Page 100 - Robots Androids and Animatrons : 12 Incredible Projects You Can Build
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It is not necessary to remove the 7448 and 7-segment display. The
8870 chip has sufficient output to drive both the 7448 and 4028.
The digital display is pretty handy when checking the output from
the 4028. For the sake of simplicity, Fig. 5.26 just shows the 4028
connected to the 8870.
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5.25 Schematic of front end of IR DTMF receiver
5.26 Schematic of DTMF receiver with BCD-to-decimal converter
Team LRN Sensors
