The Chinese clone to the XR2206 works exactly like the geuine EXAR chip. Even the typical glitches in the sine-wave look the same. The limitation to 12 V suppy voltage is probably due to smaller chip strcutrures, so breakdown voltages of the seiconductors are much lower.

For circuits, where the space on the breabboard is insufficient, all connections to the tubes and the other parts are available at the screw-terminals and at the 2mm banana-sockets on the sides of the PCB. All the suggested circuits in the manual can be build on the small breadboard!

Yes. Usually to 1°C where 10°C would be totally sufficient.

I don´t where these did originally come from. But if you search for RJ45 strip-/crimp-/ tools, you will find many brands.

@@KainkaLabs Thank you for the information. I will search for that information

That is one of many misconceptions about Germanium-diodes used in crystal-radio receivers. In fact it´s the ratio between the forward and the reverse current at very low voltages (below 100 mV!) that determins the usability of diodes in crystal radio circuits. If you really needed 300 mV to hear AM-stations, you could only hear very near stations. Because of the much lower reverse current of Schottky diodes they are far superior to every Germanium diode. And in fact the first crystal-radio rectifier diodes (the real "Crystal-diodes") where a small wire (Cat´s whisker) was contacted to a Galena-crystal, were in fact Schottky-diodes!

Well, not in your IPhone and other high-end products also manufactured in China :-)

Don´t know. Get the EEVBLOG 121GW. The best multimeter ever, but not the cheapest.

For that purpose we have our "LCR-Box": www.ak-modul-bus.de/stat/rlc_box_standard_lcr_box1.html www.ak-modul-bus.de/stat/universelle_rlc_box_deluxe_lcr_box2.html The purpose for the reference capacitor box is to check multimeters and RLC-meters. So 6 values (+ 100 pF cap single) with 1% accuracy (or measured to 1% for the larger values) is quite adequate to the tast, I think :-)

The kit includes all the extra parts I described in the video. But the chip is of course the "12V-limited" Chinese clone.

@@KainkaLabs SO the easiest way is just to buy Chinese set DIY and change all components locally accordingly to your design. Do you think for beginner in electronics such generator in audio frequencies up to 20 kHz sin square can be sufficient as test signal source? Paying hundreds € for semi pro unit seems to be over-investment in my case. BY the way - I see comments that original EXAR is obsoleted already by manufacturer so risk to buy fake element is high today. Thanks and Happy New Year.

Yes, this is a good beginners project. And for a basic check of audio amplifiers it is totally sufficient. The "hardest" signal for an audio amplifier is the triangle signal which is quite clean with the XR2206. Triangle signals have a lot of harmonics and the sharp change of the slope at the upper and lower edge . So if an amplifiert reproduces a 1 kHz triangle waveform correctly at it´s output it is OK. For frequencies above 1 kHz you have to change to the sine signal because audio amplifiers are usually bandwidth limited and cannot reproduce the higher harmonics of a 10 kHz triangle or square waverform. For checking or minimizing THD (if there is a trimmer for that) you need a completely different setup. Either with a soundcard and some audio-analyzer software. The soundcard can output very clean sine signals with very low distortion and the soundcard-inputs are also very good even with "only" the standard 16 bit resolution. Or you need an ultra-low distortion (<<0,1%) audio signal generator and signal-analyzer. Very expensive. Or you take a modern DSO with 12 bit resolution and let the FFT function do the analysis. Siglent and Rigol have these for very competitive prices nowadays. But the soundcard + analyzer-software is still the best and cheapest solution. And the Chinese XR2206 clone is functionally and from it´s performance 100% identical to the genuine EXAR chip. The only difference is the maximum supply voiltage of 12 Volt. The original EXAR-chips are nearly unobtainium nowadays because production was stopped many decades ago. You may get them for high prices on EBay (around 20$ upwards)

@@KainkaLabs Thank yo so much for so comprehensive answer. Danke Schoen and Happy New Year.

@@KainkaLabs One more clarification. In your improved manual is written R2/R7 pots to be changed to 10K and R2 also changed to logaritmic. R7 remains linear right ?

You probably mean "Nu-Trol". Of course there are many alternatives (especially on the US market). But for cleaning potentiometers or sliders I would only use the chemicals I recommended in the video. The resistive carbon layer is extremely sensitive and irreplacable when damaged mechanically or by the wrond "solvent"/"cleaner".

@KainkaLabs thx for the good advice.

That is how a sinus out of an XR2206 looks like. Also with the geuine EXAR chip.The sine-wave is generated from a triangle-wave with a diode-network.

Sorry, but you didn´t get the point :-) When I switch the DSO from DC to AC-coupling, I only made this to let the DSO calculate the AC-coupled RMS-value for comparing it to the two AC-coupled multimeters. This is to demonstrate that 1.) an AC-coupled multimeter can never give a correct RMS reading for a voltage with a DC-offset and 2.) even the AC-coupled RMS-value is often off because of bandwidth limitation of the multimeter in case on non-sinusoidal voltages (here: the UNI-T mutimeter)

No, you didn´t get it. When you place the desolder-tip on the solder, you want to get the maximum "suck" and not a slowly increasing vacuum. Otherwise it´s hard to suck solder out of through-plated holes with the wire or pin still in the hole. Often the clearing between a componetn wire or an IC-pin in the hole ist only of the order of 1/10 mm.

It´s simply a 1.8 mH inductor.

Varactor-diodes are used since around the 1970s as replacement for variable capacitors. But you have to use a special circuit-topology to block the DC tuning-voltage from the rest of the circit. And you need a variable DC voltage-source up to 30V for tuning. So it´s still easier using a variable capacitor, but they are not so flexible and small as varactors.

@@KainkaLabs well i will check this one from yours then, do you have a video of it tunning a Loop antenna ?

A frame antenna is of course a loop-antenna. But it´s a multi-turn loop and it is used not in short-circuit mode.