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# Telephone account using a calculator and cob principle

2016-02-15 05:25
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This article describes a telephone account using a calculator and cob principle. In order to better grasp the principle of combining text, please understand this schematic. Before use, check its suitability by applying solid 1.5 v DC side between C and D, as shown. Then check the DC voltage terminals A and B; these terminals on a clock which is connected to a coil. If you stick in good condition, the multimeter needle will move forward and backward once per second. In fact, the 0.5 Hz clock in the terminal A and B, phase difference of 90 o. The advantage is that it works with this stick in a 1.5 v DC source.Clock pulses from the terminal A and B can be combined with a bridge, including diodes D1 to D4, get 1 Hz clock pulses. These clock pulses are applied to the base of transistor T1. The collector and emitter of transistor T1 is connected to the calculator '=' terminals. The formation of an equivalent number of pulses may be determined from the most recent call to the telephone directory. However, the pulse repetition frequency (PR) found in the directory can not be directly used in this circuit. Compatibility with this circuit, the pulse rate applicable to a specific place / distance, based on time of day / holiday into a pulse rate equivalent to (pre-) using the formula PRE = 1 / PR. You can prepare a variety of pulse rate look-up table and their equivalents (see Table). Suppose you want to make the call in pulse rate 4 STDs. From the table to write down the pulse rate, pulse rate is equivalent to 4, which is 0.25. Note that in the mature a telephone in a telephone exchange, a call immediately switched telephone account, it advances will further increase the pulse rate. Therefore, a call should be included in the calculation of calls. To make calls in pulse rate 4, slide switch S1 to 'off' (pulse setting position) and press the calculator button in the following order: 1, " ", 0.25, "=." Here, 1 is the most preliminary statistics, and 0.25 is PRE. Now the calculator display 1.025. Called meter is now ready to count. Call now, if called mature, immediately slide switch S1 '' (start / standby position). Corn begins to generate clock pulses of 1 Hz. Once per second transistor T1, so "=" button to activate the electronic calculator is once per second. Calculator display
Start from 1.25 per second advance is as follows:
1.25,1.5,1.75,2.00,2.25,2.50 so on.

 LookUp Table Pulse rate (PR) 2 2.5 3 4 6 8 12 16 24 32 36 48 Pulse rate eqlt. (PRE) 0.5000 0.4000 0.333 0.250 0.166 0.125 0.083 0.062 0.041 0.031 0.027 0.020 Note : Here PRE is shown up to three decimal places. In practice, one may use up to five or six decimal places.

Telephone call meter using calculator & COB

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