Function generator - need a jungle guide:-) - Page 1
Forum section: electronics / beginners

author: FriedMule
author_rank: Frequent Contributor
timestamp: October 27, 2019, 02:31:30 pm
content: I have seen everything from a 2MHz to 2,000$ functions generator and 500MHz and 3GHZ, I have also seen 30$ 25MHz and then there is also types like the arbitrary Siglent's 499$ 40MHz (120MHz).I can imagine that a Agilent or Keysight 25MHZ has to be better then a 30$ or maybe even better then the Siglent?What I need right now is properly not an arbitrary and I can't imagine what I need 100MHz fore and I do also not need a NASA grade signal.But on the other hand, do I want a signal generator I can relay upon, one where if I say 5MHz square wave, then do I get a square wave and not something that may be called a square wave if you close one eye. :-) I do have a great 10MHZ frequency standard, so that part is also not important.In other word want to be sure, that I get out what I ask fore, no question asked!My problem is not to find models out there, my problem is to read / understand what one datapoint means for me contra an other from an other specsheet.Do any of you know of new / used models?

author: capt bullshot
author_rank: Super Contributor
timestamp: October 27, 2019, 04:09:52 pm
content: Quote from: FriedMule on October 27, 2019, 02:31:30 pmThat would be the HP33120A model - the first function generator I've encountered in my life as an engineer that did put out what I dialed in. Never used the arbitrary part of it. IMO only topped off by the modern Keysight / Tektronix / Siglent models.Performance wise (just puts out what you dial in) most of the cheap $25 ones from ebay should achieve this today, though the overall quality (including and especially the user interface) of a brand name one will be better, but for example Keysight and Siglent will be quite equal quality wise. The cheap ones will have more or less serious restrictions, e.g. regarding the output voltage range, output noise level, nasty user interface, ...

author: RoGeorge
author_rank: Super Contributor
timestamp: October 27, 2019, 04:14:59 pm
content: Here's your requested jungle guide:Would help a lot if you would saywhy/what fordo you need a generator.On short, many classifications were made:- analog or digital generators, by the way the signal is generated- audio or RF generators, by the range of the output frequency- arbitrary (AWG) or functions (usually only a few well known waveforms, like triangle, saw, sinus, square, PWM) generators, by the possible waveform shape- modulated/unmodulated/noise generators and so on, many other classifications can be done.

author: FriedMule
author_rank: Frequent Contributor
timestamp: October 27, 2019, 04:30:09 pm
content: Quote from: capt bullshot on October 27, 2019, 04:09:52 pmYes you may be right in that most generators can produce the diferent signals today:-) But I think they may also make a lot extra... a sinus wave with 10th harmonic or something:-) Ill look at yor sugestion.Quote from: RoGeorge on October 27, 2019, 04:14:59 pmOh what I want to use it for... I think non digital and non RF projects in the next 10-20 years:-)A good all-round unit, if I later need something special, I'd have to look again.Ofcause more funtions give more to work with, but I am mostly looking after a workhorse to most minor tasks where I know I get clean correct signals.Any idea on how many money to trow at the unit for DIY?

author: capt bullshot
author_rank: Super Contributor
timestamp: October 27, 2019, 04:50:03 pm
content: Quote from: FriedMule on October 27, 2019, 04:30:09 pmYou might get lucky with an unit like this one (just an example):https://www.ebay.de/itm/254355461027Which would be a decent analog general purpose function generator of a well known brand

author: rstofer
author_rank: Super Contributor
timestamp: October 27, 2019, 05:13:45 pm
content: Quote from: FriedMule on October 27, 2019, 04:30:09 pmThe Siglent SDG2082X that I bought can add harmonics. In fact, you may be able to find the Valentine's Day Heart thread where a 40 MHz version was used to generate a heart pattern through the clever use of harmonics. That project led to my buying the 80 MHz version. Works well!QuoteYou can shop around for the Siglent models. Here is what Amazon has to say:https://www.amazon.com/SDG2082X-Function-Arbitrary-Waveform-Generator/dp/B0181ZAALOI went for 80 MHz because I could, not because I will ever use it. In fact, I doubt that I will ever use it beyond 10 MHz. Note also that even though the sine wave reaches 80 MHz, the square wave maxes out at 25 MHz. Read the datasheet on whatever device you choose.25 MHz is ok for me because it is unlikely I will use it up to even 1 MHz. When I do fast logic, it is inside an FPGA with its own 100 MHz clock. Even if I wire-wrapped a Z80 project, it is unlikely it would run at over 6 MHz.Read the User Manual before deciding. Look at how you can form waveforms with harmonics. Look at how the UI works, compare features among brands.While you're at it, read the User Manual section for the Analog Discovery 2 Waveform Generator and then see if ANY commercial unit can come anywhere close in terms of features. Yes, bandwidth is limited but I'm not sure that it really matters.https://reference.digilentinc.com/learn/instrumentation/tutorials/ad2-waveform-generator/startHands down, the AD2 is the best investment in test equipment on the planet. You can download the Waveforms software and play with the Demo gadget to see how things work. One thing I just tried with the Demo gadget is to generate the following equation:sin(2*PI*X) + 0.1*random()Just adding a little noise to a sine wave - pretty cool.I know everybody just giggles when they see the AD2. They have no idea what they're missing out on.

