Function Generator Kit Build & Build & Fix & Test & Bin? - 12v Solar Shed

This video starts off well but unfortunately things don't finish off that way. Sometimes electronics is like that - sometimes youtube is like that! Click More for links and the like...
This function generator kit uses an Atmel ATMega16 and very few other active components to create signals. It uses a LM358 dual op-amp to adjust the amplitude and offset of the signal and this requires a +12 volt and -12 volt rail. It's a fairly straight forward build assuming all the bits arrive in good condition.
I bought this because my previous function generator had no way of displaying the signal frequency that was being generated. You had to determine that with an oscilloscope or frequency counter.
This function generator has it's issues though. If you want to skip to the testing phase then jump to 18:00
Links:
Wikipedia R-2R Resistor Network Ladder: en.wikipedia.org/wiki/Resisto...
My Dual Rail PSU Kit Build Video: • USB Boost DC 5-24V Dua...
Julian Ilett Dual Rail PSU Kit Build Video: / xmnjillrmoy4
ScienceProg.Com Design Blog: www.scienceprog.com/avr-dds-si...
Items used in this video:
❗️These links are affiliated and I may earn a small commission if you purchase❗️
ATMega16 Function Generator Kit: goo.gl/zGlMYw
Dual Rail Power Supply Kit: goo.gl/lhSw1G
Vici VC99 Multimeter: goo.gl/GdFAWT
ATMega328 Transistor Tester Kit: goo.gl/m8YQ4T
Owon Oscilloscope: goo.gl/vmgem0

[@aspendell209]

Adam, a Fail kit build is almost more valuable to your faithful viewers. You have saved all your Patrons money that they can now donate to your continued efforts to suss these things out for us ;) Great video! glad you stuck with to the end, so we know for sure what was going on ~Cheers~.

[@deangreenhough3479]

Always good to see someone you respect going through the mill. We have all been there, really really pleased you didn't bin this. For me, this type of video is golden. I applaud you posting it and encourage you to do more like this. So much more is learned when you see someone searching for an answer, than just watching a faultless smooth post👏👏👏 Big old chufty badge for you👍

[@AdamWelchUK]

+Dean Greenhough Thanks Dean - I won't plan to have issues but I'll try to keep them in when I do. I've been surprised by the positive comments on this video but also very pleased. While you're on though (saying such nice things) I should also point out that I enjoy reading all your comments. I like it when your avatar pops up on my phone to notify me - I know there's something good to read. Plus I like chickens. :-)

[@peterfielden-weston7560]

I bought one of these DDS generators but didn't have any problems with it. My Atmega chip was also in polystyrene,but no damage or pins bent. I fitted this into a project box and had to dismount the potentiometers and BNC connectors to get enough room for the pot knobs to fit. I also needed to buy some new push buttons with much longer posts. I also mounted one of the split rail supplies under the DDS board. The whole thing works great, if you discount the cosmetic appearance as I couldn't get the six buttons lined up properly and bodged the holes terribly. Still in all it was a good build. And then I went and bought a 24MHz DDS box, also from the same supplier. :)

[@AdamWelchUK]

+Peter Fielden-Weston Glad it worked well for you. Sounds like a nice project. Cheers

[@roberteliassen5020]

Thanks Adam! Really interesting and fun to watch. Thumbs up!

[@AdamWelchUK]

+Robert Eliassen Cheers.

[@joinedupjon]

Enjoyed watching someone else deal with the frustration, dig in and get a result. on a point of pedantry the exposure varied considerably through the video and detracted a bit - realise it was a montage filmed over many days.

[@AdamWelchUK]

Cheers - yes exposure levels and white balance were a distraction sorry. I'd like to fix these throughout a video normally, but finding a happy balance is not always easy. Leaving it on automatic also has it's issues when trying to film screens. I'll be completely honest - I thought I had them about right but then realized the brightness on my phone screen was lower! Sorry about that. I'll try and do better next time. Thanks again.

[@MixedGears]

I start to build this thing. THX for your debug procedure. It may be turns handy if there will be issues

[@Henryhaspants]

I learn more from a video when things go wrong.

[@AdamWelchUK]

Good to hear John - but I don't plan to do too many more videos where things go wrong all the time!

[@Henryhaspants]

Understood.

