Cheap beginer's signal generator - Page 1
Forum section: electronics / general

author: dr_p
author_rank: Frequent Contributor
timestamp: October 29, 2012, 08:06:15 am
content: My first post among EEEVers, so Hi there everybody!I'm feeling the need for a waveform generator, mostly for experimenting/understanding filters, pwm, audio and general micro-controller related stuff. I have a very small work bench, so the equipement has to be very small, but usable (lcd, enough buttons etc.). Also, I tend to favor the looks of modern LCDs, rather than old school huge dials.I sawthis DDS generatorand looks interesting. It's ~60$ shipped worldwide, also oneBay.Problem is it's low-res 8 bit DAC and slow sample rate of 2.5MS/s. This means max 200Khz sine and 10KHz other (triangle, staircase, ramp, square). I think it's too low even for a beginner's needs.What do you think of this unit? For the price, of course.Cheers!

author: ProBang
author_rank: Contributor
timestamp: October 29, 2012, 09:39:34 pm
content: The link doesn't work...

author: johnboxall
author_rank: Unknown
timestamp: October 30, 2012, 12:13:43 am
content: I have one of these unassembled around here somewhere. On a quiet day (ha) I'll put it together and demo it. In the meanwhile:Original link -http://www.jyetech.com/Products/085/e08503.phpUS -https://www.sparkfun.com/products/11394Australia -http://littlebirdelectronics.com/products/frequency-generator-kit-fg085

author: andyturk
author_rank: Frequent Contributor
timestamp: November 01, 2012, 03:05:42 pm
content: I bought one of the kits from Sparkfun and put it together last week. Here's a short review: The functionality it offers isn't bad for $50, but the software is a real letdown: it crashes regularly. You're better of putting that $50 towards a real function generator.Depending on what order in which you touch the buttons, the FG085 will simply lock up. On my device, pressing the "OFS" key to change the dc offset makes the device unresponsive. It's expecting input, but none of the keys work. When this happens, wiggling the rotary encoder sometimes works as does powering the device on while holding down various keys. A similar issue appears on the JYETech bulletin board and it's described as a hardware issue, but it sure feels like a software problem. There's a newer firmware version than what came with my kit, but I don't have the appropriate hardware to program the device and I don't want to spend more effort getting it to work.The hardware design is cheap, but functional. When you build the kit, you have to be very careful to align the 21 switches exactly the right way. They'll go into the board two ways, but only one is correct. There are no orientation marks on either the board or the switches, but the switch casings are asymmetrical if you know what to look for. They're also through-hole parts with no pin tension to hold them in the board while you solder. I ended up taping each one separately. It was a tedious assembly.One of the electrolytic caps near the power supply warms up noticeably within seconds after applying power. It makes me wonder how long it'll last. The corners of the acrylic faceplates are very sharp and not pleasant to hold. Filing them off is easy though.Bottom line: I think the concept of a $50 function generator was good. However, the kit is easy to assemble incorrectly (i.e., get one of the switches in backwards) and the software is unreliable.

author: dr_p
author_rank: Frequent Contributor
timestamp: November 05, 2012, 07:39:12 am
content: Thank you for this hands-on review. I might look for a classic waveform generator. There seem to be some available in the 50-100$ area. New or not.

author: G7PSK
author_rank: Super Contributor
timestamp: November 06, 2012, 06:38:38 pm
content: I bought one of these units. I cant fault at the moment as it has served my needs to date.http://www.ebay.co.uk/itm/190649700756?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2649

author: brainwash
author_rank: Frequent Contributor
timestamp: November 08, 2012, 09:34:04 pm
content: The item description is just funny:Quote

author: JuKu
author_rank: Frequent Contributor
timestamp: November 09, 2012, 06:48:26 am
content: Quote from: dr_p on October 29, 2012, 08:06:15 amIf those specs are enough for you, you are not looking beyond the audio band. Software can be found for free, and you probably already have an audio card...