author: FriedMule
author_rank: Frequent Contributor
timestamp: October 27, 2019, 06:18:33 pm
content: Thanks guys! Sorry for my apparent reluctants in this comment but a unit like Siglent with a mountain of features, nice GUI, 2ch and what not for nearly nothing... Do that unit really work? To get a GUI, one ch and less MHz in an Agilent, you have to pay maybe about 6x that price. Just asking because when tings seems to good, they normally are:-)

author: bd139
author_rank: Super Contributor
timestamp: October 27, 2019, 06:26:18 pm
content: Go mid range. Rigol DG1022Z 25Mhz unit. Crack it to 60Mhz. Decent RF performance as well. Better than Siglent. Better than the Agilent ones.But it’s not going to last 10-20 years. 5-8 years I reckon.HP 3310A, HP 3312A and TTi TG210 if you want something that will last. All are 20 years old or more.33120A is ok but expensive for what it is, noisy and has a very failure prone unobtanium display.

author: FriedMule
author_rank: Frequent Contributor
timestamp: October 27, 2019, 06:34:04 pm
content: Quote from: bd139 on October 27, 2019, 06:26:18 pmTo that price do I think I can afford a new unit after 5-8 years, not if it was 6x the price:-)Oh 33120A do not sound so fantastic any longer!So you can really get something that works for that money?!

author: GerryR
author_rank: Frequent Contributor
timestamp: October 27, 2019, 06:37:46 pm
content: I had, and sold, an HP33120; very nice 15 Mhz AWG. I now have a BK Precision 20 MHz AWG (4045), which I got for a really good price on Ebay. Very easy to use and good customer support. BK makes really nice equipment, all be it, a little pricey, but if you watch for bargains, you can get some good deals. I would stay away from the Chi 6600, 6800, etc, unless you don't mind hacking them to get some reasonable performance from them. Just my $0.02.

author: bd139
author_rank: Super Contributor
timestamp: October 27, 2019, 06:42:21 pm
content: Yes I’m going to kick the 33120A while it is down now. 33120A I certainly wouldn’t recommend now explicitly. No output on/off switch, some of the parts are unobtainable, noisy fan, horrid menu system, only 15Mhz, single output. Only good but is the output is floating. They go for 2/3 of the price of a new Rigol unit here which is insane.New keysight ones I’m no fan of. Might as well go Rigol and Siglent now. It’s all same made in China stuff. Warranty is the same. Keysight service is the same now (replace entire unit or major assemblies).

author: rstofer
author_rank: Super Contributor
timestamp: October 27, 2019, 07:08:28 pm
content: Quote from: FriedMule on October 27, 2019, 06:18:33 pmThe Siglent SDS2082X certainly works but, at over $600, it better. I seriously think the 2042 is completely adequate even though it is only 40 MHz. It's about $100 cheaper.I just don't see the purpose in higher frequencies any more than I see the utility in 30V 5A PSUs. It just doesn't come up for my projects.Here's the project:https://www.eevblog.com/forum/chat/a-valentine_s-day-activity-for-your-scope-and-function-generator/msg1143021/#msg1143021If a competing waveform generator won't allow all of these harmonics/phases, it is off the list of candidates. In my view...With DSP, it is fairly easy, and inexpensive, to create waveform generators. FPGAs are all over the place! This is a lot different than 20 or 25 years ago when the systems were fairly complex because they were likely to have a lot more discrete components.

author: FriedMule
author_rank: Frequent Contributor
timestamp: October 27, 2019, 07:11:58 pm
content: so if I understand right, the 33120A is a bit like some computers were in "the good old days" fine for it's time and maybe still okay, until something goes wrong, then where you just screwed?Yes everything is mostly made in China now, even most of the "Made in USA", they should write "made in USA, of parts from China"About hacking, no problem in my book, I have bought the unit, it's mine and how I use / abuse my property is my decision:-)But what model gives most after tinkering? I mean in signal quality and frequency?The Rigol did go to 60MHz.

