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This is a very simple design of digital oscilloscope. The original project comes from EP 8/2004. The only difference I've made was adding RS232 to USB converter to use it with my laptop. Schematic can by found here: analogue and digital.

TDA8703 digital oscilloscope 1

Main board:

There can be seen analogue input section with OPA2350 amplifiers and relays as voltage dividers. ADC is fast television IC, TDA8703. Digital data goes through DS89C420, via USB to PC application showing results.

TDA8703 digital oscilloscope 2

On the other side we can see lots of addicional tuning SMD components. Making the analogue section work properly was a really hard work, especially with a variety of input frequencies, amplitudes and shapes.

TDA8703 digital oscilloscope 3

USB board:

It is harder and harder to find RS232 connector in modern computers. That's why I decided to make this converter. I doubt there is at least one computer without USB. Schematic of USB section can be found here.

FT232BM 1

Another adventage of this board is a place for separate power supply as the device can't be powered from USB plug. My aim was to separate it from the computer, that's why the USB interface is optoisolated.

FT232BM 2


The case is a standars steel box. The same was used in my generator project.

TDA8703 digital oscilloscope 4

PC application:

The original author of this oscilloscope and author of this application is MKEiA. Here are some screens showing all this working. The input signal is from MAX038 generator.


1kHz - square


1kHz - sin


1kHz - triangle


100kHz - square


100kHz - sin


100kHz - triangle



Overview | Main Board | USB | Case | PC


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