Best bang for the buck entry Oscilliscope

I wanted to get some first glances on the practical communication between my Raspberry Pi and a Sensor connected by I2C. I did not need a high sample rate and also didn't want to pay that much. So I did what every cheap electrical engineering student did and searched for some scopes on AliExpress.
After some research I found the so called Hantek 6022BE. It did cost almost €50 and even had fast shipping to Germany. Thus, I bought it.

After it arrived I was pleasantly surprised by the build quality and started to play with it. There are two channels in total, which are more than enough for beginners. The communication is using USB2 which is not that great. USB3 would be a more logical choice if you ask me. The price difference can't be that large for different USB protocols. There also exits a rectangular test Signal which can be used to calibrate the probes which are two in total and have an acceptable quality in this price range. Besides the USB 2 connectors also some strange ports exits (USBXI???). That's all for connectivity.

Taking apart the Hantek Scope is pretty straight forward. You just need to loosen 4 Philips heads screws on the side of the channel inputs and the board can be pulled from the case. Inside the scope is primarily a USB2 Controller and an EEPROM. Besides that also some empty spots exits, where components of higher specs would be placed. Remarkably there is even a heat sink on a not-identfifyable component. Furthermore, the grounding is greatly implemented by using the sides of the PCB to ground everything to the aluminum case. In a nutshell a great internal structure for such a generous price.

The original software was kinda awful, so I looked for alternatives. I found one pretty quick. There exists a OpenSource project called OpenHantek which uses open and free drivers and is just way better than the original crappy pile of garbage Hantek programmed.
After some time I noticed that the program had an Option for an AC Coupling Mod. AC coupling is a Hardware implemented analog filter which suppresses DC voltages. The program even included the guide for performing this modification. In short terms, a Capacitor and some smaller Components needed to be added to the circuit. I ordered the items from Ali and after some time the fun could begin:

The following parts and tools are needed for the mod (see full details here):

The Capacitors need to be connected in series between the channel signal output and the onboard resistor R17 on the first and resistor R27 on the second channel. Also, the PhotoMOS ICs need to be connected in series to the Cap while Pin 3 is directly connected to the resistors and pin 4 is connected to the channel input alongside with the new 1 kΩ resistors. Pin 2 of both PhotoMOS need to be grounded.

And the last pin, which is pin 2, is connected to the Jumper Pins (J4) alongside with the 220 Ω Pulls-Up resistors.
This circuit uses the 100 nF caps to filter out frequencies in the low spectrum. Thus, DC terms will be terminated and ripples in DC voltage can be measured much easier. The PhotoMOS is needed to switch between DC and AC Coupling. The OpenHantek will then use these normally unused jumper pins to switch modes by changing the voltage on these pins.
I would recommend this product to everyone who wants a great beginner scope or just analyzes low frequencies. The Sample Rate of only 48 MSa/s (30 MSa/s in OpenHantek) is very low and cant be used for any high frequency application. But for example automotive circuit should work just fine with the 6022BE. I recommend everyone who wants to look at high frequencies scopes with at least 500 MSa/s or even 1 GSa/s. These are of course a lot more expensive and need more space because of the build-in screen and controls.

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