author: rstofer
author_rank: Super Contributor
timestamp: October 27, 2019, 07:56:33 pm
content: Quote from: FriedMule on October 27, 2019, 07:11:58 pmIn the first place, the 33120A is a single channel generator. Most of the more modern AWGs will have two channels. That's kind of a big deal. I can't do the Valentine Heart with only one channel. Among other things...I BRIEFLY looked at the User Manual and I didn't see a way to add the 3rd, 5th, 7th, 9th and 11th harmonics to a fundamental sine wave. Maybe I missed it. The maximum harmonic frequency still has to fit inside the bandwidth so for a Siglent 60 MHz unit, so a 5 MHz signal is all we can use as a fundamental if we really need the 11th harmonic. Everything has limitsThe 33120A has 10 internal waveforms, the SDG2082X has 196 internal arbitrary waveformsOn its best day, the 33120A isn't any significant fraction of the Siglent with the possible exception that it has lower harmonic distortion. Then again, it has much lower bandwidth.I'm not going to do it but I suspect an Excel spreadsheet of specifications might be interesting.I don't know why we're not including the Siglent SDG1000 series AWGs. They are considerably cheaper but, of course, they won't have the features of the SDS2000 series. The only one I can really talk about is the SDG2082X because it is on my bench. Again, the buyer needs to compare the specs.There is also the SDG800 series that is even cheaper.Tautech needs to weigh in here. This thread rightly belongs in the Test Equipment forum where the TEA people can weigh in.

author: tautech
author_rank: Super Contributor
timestamp: October 27, 2019, 08:29:27 pm
content: I'm here.The key here is signal purity and for general sig gen use it doesn't matter too much as 14 bit AWG's are fine for lots of requirements.SDG1032X is your cheapest entry level 2ch AWG and the feature set is much the same as the 16 bit SDG2000X models.Both SDG1032X and SDG2042X can be hacked to max BW's for their ranges.SDG1000X models do square wave to their max BW's while most other brands and models limit square wave BW to some figure much lower than their sine wave spec.I have all the Siglent AWG models and could pick any one but the SDG1032X is what lives on my bench as it perfectly meets my current needs.If I need to venture into the RF world I drag out my SSG3021X hacked to the 3.2 GHz model.

author: FriedMule
author_rank: Frequent Contributor
timestamp: October 27, 2019, 10:10:36 pm
content: Quote from: rstofer on October 27, 2019, 07:56:33 pmYes I can easily imagine times where 2 channels would be handy.Quote from: rstofer on October 27, 2019, 07:56:33 pmHmm it has to be able to do it, it's an abritary. :-)I am thinking on audio where 10th harmonic would be nice to create, but that is way below what the generator can handle.Quote from: rstofer on October 27, 2019, 07:56:33 pmWOW what a differance, yes and they are probberly with about the same performance... old proudly made vs new Chinese.Quote from: rstofer on October 27, 2019, 07:56:33 pmI am just surprised that you can get so much for so little, there has to be a chats:-)Quote from: rstofer on October 27, 2019, 07:56:33 pmIt may be great, but then it had to be of several models and types.Quote from: rstofer on October 27, 2019, 07:56:33 pmNo but maybe it is because the price difference is not that great while the benefits are?Quote from: rstofer on October 27, 2019, 07:56:33 pmHmm yes but it looks like it is a model if you cant afford other "real" generators:-)Quote from: rstofer on October 27, 2019, 07:56:33 pmAnd he did!!! :-)

author: tautech
author_rank: Super Contributor
timestamp: October 27, 2019, 10:38:36 pm
content: Quote from: FriedMule on October 27, 2019, 10:10:36 pmOnly the max BW and 14 bit vs 16 bit.....and touch screen on SDG2000X and SDG6000X modelsPlease notice the distinction between 1000 series and 1000X series:https://int.siglent.com/products-overview/sdg1000/The 5000 and 1000 models are being phased out in favor of the more capable and modern X models.

author: FriedMule
author_rank: Frequent Contributor
timestamp: October 27, 2019, 10:44:30 pm
content: Quote from: tautech on October 27, 2019, 08:29:27 pmGreat, thanks for being here!!SDG2042X looks like it can be a 120MHz! And 16bit sounds wary nice, I can see many models from DIY beginner to NASA gone wild:-)Now where the DIY units is cheap-ish, is there any reason for going for anything less then the 2000 series?Quote from: tautech on October 27, 2019, 08:29:27 pmIs that not an spectrum analyzer?

author: tautech
author_rank: Super Contributor
timestamp: October 27, 2019, 11:01:28 pm
content: Quote from: FriedMule on October 27, 2019, 10:44:30 pmOnly if the relative signal purity a 16 bit sig gen offers isn't required.Only you can decide on exactly what your needs are and might be.Also consider what DSO you have as some can capture a waveform and then import and recreate it with the AWG.Not everyone considers this a necessary feature and yet others love it.Also, if you have one of the Siglent DSO's that can do Bode plot any of the Siglent AWG's can interface seamlessly with the DSO to provide the signal source for Bode plot.Quote from: FriedMule on October 27, 2019, 10:44:30 pmNope, RF gen:https://int.siglent.com/products-overview/ssg3000x/