EEVblog Electronics Community Forum
Products => Test Equipment => Topic started by: alin_im on April 21, 2015, 04:14:01 pm
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hey guys,
i recently find a signal generator on ebay that blow my mind... http://www.ebay.co.uk/itm/12MHz-Dual-channel-Arbitrary-Waveform-DDS-Function-Signal-Generator-FY3212S-/281537690313?pt=LH_DefaultDomain_3&hash=item418cf43ac9.. (http://www.ebay.co.uk/itm/12MHz-Dual-channel-Arbitrary-Waveform-DDS-Function-Signal-Generator-FY3212S-/281537690313?pt=LH_DefaultDomain_3&hash=item418cf43ac9..) it is only 80 pounds what is the catch ??? i know it is Chinese but it dose a lot of things for its price. Is it worth it for this price or is just a knock off ? I will be using for basic stuff nothing too fancy, i am a student at the moment but i think it will help me for the next 3 - 4 years. Any how, what are your thoughts ? i Attached you the manual that they send me.
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If you keep your eyes peeled on gumtree and eBay you can pick up better brand units.
I picked up a Thandar TG550 for £60/on Gumtree last year. There was one with a TTi triple DC supply both for £100 the other day too. Probably £800 retail.
I tend not to trust anything like that unless its under £20 inc delivery.
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The price seems to be plausible, considering the shortcomings when compared to the well known low-end function generators:
1) Only 12 bits amplitude resolution - that would have been high-end some 20 years ago, but nowadays 14 bits is quite common.
2) Only 2048 samples per waveform.
3) Very high distortions, which was to expect after the observations mentioned above. Sine wave distortion of 0.8% at 1kHz is even worse than most analog function generators, which used diode networks to form a sinewave from the triangle of an RC-oscillator. On the topic of triangle waves, the FY32xxS produces one up to 6MHz, but linearity is only specified up to 10kHz and is quite bad, even at these low frequencies.
4) No modulation capabilities.
5) Very simplistic user interface & display.
If you can live with these limitations, it might be worth buying.
Yet I think you are better off saving a few bucks more and getting a Siglent SDG805 or SDG810.
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At 12 bits vertical res I'd expect a THD more in the range of ~-70 dB (~0.03 %). 0.8 % is very poor and worse than ... anything?
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I have a similar unit, but with the FY2105S.
No complaints. It doesnt have the quality and features of a 2000 dollar unit, but then again, it isn't ;)
It delivers a decent signal in my opinion. The only thing i had to remove was the beeping sound it makes with every interaction.
If you're looking for a cheap signal generator, i'd say these units are worth it.