Abstract: A circuit for producing musical tones is disclosed which includes a keyboard for selecting the musical tones, and a tone generator responsive to the keyboard for generating a square wave signal having the frequency of the musical note to be generated. A charging circuit is provided for charging a capacitor to a predetermined level of voltage when the square wave signal is terminated, and for exponentially discharging the capacitor when the square wave signal is initiated. A modulation circuit amplitude modulates the square wave signal in proportion to the capacitor voltage to produce an exponentially decaying signal which simulates the waveform produced by a struck piano string. A speaker is also included to convert the exponentially decaying signal into audible musical tones having the sound of piano notes. The circuit of the invention requires only a small number of components, making it suitable for use in miniature musical toys.

Abstract: An electronic guessing game is disclosed which includes a keyboard for entering numbers, and a light and speaker for producing a variety of visual and audible signals. A prize is also provided within a transparent housing. A first player enters a secret number by means of the keyboard. A second player then enters his guess at the secret number using the same keyboard. The second player attempts to retrieve the prize by reaching into the transparent housing. The position of the players hand is detected by a group of photocells. If the player's guess is not equal to the secret number, the game will generate an error signal and the player must withdraw his hand. The closer the player's guess is to the secret number the closer he may approach the prize before the error signal is sounded. If the player guesses the secret number within a preallotted time interval, he may retrieve the prize. A mode of operation is also disclosed in which the game chooses the secret number by means of a random number generator.

Abstract: A music synthesizer is disclosed which includes a keyboard for entering musical notes to be synthesized into the music synthesizer. The music synthesizer also includes a rhythm control arrangement, such as push buttons, for selecting prestored repetitive rhythm pattern tempos to be synthesized into the music synthesizer. A single microprocessor computer is provided which processes and establishes priority of signals from the keyboard and the rhythm control buttons for generating signals indicative of the frequency and amplitude of the musical note to be synthesized and for generating musical instrument signals and combining them into the rhythm pattern to be synthesized. A tone generator is provided which is controlled by the computer for generating a squarewave signal having the frequency of the musical note to be synthesized.