Overview
The circuit provides a means of repetitively alerting an individual jogger for a fixed amount of time that employs beeping as the indicator.
Terminology
- 4093 – a quad 2-input NAND with Schmitt trigger inputs integrated circuit, generally characterized by small fluctuation in voltage supply, very high impedance, outputs that can sink and source, one output can drive up to 50 inputs, high speed gate propagation time, high frequency, and low power consumption
- 4060 – a 14-bit ripple counter with internal oscillator that has glitches which may occur in any logic gate systems connected to its outputs due to the slight delay before the later counter outputs respond to a clock pulse
- 4017 – a decade counter where the count advances as the clock input becomes high that may be combined with diodes for some functions such as flash sequences
- BC337 – a small signal NPN Silicon AF medium power transistor used for general purpose switching and amplifying applications with features such as TO-18 manufactured package, suited for AF driver stages and low power output stages, and divided into three group types
- Piezo Buzzer – a type of buzzer that can function as a speaker with piezoelectric disk attached where a mechanical oscillation of the piezoelectric diaphragm is damped properly to provide a wider frequency band of the sound pressure
Circuit Explanation
The circuit works as a timer that is capable of sending out beeps in an interval of one, two, three minutes or as desired by the user for jogging purposes. The use of 1 pole 9 ways rotary switch SW1 is to choose the predetermined time or interval when the Piezo buzzer will provide sound or beep. Each pole represents the number of minutes for the buzzer to beep three times. Pole 1 represents one minute while pole 2 represents two minutes, and so on until the maximum 9 minutes is reached.
Only one switch at a time should be used on the device to avoid being damaged. Instead of a rotary switch, a DIP switch can also be used. If the jogger will require a one time set, a hard-wired link can also replace the rotary switch. After a preset delay of time, the frequency of beeping can be altered by changing the value of resistor R4 from 10 K Ohms to 15K Ohms, where the beeps can be more or less than three times.
There is a way wherein only a one-second beep can be obtained which involves disconnecting Pin 9 of IC1C from Pin 9 of IC2 and connecting it to Pin 8 of IC1C. The device may be powered by a 3 V battery which can be in the form of two 1.5 V AA or AAA batteries in series.
Application
The timer circuit is designed not only for joggers but also for brisk walkers as they set the timing of their exercise since some people are very conscious on their health and would like to follow a program which involves time they will start and finish. The concept of this circuit is now being employed in ipods and other music playing device that are clipped on the individual’s arm or shirt during their exercise.
Schematic
Part List
Source:redcircuits.com/Page32.htm
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