You will receive one bare PCB. The populated images are for illustrative purposes only.

What is it?

On this PCB can be soldered analog front-end, which together with a cheap USB audio card can be used as PC oscilloscope for observation a signals in the audio band. Together wit Arduino or ST32 microcontroller it can cover wider frequency band and greater voltage range.

Why did you make it?

At home I have some cheap USB sound cards, which can be bought in Aliexpress, Ebay or other global online shops for a less then 1.5 USD. I was wondering what interesting I can use them for and decided to try to make an low frequency PC scope with one of them. In Internet I have found a nice software, which can be used as USB oscilloscope and signal generator. I did some reverse design of the card (described in the first step) and decided that if I want to have fully functioning scope - I need also to design an Analog front-end, which is required for the proper voltage scaling and shifting of the input signal applied at the microphone input of the audio card, because the microphone inputs expects maximal input voltages in the order of few decades of millivolts.

What makes it special?

It is simple but it is able to work in 3 modes:

• AC
• DC
• ground

Its input range also can be switched between 3 voltage division ratios-

• 100:1
• 10:1
• 1:1

These ranges can be changed under desire. The front-end circuit has also linear adjustment of the input signal offset.