Showing posts with label counter. Show all posts
Showing posts with label counter. Show all posts
Monday, September 30, 2013
AFX Slot Car Lap Counter
AFX slot car sets are very enjoyable but you can increase the fun with a lap counter. This circuit will count from 00 to 99, with independent counters for each track. The sensing device used is a Hall effect sensor (UGN3503; available from Dick Smith Electronics). One of these sensors is glued under a section of each track (printed side up); between the slot and one of the track rails is the best spot. In this position, it will allow the ground effects magnets on the cars to pass over them. The sensor will provide a voltage of about 3V when a car passes over it and about 2V without a magnetic field. Both counter circuits are identical, with dual op amp IC5 handling the signals from both sensors.
IC5a and IC5b are wired as comparators, with a 2.5V reference derived from zener diode ZD1 via the 10kO and 12kO resistors. Each time the output of IC5a goes high it clocks IC1a, a 4518 BCD counter. NAND gates IC2a & IC2b provide a carry out to the other half of IC1 for a 2-digit display. More counters may be cascaded this way to provide extra digits. The BCD outputs of IC1 drive 7-segment decoders IC3 & IC4 which drive common cathode LED displays. Push-button S1 resets the counters to 00 for both tracks for the start of a new race.
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IC5a and IC5b are wired as comparators, with a 2.5V reference derived from zener diode ZD1 via the 10kO and 12kO resistors. Each time the output of IC5a goes high it clocks IC1a, a 4518 BCD counter. NAND gates IC2a & IC2b provide a carry out to the other half of IC1 for a 2-digit display. More counters may be cascaded this way to provide extra digits. The BCD outputs of IC1 drive 7-segment decoders IC3 & IC4 which drive common cathode LED displays. Push-button S1 resets the counters to 00 for both tracks for the start of a new race.
Saturday, April 6, 2013
Counter Down Timer Circuit
This circuit is design of the counter timer that using countdown calculation. This circuit is using 555 IC as main control. 555 IC is a counter IC and a transistor switch to activate a relay either ON/OFF (mode selected by a jumper) as soon as the counting period is over. The circuit consists of an oscillator, a ripple counter and two switching transistors. This is the figure of the project circuit.
The 555 is configured in the standard astable oscillator circuit designed to give a square wave cycle at a period of around 1 cycle/sec. The output pulse from pin 3 of the 555 is fed to the clock input pin 10 of the 14-stage binary ripple counter, the 4020 (or 14020.) Operation of the circuit is explained in next. In this circuit C3, R4 and D1 are arranged as a power-on reset. When power is applied to the circuit C3 is in a discharged state so pin 11 will be pulled high. C3 will quickly charge via R4 and the level at pin 11 falls thus enabling the counter. The 14020 then counts clock pulses until the selected counter output goes high. D1 provides a discharge path for C3 when the power is disconnected. You can change the components values of R1 and C1 to set the 555 count frequency to more than 1.0 Hz. If you change the count to 10 seconds then a maximum timer delay of 81920 seconds, or 22.7 hours, can be obtained.
The output from the 4020 goes to a transistor switch arrangement. Two BC547 are connected so that either switching option for the relay is available. A jumper sets the option. The relay can turn ON when power and counting start then turn OFF after the count period, or it can do the opposite. The relay will turn ON after the end of the count period and stay on so long as power is supplied to the circuit. Note that the reset pin of the 555 is connected to the collector of Q1. This enables the 555 during the counting as the collector of Q1 is pulled low.
The 555 is configured in the standard astable oscillator circuit designed to give a square wave cycle at a period of around 1 cycle/sec. The output pulse from pin 3 of the 555 is fed to the clock input pin 10 of the 14-stage binary ripple counter, the 4020 (or 14020.) Operation of the circuit is explained in next. In this circuit C3, R4 and D1 are arranged as a power-on reset. When power is applied to the circuit C3 is in a discharged state so pin 11 will be pulled high. C3 will quickly charge via R4 and the level at pin 11 falls thus enabling the counter. The 14020 then counts clock pulses until the selected counter output goes high. D1 provides a discharge path for C3 when the power is disconnected. You can change the components values of R1 and C1 to set the 555 count frequency to more than 1.0 Hz. If you change the count to 10 seconds then a maximum timer delay of 81920 seconds, or 22.7 hours, can be obtained.
The output from the 4020 goes to a transistor switch arrangement. Two BC547 are connected so that either switching option for the relay is available. A jumper sets the option. The relay can turn ON when power and counting start then turn OFF after the count period, or it can do the opposite. The relay will turn ON after the end of the count period and stay on so long as power is supplied to the circuit. Note that the reset pin of the 555 is connected to the collector of Q1. This enables the 555 during the counting as the collector of Q1 is pulled low.
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