I ordered a few chips from China cheap. The seller indicated that it is the original MSI chip. I modelled the circuit twice, one in the project I need it for, another on breadboard. So far all the chips I got refuse to work. Output is just noise that doesn’t change, not even in regards to input.
I told the seller that now I’m getting the same chip from the reputable source and if it works I will be starting a dispute, to which seller immediately replied that they are happy to refund everything. But I want to be sure this is not me doing something wrong. So how do you tell it is a fake?
I'm just an amateur in this accord but I used a cheap wave form generator and an o-scope built from a kit to see the effects of band-pass filters for a clock radio I made.
Isn't an equalizer just a series of adjustable band filters?
Could you do something similar here?
Right, as I suspected. Pin 8 is used to set internal oscillator, if this oscillator is not working, then nothing is going to work. I did put oscilloscope on pin 8 on my chip and nothing. Now I found this that pretty much confirms my suspicion
Did you connect a resistor and a capacitor (C 33 pF, R 200 kohms) according to the datasheet diagram? If you are not, there is no way the chip generator can work. My chips are also ordered from Aliexpress and works.
Yes, and you can do something similar with bandpass filters (they aren't adjustable in a spectrum analyzer) but that's a LOT more complicated.
The MSGEQ7 is pretty-slick little chip that makes the hardware and/or software super simple (when it works).
The MSGEQ7 datasheet says, "Seven Band Graphic Equalizer" but that's NOT what it is... It's a chip for making a 7-band spectrum analyzer which could be built-into a graphic equalizer.
I can’t say I didn’t know about the possibility of getting fakes, but I knew I would get refund if this was the case. And I did. Just before this I got a cheap Cirrus Logic ADC chip from China and made custom ADC and it was as good as the one I bought from the US, which was made in China too. It is just that MSGEQ7 is quite specific chip, popular among Arduino enthusiasts, so some Chinese entrepreneur thought they could copy the design and flog it.
I doubt it - a lot of fakes are rejects or seconds - still work but don't meet datasheet specifications (takes some sophisticated testgear to determine this). If it was the genuine part you need to be aware of a common trick - the first time you order you get the goods, subsequent times its a fake or substitute part of lower value - this plagues manufacturers who have to quality audit every batch made.
So here is follow up. Bought microchip from Mouser, shipped from Texas, was gonna get it Monday but it came this morning so I greeted FedEx guy in my underwear.
The markings on genuine chip are just like in the video, 3 lines with indent. I tested oscillator on pin 8, and guess what, it works!
Congratulations. By the way, I'm curious if anyone has tried to change the frequency of the generator? Thus, it should change the seven frequencies of the spectrum analyzer MSGEQ7. So with 2 chips with different frequencies might become a 14 frequency analyzer. Or with just 1 chip and dynamic change to scan different frequencies maybe. I did a similar test years ago but I don't remember what the result was.
For another project I used MKR ZERO, ADC via I2S, and Arm FFT library for 2x16 and 1x32 spectrum analyser. But that before I knew MSGEQ7 existed. Seems like a good solution for a project based on Nano Every. Don’t really need more than 7 per channel.
Yes changing the oscillator frequency will shift the bands.
However these switch mode filters are only second order filters so if you slot another channel between them then there is quite an overlap in the response and these new channels will be more of a mixture of the two channels above and below what you are looking at.
