Anyone use GW Instek analog function generators ? - Page 1
Forum section: electronics / testgear

author: Franz Zinn
author_rank: Contributor
timestamp: May 24, 2013, 05:53:43 pm
content: Hi,I wonder if anyone has used GW Instek GFG-8200 series analog function generators (for instance GFG-8215A) ? If so could you kindly share your views on the instrument. The are quite inexpensive and easily available (for instance from rapidonline) are they worth it ?regardsfranz

author: Hydrawerk
author_rank: Super Contributor
timestamp: May 24, 2013, 10:38:32 pm
content: How stable is the frequency?

author: JimmyMz
author_rank: Regular Contributor
timestamp: May 25, 2013, 01:43:03 am
content: I like this topic because I've been wondering the same thing as you Franz. I noticed that ~$75 is the going rate on flea bay, so they do look quite attractive compared to some of the other overpriced offerings at the same website. I look forward to a solid answer to this topic.

author: MasterOfNone
author_rank: Regular Contributor
timestamp: May 25, 2013, 01:24:09 pm
content: I have a Matrix MFG-8216B function generator and I believe this is the same as the GW Instek GFG-8216A except the Matrix has an additional 4W amplifier built-in for driving a speaker.I believe all the rebadged MFG/CFG-8xxxAmodels are the same as the equivalent MFG/CFG-8xxxB, except the 8xxxB has the extra build-in Amplifier.I also believe the other ranges like the 8000H and 8000G are completely different to the 8000A.As expected the function generators is pretty easy to use. On my unit the frequency knob is a 5 turn potentiometer (pot) so I can set the frequency reasonably accurately (I don’t think the 8215 has a 5 turn pot). If you get one that has the 7 Segment LED Frequency display, then you’ll notice that the frequency you set drifts slightly, that’s because the function generator has a built in Frequency counter that can be set to read the internal Frequency or an External Frequency. So this means the unit shows what frequency you are actually getting rather than what it thinks it should be generating (Not bad).I just did a simple test and on my unit the Frequency drifts around 0.2% after 2 hours (at 3KHz). If drift this is too high maybe a low end DDS function generator or AWG would be better. Even the low end AWG’s definitely offer a lot more functionality, but there is a price difference so I’ll not go into this.On my Generator there’s a separate output for 5V-TTL or 5v-15V CMOS but no 3.3V, but on the 50Ohm output you can add a DC offset and set the amplitude, so this isn’t a problem.Actually if you set the output to the maximum amplitude and add a DC offset you can get the output to clip, but the generator soft clips the waveform so it is less likely to cause damage to your circuit.Also all the knobs are pots (rather than rotory-encoders) so your last setting will be remembered after you power off. However the buttons are momentary switches and the generator doesn’t have any built in memory for the buttons, after a power-on it just defaults to 1K Range and Triangle waveform, so you’ll need to set these each time, but it’s only a couple of button presses (so no major problems there).When you turn the knobs to adjust the DC offset and Duty Cycle nothing happens, this is because you have to pull the knob out before you rotate it. This may seem like a crap idea at first, but it means you can get back to 50% Duty Cycle or equal positive and negative peaks by just pushing the knobs back in ( with the knobs in any position), not a bad idea.As for quality build. I purchased my Matrix branded unit a few years ago directly from China using Ebay, and even before I opened the parcel I knew something was wrong, because I could hear a rattling sound. It had a loose daughter board flopping around inside. I opened the unit, screwed the board down and everything was fine. I was actually surprised that the build quality was actually very good, it was just that on my unit the board wasn’t screwed down. Maybe the GW Instek branded units wont suffer from this type of QA issue, but even with the QA problem I was thinking the unit was very good value for money, a easy to use and quiet, basic function generator.

author: JimmyMz
author_rank: Regular Contributor
timestamp: May 25, 2013, 10:14:19 pm
content: Quote from: MasterOfNone on May 25, 2013, 01:24:09 pmThank you for taking the time to write this post. It sounds like a nifty unit for a little more than basic functionality, and that is probably appealing to a few folks who would like to experiment with different waveforms. One reality that's holding me back on making an analog function generator purchase is the low cost AWG's by Rigol/Siglent, and how much more they offer for twice the amount of money. I also find myself questioning if I'll ever get into audio (amplifiers, etc...) where this product is truly useful. I wonder if some techs on this forum, who inject signals for troubleshooting devices, can respond to what their opinion is on one of these older analog function generators, in comparison with say the Siglent SDG1020 or equivalent. Is an analog function generator your current tool to inject signals? Would you buy an old Tektronix CFG function generator for $125 or go with a Siglent SDG1020? Thanks guys