The circuit presented is a game based on an integrated TTL of type 7473. In the figure we have a "soccer lottery" that draws 1 of 3 possible guesses, which are indicated by the lighting of 3 LEDs. The base of the circuit is a double flip-flop of the JK type. In this circuit the clock is provided by the oscillator with an integrated 555 that operates at a frequency high enough that the player has no influence on the count and, therefore, on the result. Random pulses are applied to the double flip-flop when pressing S1. When we release, the draw position, or the LED on, will depend on the number of pulses counted. Changes in the circuit can be made in the sense that the transistors excite SCRs and, thus, lamps connected to the power supply. A problem that can occur in a project involving an optical sensor, such as a phototransistor, is how to directly excite a port with this component.
