In the CD4094 data are synchronized on the rising edge and the LCD display will take on the falling edge shows us that this signal can be shared.

Well, then at the rising edge CD4094 transfers the data of the new byte out and fall on the side of the LCD display reads. Keep in mind that this method can not read LCD information display.

Now comes the hard part: How to separate text commands. LCD has a pin for this: RS pin. When this command for 0 accepted, as accepted in a text (ASCII characters). How do you solve this?

Before sending a character to initialize a timer on CD4094 500uSec. The resistor R1 will load capacitor C5. Then send the character to the CD4094 as quickly as possible. Thus, the capacitor simply does not have enough time to discharge. The LCD display will accept it as text. In order to command is the same, only in reverse. The capacitor has to be discharge.

Emitter follower T1 formed to protect the network R / C. The reason for this is that the LCD RS input is a TTL input signal and we put it to work quite well.

Program C Language

#include <hidef.h>
#include "derivative.h"

#define LINE1    0x80
#define LINE2    0xC0

#define DTASHT   0x01     // PTA0
#define CLKSHT   0x02     // PTA1
#define STBSHT   0x04     // PTA2

#define CTRL     1
#define DATA     0

void Shift(char, char);
void Delay(int);
void Write(char, char*);
void Init_Dsp(void);

void main(void) {

CONFIG1 = 0x01;
CONFIG2 = 0x00;

DDRA    = 0x07;
PTA     = 0x00;

Init_Dsp();

for(;;) {
Init_Dsp();
Write(LINE1,"  Hola Mundo    ");
}
}

//=====================================

void Init_Dsp(void) {
PTA |= CLKSHT;
Shift(CTRL,0x06);
Shift(CTRL,0x0E);
Shift(CTRL,0x38);
Shift(CTRL,0x80);
Shift(CTRL,0x0C);     // Cursor off
Shift(CTRL,0x01);     // Clear Display
}

void Write(char pos, char *text) {
Shift(CTRL,pos);
while(*text) Shift(DATA,*text++);
}

void Shift(char donde, char dato) {
int i;

for(i=0; i<8; i++){
if(dato & 0x80) PTA |=  DTASHT;
else            PTA &= ~DTASHT;

if(donde) {
PTA &= ~CLKSHT;
Delay(200);
PTA |=  CLKSHT;
}
else {
PTA &= ~CLKSHT;
PTA |=  CLKSHT;
}
dato <<= 1;
}
PTA |=  STBSHT;
PTA &= ~STBSHT;
if(donde) Delay(2000);
}

void Delay(int time) {
for(; time>0; time--);
}

As seen in the IR Wireless Headphone schematic, transmitter circuit is very simple here. The transformer assembled as a matching impedance, and low impedance windings are connected in parallel with the TV or radio speaker. IR diodes are commonly used. 10 ohm resistor that limits the current through the IR diode should be 1 mg. This 9Vdc powered transmitter that can be provided either by regular batteries or AC / DC adapter.

As the receiver is concerned, the same infrared light captured by the phototransistor, it is pre-amplified and amplified by transistors BC549C and then gives enough power to move the speaker of headset through the output transistor.

This receiver, like the transmitter is also powered from 9Vdc, but in this case must inevitably be provided by the battery, because with AC / DC adapter all this will be useless. Would look funny, right? When we use a wireless Headphone. But still use power supply with cable.

Remember that the audio is transmitted must have line of sight between the transmitter and receiver.

You can extend the range of the transmitter by placing more transistors BD140 with more IR LEDs.

Each time you press the doorbell generator creates a Ding-Dong weak audio signal with the sound of bells. The signal is high in volume by the amplifier and is reproduced by the speaker. The power supply circuit provides the voltage necessary to operate. The interface circuit to connect the rings fed centrally as buildings or intercom.

The circuit is powered through the point marked V + and ground. The heart of it is the integrated HT2811, developed by the firm koreana Holtek. For the pin 1 enters the trigger pulse, telling the chip to produce the sound “Ding-Dong”. Pins 2 and 3 are connected to sets RC establishing each of the sounds (2 = “Ding” / 3 = “Dong”). Altering these components is achieved by varying the sound of bells. Pin 4 is the mass. By the pin 5 leaves the audio signal which is amplified by a pair of transistors used in darlington configuration. The terminals 6 and 7 are connected to a 680K resistor which adjusts the gain of the internal preamplifier chip. Finally the terminal 8 enters the feed to the chip which is current limited by the resistance of 100 ohms and 3.3v stabilized by means of zener diode. The 100μF capacitor filters the possible ripple left in the power line.

