[WTB] EE Student (Europe) looking for semi-decent function generator  - Page 1
Forum section: electronics / general

author: belzrebuth
author_rank: Frequent Contributor
timestamp: March 01, 2018, 03:54:18 pm
content: Hi all,I'm an Electrical Engineering student (first year since it's my second degree) and I've already have set up a basic bench (tek analog scope, hakko station, a brymen multimeter, farnell bench psu etc) but the only thing that I'm really missing is a function generator that's decent enough to help me understand/troubleshoot mostly analog audio circuits but can also work as a clock source for logic circuits.I need it to be clean, stable and reasonably accurate frequency-wise.I'm located in Greece so I'm looking for EU offers only!I considered getting a Rigol DG1022/DG1022Z but at that cost I'd be better getting a DS1054Z and leave the f-gen for later.I like that those rigol models are 2-channel but they're a little outside of my budget right now.I need something cheaper to fill that gap and maybe upgrade later.I'm open to suggestions/offers!Thanks:)

author: DC1MC
author_rank: Super Contributor
timestamp: March 01, 2018, 04:46:46 pm
content: FeelTech FY6600 is an option, look up the megathread in the forum and start reading from the endCheers,DC1MC

author: rhb
author_rank: Super Contributor
timestamp: March 01, 2018, 04:51:27 pm
content: Read the JDS6600 and FY6600 threads. There are spectrum analyzer plots for the FY6600 around pages 12-14 of that thread. Not sure about the JDS6600 thread.Both units have PS issues because of the SMPS without proper grounding. That's pretty easy to fix. The FeelTech has a serious FW problem, but we appear to be closing in on having a FOSS FW stack for that. Mine borked itself the day after I fixed the PS issue by adding a 3 wire plug.I see that one of the conspirators has appeared while I was typing.

author: belzrebuth
author_rank: Frequent Contributor
timestamp: March 01, 2018, 05:26:50 pm
content: I don't like these at all.They seem pretty useful but pretty cheaply built for my liking.I'd prefer a newer Rigol or an older reputable branded unit.Thanks though..!

author: Mr. Scram
author_rank: Super Contributor
timestamp: March 01, 2018, 05:28:54 pm
content: Quote from: belzrebuth on March 01, 2018, 05:26:50 pmWhat is your budget? Your wishes will have to depend on the budget.

author: belzrebuth
author_rank: Frequent Contributor
timestamp: March 01, 2018, 05:34:20 pm
content: You're right; I did not mention my budget!My budget is around 200-250€ for a used genearator but that's the ceiling.For around 400 I'd go with the Rigol or equivalent new unit.The reason I don't want to spend that much for a f-gen is that I don't own a DSO yet which is around that price.

author: Mr. Scram
author_rank: Super Contributor
timestamp: March 01, 2018, 05:48:21 pm
content: Quote from: belzrebuth on March 01, 2018, 05:34:20 pmIs a function generator enough? The models you mention are AWGs. If a simpler function generator is good enough, your budget should be plenty to find something nice.

author: belzrebuth
author_rank: Frequent Contributor
timestamp: March 01, 2018, 06:00:32 pm
content: Arbitrary waveform might be too much for me now.But who knows if I might need it later.For simpler signal gens do you have anything in mind?Remember I'm in EU so older HP models while cheap in the US are not an option since shipping + import taxes cost usually more than the unit itself!

author: corn11
author_rank: Regular Contributor
timestamp: March 01, 2018, 06:06:50 pm
content: With a bit of patience you're may be able to find a HP/Agilent 33120A (15 MHz 40 MSa/s) in that price range. I've bought mine back then for ~250€ in a proper condition (a little bit of cleaning was necessary). On paper the 33120A may look a bit dated (with respect to memory depth and sample rate) but it is reliable and has specs you can count on, a proper firmware, a good documentation (service manual with schematics available) and a floating output.

author: belzrebuth
author_rank: Frequent Contributor
timestamp: March 01, 2018, 06:11:51 pm
content: Yes the 33120A looks nice but a little hard to find.I may have to save for a dual channel Rigol if I don't find something on eBay or here..

author: Mr. Scram
author_rank: Super Contributor
timestamp: March 01, 2018, 06:32:47 pm
content: Quote from: belzrebuth on March 01, 2018, 06:00:32 pmYou may want to shoot TopLoser a message about an AWG or DSO. He may have something that just suits your budget.

author: rhb
author_rank: Super Contributor
timestamp: March 01, 2018, 06:34:17 pm
content: The reason I suggested the JDS and FY units is the sine wave output is remarkably free of harmonics. Older analog function generators are not as good.An MCU and an AD9851 board from eBay will get you a good sine wave. But by the time you put it all in a box it will cost as much as the JDS or FY units. Yeah, they have issues, but all are fixable. The price goes up rapidly from there which is the reason that a bunch of old guys are working so hard on the FeelTech. It's got all those lovely BNCs on the back panel and the signal quality is quite good.For audio work, a good soundcard will be sufficient and for generating clocks almost any MCU dev board will do. There are lots of MCU dev boards with audio codecs that run to 96 KS/S.Back when I was in grad school and all I had was a 5 MHz recurrent sweep Heathkit scope my signal sources were some oscillators I built on perf board using op amps. There is a denumerably infinite supply of function generator designs available.If your focus is audio, read "Max Wein, Mr. Hewlett and a Rainy Sunday Afternoon" by Jim Williams. A soundcard and some MATLAB code will let you measure THD to whatever accuracy you desire. In any case you should read the article.As much as anything, engineering is an attitude and experience. IMHO you should try building a function generator or two before you buy one.

author: belzrebuth
author_rank: Frequent Contributor
timestamp: March 01, 2018, 06:56:17 pm
content: Thanks for the info!I'll definitely read that article.I've already put together a XR2206 function generator kit and the AD9851 function generator with an arduino.I use the AD9851 as a clock with my digital circuits.It's nice that goes down to 1Hz ( need to see those leds blinking! )I also use my laptop with MultiInstrument and an external audio interface that has enough amplitude on the output.A nice well built bench instrument would be nicer though.Often times I've considered getting a frequency counter too but I think a DSO will solve that problem.I sometimes repair synthesizers and other audio equipment so a frequency counter is often handy but I use a software spectrum analyser intended for audio to get by.Nice tip on the THD meter too.I'll look into it.Thanks again:)

author: rhb
author_rank: Super Contributor
timestamp: March 01, 2018, 10:14:00 pm
content: I highly recommend anything written by Jim Williams, Bob Pease and Bob Widlar. Or anything about them. They were absolutely amazing.With a modern PC and souncard you can exceed the measurement limits of the HP distortion analyzer Jim used, but you'll need to learn a bunch of DSP tricks to do it. However, it's not hard and the education makes it well worth while.