In the ‘Wire Loop Game’, a test of dexterity, the player has to pass a metal hoop along a twisted piece of wire without letting the hoop touch the wire. Usually all the associated electronics does is ring a bell to indicate when the player has lost. The version described here has a few extra features to make things a bit more exciting, adding a time limit to the game and a ticking sound during play.
Two 555 timer ICs are used to provide these functions. IC1 is configured as a monostable which controls the time allowed for the game, adjustable using potentiometer P1. IC2 is a multivibrator to provide the ticking and Two 555 timer ICs are used to provide these functions. IC1 is configured as a monostable which controls the time allowed for the game, adjustable using potentiometer P1. IC2 is a multivibrator to provide the ticking and he continuous buzz that indicates when the player has touched the wire with the hoop.
Wire Loop Game Circuit Diagram
When the monostable is in its steady state, the output of IC1 (pin 3) is low. T1 acts as an inverter, and D2 is thus forward biased. R8 and R4 are therefore effectively in parallel, with the result that IC2 produces a low audible tone. The value of R4 is considerably greater than that of R8, and so the frequency of the buzz generated by IC2 is chiefly deter-mined by the value of R8.
When the monostable is triggered, the high level at the output of IC1 is again inverted by T1. D2 is reverse biased and so R8 is effectively removed from the circuit. The frequency of IC2 is now largely determined by the value of R4. The ratio of R4 to R5 and the value of C4 affect the mark and space periods for the multivibrator: for a satisfactory ticking sound short pulses with long gaps between work well.
Whether a sound is produced also depends on the voltage on pin 4 of IC2. When the 9 V supply is connected the monostable is initially inactive and there is no voltage across C1. Pin 4 (reset) on IC2 is thus low and no tone is produced. IC1 is activated by a brief press of S1, which generates a low-going trigger signal on pin 2 to start the game. C1 now charges via D1 and IC2 is allowed to oscillate, generating the ticking sound.
The pulse width of the monostable sets the game duration, and can be adjusted using P1. If the allowed time expires, or if the reset input to IC1 is taken low (which happens when the hoop touches the wire), the monostable returns to the quiescent state. This causes IC2 to generate the low buzz sound. D1 is now reverse biased and C1 discharges through the relatively high-valued resistor R9. After a few seconds the voltage across C1 falls sufficiently that the buzz stops and the circuit is ready for the next player.
The circuit can be built first on a breadboard, so that the component values can easily be changed to suit particular preferences for game duration and buzz pitch. When suitable values have been selected the circuit can be built more permanently on a printed circuit board. The author used a sheet of plywood to form a base for the game, the twisted wire being fixed to the board and wired to the electronics mounted below it.