games timer 2

Posted on Feb 4, 2014

Circuits using large value resistor/capacitor combinations are not very accurate because of the wide tolerance and leakage current of polarised capacitors. A better solution is to use an astable circuit together with a binary counter/divider chain which reduces the frequency of the astable pulses. The 4060 cmos integrated circuit is ideal for the games timer application. In this

games timer 2
Click here to download the full size of the above Circuit.

session, you will investigate how to set up the counter/display subsystem of the games timer using another cmos integrated circuit, the 4017 decade counter. To find out about the 4017, you need a source of pulses. You could use the 4060 astable circuit investigated in the previous session, but it is more convenient to build a temporary alternative circuit. About the easiest way of building an astable is using a special type of NAND gate, called a Schmitt trigger NAND gate. Here are the symbols for normal and Schmitt trigger gates: The Schmitt trigger gate has two different thresholds. If the voltage applied to one of the inputs to the gate starts at 0V and is slowly increased, the logic 1 threshold, when the input starts to count as a HIGH voltage, is around two-thirds of the power supply voltage, that is, about 6V with a 9V supply. On the other hand, if the voltage connected to the input starts at 9V and is slowly decreased, the logic 0 threshold, when the input counts as a LOW voltage, is around one-third of the power supply voltage, or about 3V. This difference in thresholds allows you to use a Schmitt trigger gate as the basis for an extremely simple astable circuit. The 4017 is a divide-by-10, or decade counter, with 10 individual outputs which go HIGH in turn when pulses are fed to its CLOCK input. The connection details for the 4017 are: To make the 4017 work, you need to connect the power supply pins (`beasties`...

Leave Comment

characters left:

Related Circuits

  • New Circuits



    Popular Circuits

    The Simplest Car Battery Charger
    2 watt Stereo audio amplifier
    Auto-Phone dialer for alarm security system
    10 Note Sound Synthesizer Circuit
    Making an Ikea Mood Lamp Beyond All Repair
    Video IF circuit TV Schematic Diagram
    pic LM032
    Off Line Telephone Tester
    designing a phantom antenna power supply system
    Bob Beck Electrifier
    Adjustable DC power supply circuit
    Simple 100W inverter schematic design