[@stevesm2010]

Great video. I really enjoyed it. I'm looking at function generators at the moment but I think I'll give this one a miss! :D

[@SpeccyMan]

The one I bought is the same basic design but it was ready built and had onboard voltage generation so it runs from a single supply. However it came with one slight issue which turned out to be easily fixed. The signal outputs were exactly half of the displayed frequency. The problem was the fuses in the ATmega16 hadn't been set correctly to use the crystal oscillator, it was running on the 8MHz internal oscillator instead. Luckily I have a USBASP AVR programmer and the PCB had a vacant space for a 2x5 programming header so it was 5 minutes work to fix the issue. Clearly quality control was non-existent where it was built but at least it does work. There is alternative firmware out there if you fancy tinkering with it further.

[@AdamWelchUK]

Thanks Nick. I have ordered a USBASP programmer and a zero insertion socketty thingy. I may well look up the alternative firmware. Mine does produce the right frequencies so clearly the fuses are correct but it does question the quality control.

[@9h5bmjason19]

Looks like you have some noise on the power lines ! . Mine works like a treat !

[@quantum5170]

Adam your video was very good and did enjoy watching the professional & quick explanations given without gibbering and hardly a pause between changing components. Could your psu been responsible for the spurious signal received? as for the major problems i do not know! ...but have certainly learned from yourself.

[@keithking1985]

Very nice👌

[@tonywalton1464]

I must be lucky or something. Built one of these yesterday and it worked fine first time (except I can't see anything sensible out of the HS output. Wonder if I've got a bent pin on the microcontroller...)

[@alien8r33d]

Have you checked the PCB for etching faults?

[@Ziggerzzz]

I built the same kit & the op amp went up in smoke ! , Replaced it with an NE5532P then all was good

[@AdamWelchUK]

Eek! I'll keep an eye on it. I've actually got a bag full of LM358s if required. :-)

[@mrjohhhnnnyyy5797]

I made this generator using info on the ScienceProg.com, and I have to say, it has some querks too. My don't freeze when you probe the HS output but tends to screw itself up when you switch it off. What I mean is when I unplug it (I have mains transformer+bridge+caps+regulator) from the mains, sometimes it displays rubbish on the screen and won't work anymore. I had to flash the chip few times, it drove me nuts :/ BTW, what about decoupling caps? Maybe you have a bad one, the uC needs a good decoupling, otherwise, it does weird stuff. Try to bodge some 100nF or larger ceramic caps in parallel to the existing ones.

[@AdamWelchUK]

I'm going to leave it to one side for a bit. I've had enough of it for now. However when I pluck up the courage I may well give your suggestions a try. Cheers.

[@KarlTheDingbat]

You have way more patience than I do, I would have taken a hammer to it.

[@AdamWelchUK]

+Karl the Dingbat Hopefully you had the patience to reach the end of the video without resorting to the same tool? :-)

[@caroman6761]

ecg looks like your's after getting the second generator complete ;-)

[@AdamWelchUK]

+CaroMan Ha! Yeah. After reviewing the video though I may have found it a bit more constant if I'd moved the trigger. I was a little worked up though ;-)

[@paulsengupta971]

One thing not tried was the second type of screen with the first board or vice versa. Perhaps the one type of screen isn't exactly the same as the other and pull too much current or something.

[@MegaTorgny]

Hi Adam,thanks for the video,sorry it doesnt worked as should

[@039dalekmoore2007]

i have one too i had the same problem with another kit not this one a frequency meter got 2 and both did not work just got rubbisb out of one and nothing out of the other...it really is hit or miss with the kits i am thinking the parts are pretty much not tested ...as my old lazy work mates at bhp used to say work no work same money boy ! they were pretty much right and the saying is correct here too...hope mine works ! but not hopeful !

[@jakobhovman]

Hello Adam... This is a very good video about "blind Kit building"...! I applauded you When you made the second board, to test the chip... Also, a opamp tester will be of great use in your shed. The Germans have a saying: "Wissen ist Gut, aber, Kontrollieren ist Besser...! When I get chips from ebay and they are Not protected, I ask ebay to return/refund.

[@AdamWelchUK]

We have a saying in England which is quite apt in this case... buy cheap, buy twice. It's a shame, even after all that time and effort it doesn't work terribly well. Oh well. Onto the next thing... Thanks Jakob

[@davelowe1977]

Oscillating op amp? Try decoupling the input rails close to the chip.

[@mrjohhhnnnyyy5797]

Might be the case, I had a similar issue with the other gear.

