Quick look at: A cheap DIY function generator kit

Introduction

I recently bought some cheap electronic DIY kits from amazon, just because I wanted to improve my soldering skills. One of them was a cheap function generator based on the XR2206-IC. The complete kit with an enclosure costs about 14€ and it can be bought here. If you find a cheaper one let me know in the comments below and I’ll update the article!

Building and soldering

I initially planned to make a film on this one, but I ran out of space and the video stopped halfway through. So unfortunately there is no video material of me building it.

However I can tell you, that some of the pads on the PCB were rather hard to solder. When I design PCBs I tend to make the pads rather large, because I find it more convenient to solder components on larger pads. However it was possible, though I can’t recommend this kit to absolute beginners.

Building the case was a bit hard, because these tiny laser cut plastic parts tend to fall apart easily. But the hardest thing here was to get the protective film off the parts. Afterwards you just have to put the shorter screws through the four mounting holes on the PCB and tighten them up with nuts from the other side. These just act as spacers so the board stands evenly in the case. Afterwards you just put the case together and close it up with the longer screws in the corners.

The finished product should look like this:

function-gen-finished
Figure 1: The finished product

I really like the looks of it. It’s compact and makes a solid impression.

How to use it

You select the range of the frequency and the waveform with jumpers. The little pins are labelled on the case:

function-gen-markings
Figure 2: Labels on the case

As you can see I had troubles removing the protective film on the insides of some of the numbers, like the zeros. If you have a lot of patience you could remove them with a tiny pin or something.

However you select the frequency range with a jumper and you can then alter the frequency with the two potentiometers on the right. The one on the left changes the amplitude of the wave.

The waveform is then output via the screw terminals on the right.

Measuring the accuracy

Now to the most important part: Is it accurate? Does it even work? Let’s find out. Unfortunately the device doesn’t come with a display or something that tells the user what the frequency should be, so you’ll need an external device to tune it to the correct frequency.

So I’ll measure if the range is as labelled and if the waveform stays the same over time.

I’ll end this quickly: Unfortunately mine didn’t work at all. It just refused to generate me any waveforms at all. Luckily they packaged the schematics of the device with it, so it’s possible to troubleshoot it. I checked all the connections and everything was placed and soldered correctly, so I can just assume that the IC doesn’t work. I guess that’s due to the bad packaging of the IC. It came without any ESD protection at all.

Conclusion

Should you buy it?
Well mine didn’t work, but it was sure fun to build it and it gave me an hour of fun (even tough it took me 30 minutes to peel off the protection of the case material). However I’d still say: Yes. Buy it and give it a try if you’re looking for such a device. I’ve bought several kits online recently and they all worked, except for this one. But you can always send it back for free, which I’ll do.

Unfortunately I can’t tell you right now whether the device accurate or not, but I’ll re order this kit, create a short video of the building process and then I’ll hopefully be able to test it’s accuracy.

Further readings

Sparkfun – XR2206 Datasheet
Amazon – Buy the kit here

Disclaimer

As usual none of the products mentioned in this article were sponsored, so this article is 100% neutral and it represents my opinion. All provided links to shops give me no benefit.

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