If a prototype needs to be built physically, and an MT8870 isn't available, these ICs can be used as drop-in replacements in many circuit designs:

Excessive real-time processing of high-frequency analog audio signals.

If you are connecting the MT8870 to an Arduino to read the digits, use the following logic. Assuming Q1-Q4 are connected to Arduino pins 3, 4, 5, 6.

Third-party interactive models can sometimes trigger unexpected errors in the SPICE simulation engine. Component Not Found Error