[@Luke-san]

Yup and also decouple the power rail as close to the + and - vs gnd. Use 100NF caps. Seen some funky outputs when either the input rails are (to) high impedance or when there are spikes on the Voltage rail. Might even be an earth loop. Maybe you can give it a second life. Troubleshooting what goes wrong and getting it right is part of all the fun and fulfillment .

[@mrjohhhnnnyyy5797]

Yeah, I mentioned decoupling caps in my other comment. I agree - troubleshooting and tweaking is the most fun part, and you learn a lot doing that.

[@brucewoods9377]

Can you change the op amp for a TL072?

[@andreweastland9634]

check the orientation of the switches

[@AdamWelchUK]

Yes I did check that on the original - I did consider that one of them may have been causing a short and confusing the ATMega or at least getting it stuck in a loop.

[@keithking1985]

Making me nervous coz I'm waiting for a kit build my self a dso shell... My first scope(ish). I hope I don't have any problems🙏😬

[@keithking1985]

P.s. What is ecg what dose it stand for/do???

[@maicod]

could the first opamp be damaged by the first kits circuit ?

[@maicod]

oh it was the second kits opamp that was faulty I think now

[@AdamWelchUK]

+Maico Yeah it was. The opamp shouldn't effect the atmega circuit though and I did remove it from the original circuit to check that. The first one seems to have come with a faulty pcb the second a dodgy opamp.

[@maicod]

***** yea it must be the first kits PCB circuit itsself. I was amazed the AtMegas were both fine.

[@RyanUptonInnovator]

Did you find out what went wrong with the first kit in the end?

[@HazeAnderson]

I believe there was a short in the LM358 chip?

[@aryeguetta8592]

Not sure if you know it already knows that already - I know it has been a VERY long time since you have made this BUT - I am not sure but maybe the reason that it does NOT work because of the Occilator capacitors and they should be 22pf and I am sure that you have soldered the wrong capacitor. that could be it. Not even sure if that may be the case BUT on 12:41 we see that you have yellow capacitors - that I am not sure the value of - instead of the original red ones... NOT sure if that may be the case But maybe :) I know that you have already used the original red ones, to begin with, but what makes you replace them? 4:42 are they OK? hope you will have it fixed.

[@robertkilbourne323]

Pity you had issues with this - mine worked perfectly... well, I have no oscilloscope, I just hooked a speaker up to it so I could hear the waveforms, but it seems to work fine. I noticed that you have to turn the output off before you can change waves / frequency, you can't just change it on the fly to use the unit as an oscillator. Obviously this is normal for the unit.

[@javierpallalorden]

Hi Adam, nice video, I think you could make a far better job yourself by using an Arduino and an AD9851.

[@AdamWelchUK]

This is probably true. For me kit builds are meant to be relaxing and educational. It certainly wasn't the former!

[@TheKetsa]

And it would make a very interesting video !

[@Mosolarfan]

I was hoping to see the hammer come out!!!!

[@AdamWelchUK]

+The Left Hand Almost :-)

[@electronics3992]

I broke this junk , when I power it up it stays on 0hz and u cannot change frequency !!

[@AdamWelchUK]

Sadly I was having similar issues.

[@alisonmarywrigglesworth4764]

Only the bottom of my screen worked, then something smoked. Still investigating.

[@AdamWelchUK]

+Alison Mary Wrigglesworth Well if you need any spares... :-)

[@alisonmarywrigglesworth4764]

Thanks I shall probably buy a second kit for spares, especially as I have fashioned a housing box from aluminum. Really enjoyed your video, well done.

[@AdamWelchUK]

Thanks very much - I was close to just deleting this video with all the trouble I had. Glad I didn't now.

[@kirkb4989]

If you would like another similar challenge, you may want to take a whack at an "RGB LED Heart Kit". I bought one, built it and had it act odd, then got another kit (like you did) to try to trouble shoot the first one but it did the SAME thing. They act sporadic just like your first build and I too replaced the caps, xtal and swapped processors. The really weird thing is that if you touch the xtal area of the board, it will sometimes spring to life. I have NOT tried looking at the fuse programming but I guess if I want these to work, that might be next. Here is a video of the failure: kzbin.info/www/bejne/mXuoZKSNesx_n9U and here is what it should look like: kzbin.info/www/bejne/qZmYZqh5oJWta5om37s Any ideas or is it the bin for these as well???

[@tonyl7418]

I know this is a year later....but you probably had a faulty circuit board. Even a trace hair of copper can cause a short. I have seen this happen in the industry I worked in. Just a comment.