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7/28/2019 Circuit Contador en Reversa l

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Circuit drawing of Digital dial


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Pattern drawing of Digital dial(Wiring side)

Circuit explanationof Digital dial

Rotary encoder

This time, the encoder which I used is EC16B which is made by the

ALPS electricity company in Japan.

The encoder has three terminals, and one is allocated for common

terminal (COM) and the other two are a terminal for the output.The output terminal becomes the condition whether or not whichconnects with the common terminal or whether or not it is not.

Two terminals for the output differ in the timing which touches acommon terminal when the axis of the encoder is turned.

The output relation in case of EC16B becomes like the followingfigure.


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The standard data of EC16B

Pulses/Rotation 24

Output code Phase difference 2 signals

Rotational angle 360 degrees

Mounting method Fastened with bushing nut

Ratings 5V DC, 0.5mA

Maximum operating curent 0.5mA

Insulation resistance 50V DC, 10M-ohm min

Withstand voltage 50V AC

Sliding noise

t : Masking time to avoid chatteringWhen R = 100K-ohm, t = 5msec

V1 = V2 = 1V max

Chattering prevention circuit

The circuit this time is using capacitor(C) toprevent from the chattering.

The chattering is the phenomenon whichrepeats slight time ON, OFF when the switch

connects.

This is the phenomenon which comes out whenusing a mechanical switch. The electronic

circuits has detected ON, OFF of this short time

and sometimes malfunctions. When not using

the chattering prevention circuit, more than onecount sometimes rises in spite of being only one count.


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It is using Schmidt trigger-type inverter (7414) to arrange a waveform.

In the Schmidt trigger-type inverter, the circuit which is called " the Darlington connection" is used.This is the circuit which connects a collector at the pre-stage with the base at the following stage

directly. The output turning-over of the inverter becomes high-speed with this way.

Data sheet for 74HC14

Up Down detection circuit

It is the circuit which judges whether it is a CW ora CCW compared with two pieces of output from

the encoder.It used D-type flip-flop (7474) for the judgement.

The D-type flip-flop makes the operation to outputthe output terminal (Q) in the condition of the D

input terminal when the clock(CK) changes intothe H condition from the L condition.

Operation by the clockwise(CW) is explained.

When the A point changes into H from the L, the

clock (CK) of ICB changes into H from the L andICB becomes the condition to take in D input.

However, at this point, the B point is in the L

condition and the clear terminal of ICB is in the L

condition. Therefore, the output (the Y point) of

ICB keeps an L condition. Because the clearterminal is always an L when the clock (the Apoint) of ICB becomes H from the L in the CW, the

condition of ICB doesn't change.Next, the B point changes into H from the L. This

changes the clock (CK) of the ICA from the L to Hand the ICA becomes the condition to take in D

input. The output (the X point) of the ICA changesinto H from the L because the A point becomes H

condition already at this point and a clearedcondition is already canceled.

An ICA is initialized by the clear terminal of theICA and the output (the X point) of the ICA changes into the L from H when the turn moves ahead

and the A point changes into the L from H.When moving an encoder to the right in 1 click like above explanation, one pulse is output on the X

point. In case of CW, the pulse doesn't develop on the side of the Y point. The pulse occurs to the Xpoint every time it clicks to the right.

It works like the CW in case of CCW, too. In case of the CCW, because the B point changes into Hfrom the L earlier than the A point, the pulse doesn't develop on the side of the X point. The pulse

occurs to the Y point every time it clicks to the left.

By above operation, it does the judgement of the CW, the CCW and the pulse occurs to each output

terminal every time it clicks.
http://www.hobby-elec.org/e_datasheet.htm#74hc14http://www.hobby-elec.org/e_ckt10_6.htmhttp://www.hobby-elec.org/e_ckt10_6.htmhttp://www.hobby-elec.org/e_datasheet.htm#74hc14


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BCD counter

The BCD is the abbreviation of Binary Coded Decimal. It is the counter which returns to 0 in the

next pulse with the count rising from 0 to 9.It used 74192 for the counter. There are input for addition (UP) and input for subtraction (DOWN) in

this counter. As for the output from the up down judgment circuit, it inputs a pulse in case of CW toUP and it inputs a pulse in case of CCW to DOWN.

It makes a clear terminal H condition with the capacitor and the resistor to make display zero in case

of the turning on.At the circuit to introduce this time, it is a 1-

digit counter, but 74192 has the terminal of

carry and the terminal of borrow, too, and it

is possible to more than one digit count.


LED driver

It is the driver to drive an LED for the digit present in 7 segments.

It drives each device in 7 segments by the input of BDC.

The relation between BDC and each device in 7 segments is as follows.

No.BDC code 7 segments

D C B A a b c d e f g

0 0 0 0 0

1 0 0 0 1

2 0 0 1 0

3 0 0 1 1

4 0 1 0 0

5 0 1 0 1

6 0 1 1 0

7 0 1 1 1

8 1 0 0 0
http://www.hobby-elec.org/e_datasheet.htm#74hc74http://www.hobby-elec.org/e_datasheet.htm#74hc192http://www.hobby-elec.org/e_datasheet.htm#74hc74http://www.hobby-elec.org/e_datasheet.htm#74hc192


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9 1 0 0 1

mark : ON.

mark : 7447 is OFF and 74247 is ON.

Data sheet for SN74LS247

7 segments LED

It uses an LED for the digit display which used 7 segments (seven devices).

Because there is various size, use liked one. But, when using with the circuit this time, use an anodecommon type.

Two kinds are in the LED in 7 segments. They are an anode common and a cathode common.

The anode common is the one where the terminal which adds positive voltage becomes common. Asfor the LED driver which is using this time, the side of the negative (the grounding) becomes

common. Because it is, the anode common must be used.

The resistors for the electric current control of the LED must be put every each segment. The numberof the lighting LED devices depends on the figure to display. When putting a resistor in the common

part, the light of the LED has changed every figure to display.
http://www.hobby-elec.org/e_datasheet.htm#74ls247http://www.hobby-elec.org/e_datasheet.htm#74ls247

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