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Introduction

Digital Metronome Planning A1: I am going to make an electronic metronome device which produces equally spaced sound at a variable speed which is displayed in beats per minute. A2: The system consists of several sub-systems. The basis of the system is the two astable oscillators. One oscillator is variable between frequencies of around 40-300 Hz by the use of a potentiometer and the other has a fixed frequency of 1Hz. The outputs of the two oscillators are put into the inputs of an AND gate and the output of the AND gate is used to drive a counter. The counter is linked to a decoder and a 7 segment display. The terminal count output of the counter is connected to the clock input of a second counter which is also linked to a decoder and a display and a third counter is also linked in this way. This sub-system thus produces a 3 digit visual output showing the frequency in Hertz of the variable astable oscillator. The output of the variable astable is also take to a series of counters and logic gates which divide the frequency of the output of the oscillator by 60 which gives an output of the same frequency in beats per minute as the frequency of the variable astable in Hertz (pulses per second). ...read more.

Middle

2. The metronome must operate at speeds of 40 - 300 beats per minute 3. The system must have a display output showing the speed of the metronome in beats per minute accurate to + 10% A6: Instead of using seven segment displays to show the speed, I could have used a different display system such as an LCD display. An LCD display would be capable of showing the same information as he seven segment displays and would possibly look much neater. The reasons I decided to use seven segment displays over and LCD display are: 1. Although the system would take up less space on its own, it may end up using more space on the board than the seven segment displays as it could possibly need a lot of decoders. 2. Also I understand how seven segment displays work but I do not know anything about the workings of an LCD display so the use of it would require a lot of research ad I would be more likely to make mistakes hen using it. A8: A9: Resistors I have used the following resistors in my circuit: * 4.7K? for the timing mechanism of the oscillators * 1.2K? for protecting the 7 segment displays * 100? to protect the LED and the rest pin of the counters in my frequency divide by 60 sub-system * All resistors have a tolerance of + ...read more.

Conclusion

circuit and also taken readings from the 3 digit display to see how these match up to the actual frequencies of the pulse. The frequencies appear to match up to a certain degree of accuracy so the circuit works as it was intended. C3: My circuit worked as I intended which was for it to be an "electronic metronome device which produces equally spaced sounds at a variable speed which is displayed in beats per minute". I have also met all of my original objectives: 1. The circuit must work with a 9v + 1v power supply so that it is able to operate with a 9 volt battery as well as a power supply. All tests were conducted using a power supply on a 9 volt setting and the circuit worked as required. 2. The metronome must operate at speeds of 40 - 300 beats per minute As shown in the tests above the metronome operates at speeds of 6 to 308 beats per minute. 3. The system must have a display output showing the speed of the metronome in beats per minute accurate to + 10% As shown in the tests above the display shows a reading which is within 10% of the speed of the metronome beats. C4: As the circuit worked as desired, there was no need to make any improvements to its workings. ?? ?? ?? ?? Adam Arstall ...read more.

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