something a bit odd about that solder. I bought two cheap brands from aliexpress and the other one seems 'nicer' or some reason. Having said that even the Kaisi one is better than that lead free shite. I also have the Wuppertal one to try. So far I still prefer my Mechanix that I had a 500gm roll of for many years until it just ran out. Strange these 60:40 solders can be different
@@LearnElectronicsRepair Oh my friend I know it is not you, it is the algo from yt ... it is strange since I was trying to post comments with the due reference and used a yt video and then every time I did that the video would be removed ... like after a couple of minutes ...it is a yt thing, or was since my new comment now contains the link to a test video. It may also be the case for linking to products that may be confused with commercial spam ... I don't know. In this case however it worked.
Also SDG channel made a very extensive test of many solder types ( czcams.com/video/zZ9wxs6xuYU/video.html ) ... and indeed I think it is the level of Purity used on the Tin and Lead content of the solder. I suspect the very cheap Solder wires from China are using "spent" solder from other applications or simply use low grade purity Tin and Lead. And I agree with you, anything is better then non-leaded solder 😀
About the Wuppertal the one you have on the video ... Those are just another Level of Quality ... Way better then anything we can buy. Stuff like Kester, MGChemicals, Wuppertal, and some other known brands are top quality. From aliex I bought a brand called Best (60/40 0.3mm wire 500g ) and it is perfectly acceptable. Also on ebay you can find a roll of 250g of several diameters from a brand sold in Japan called Sanki. I also can say that is a good 60/40 solder wire (search for sanki solder on ebay).
Yes, EEVblog does an excellent job at covering some of the probing problems you experienced here in this 25 min vid, definitely worth a watch... czcams.com/video/PPgxFd97taY/video.html
Thanks Adrian, I was sort of aware of the posible problems and I will defintiely watch that 🙂
@@LearnElectronicsRepair I thought as much as you mentioned about possible probing issues. I watched it recently as I had the same issues with my function generator and wanted to learn exactly what was happening and how to avoid it effectively. Dave Jones does seem to put out some good videos on the finer aspects of such subjects and is a good learning resource, whether your new to the game or just refreshing your memory.
1/10 the price of a tinySA