the art of automata: Circuits

Here are some pictures of the different circuits used in my automata.
This one has on the right the infrared detection part, the 28-pin chip at the bottom center is the Atmega microcontroller, the two 8-pin chips are UCC27424 MOSFET drivers used to drive the DC motors. The left part provides a 40 kHz square signal to the ultrasonic transmitter, it is made of NE556 double timer and a CD4049 hex inverter. The idea was to turn on and off every 50 to 500 msec with the second timer of NE556 the 40 kHz signal provided by the first timer to use pseudorange. This turned out not to give a satisfying accuracy and I finally relied on an extra RF signal to synchronize US transmitter an receiver.

There is two power supplies, the first one at 6 V for the IR and the motors, the second one at 12 V to be added to the previous 6 V to get the required 18 V for driving the US piezoelectric crystal. The PCB below is slightly different, only one 5 V regulator is used both for the Atmega and for the IR. Also the secondary circuit of the NE556 has been removed. Ultimately I replaced NE556 by NE555.