In case of using this bell at departments or locations where you can not modify the wiring in the bell push is necessary to use this interface. It receives at its input an AC or DC voltage and rectifies through PR the bridge rectifier whose output is filtered by continuous capacitor 470μF and subsequently attacks the small coil of a reed relay. The key to this relay trips the main circuit as would a conventional switch. The rectifier bridge (PR) can be either formed by diodes 1A 250V or more. While the voltage of the relay coil must be the same as the voltage of the previous original buzzer ring (usually 12V). While the relay can be operated without rectifying the line or filter is not suitable because the alternating current would act to relay as a buzzer, opening and closing your key 50 times per second and this can cause some damage in the mechanism after a time.

This section of the circuit adapts the voltage from the power supply required by the household the equipment. It also enables battery power for all occasions when the power fails. The transformer reduces the voltage AC 4.5v. The bridge rectifier (PR) converts AC power continuously, which is filtered by the capacitor of 2200μF. The 1N4007 diodes act as source selector system by operating the mains or batteries as needed. The fuse protects the transformer section 220v. The bridge rectifier (PR) can be any voltage which is greater than 250V and whose current is not lower than 1A. Point + V represents the output of the source, while the batteries (4 in series) input by the points + Bat and-Bat.

This metal detector electronics circuit also detects metal objects and magnets. When the magnet is near the 10 mH coil, a metal detector project can be supported by a power supply that can provide a DC output voltage of 6 volts to 12 V. If the metal is closer to the coil L1, it will produce a change in the oscillation frequency of the output, which will produce sound at 8 ohm speaker.

Parts list :
R : 47K
C : 2.2uF (2) 10uF
L : 10uH
IC : 555
Speaker 8 ohm
Supply voltage 6-12V

By adjusting the potentiometer P2 to a high pitch, can enter the circuit into oscillation by emitting a continuous whistle.In this case, we must reduce degradation of sound with the potentiometer P1. For installation components, follow closely the diagram layout.

Bell Electronic Parts list :

All resistors are 1/4 watt unless otherwise stated.
R = 68 ohms
R2 = 1 kohm
R3 = 10 Kohm
R4 = 470 ohms
R5 = 82 Kohm
R6 = 22 Kohm
R7 = 270 ohms
R8 = 10 Kohm
R9 = 47 ohms
Pl = 4.7 MohmsA.
P2 = 220 Kohm A.
Cl = 22uF16V elec.
C2 = 1uF16V elec.
C3 = 0.1 uF 100 Vpol.
C4 = 0.047 uF 100 Vpol.
C5 = 0.047 uF 100 Vpol.
C6 = .47 uF 100 Vpol.
IC1,IC2,IC3 = 741
P = Push.
3 IC Supports 8-pin

These integrated circuits operating at 5 V and 9 V battery 6F22 certainly convenient, voltage is reduced and stabilized by a 78L05 regulator. By rotating the trimmer R2 from one end to another, will change the flashing between 0.5to 3 flashes per second.

This electronic flasher circuit can be placed in bags or placed in a belt to put on waist (when cycling,walking, etc..). You will see this safety circuit is highly efficient flashing in the darkness. Moreover, nothing prevents to build a (relatively inexpensive) and set them on someplaces (legs, back, bike, scooter …) to improve visibility.

List of electronic components Led electronic flasher:
R1 …………… 2.2 kOhms
R2 …………… 10 k trimmer
R3 …………… 220 Ω
R4 …………… 220 Ω
C1 …………… 47 uF electrolytic
C2 …………… 47 uF electrolytic
C3 …………… 47 uF electrolytic
DL1 …………. LED
DL2 …………. LED
IC1 ………….. integrated SN74HC132
IC2 ………….. integrated MC78L05
S1 …………… switch
(Unless otherwise noted, all resistors are 1/4 W 5%

The pin 3 (non-inverting) of the operational amplifier IC1 is connected to the junction of the LDR and R1 trimmer. The LDR being connected to + 12 volts and the trimmer to ground, together form a bridge with a variable value. The opposite pin (inverting) of the operational amplifier is connected to the junction of two resistors R2 and R3, R2 being connected to + 12 volts and R3 to ground, together form the fixed bridge. Voltage at the output of operational amplifier is 6 volts. When the LDR is illuminated by light, at pin 3 of IC1, we have a positive voltage is higher than that present at pin 2and therefore the output pin 6 of IC1 is at logic 1 (at + 12 volts).

The resistor R4 therefore can not biasing the transistor which isa PNP, relay remains inactive. When the LDR is placed in the dark, the pin 3 of IC1 has a lesspositive voltage on pin 2. Therefore, the output pin 6 of IC1 is at logic level 0 (ground). The resistor R4 is grounded and the base of transistor TR1 is biased (PNP).  The latter then becomes conductive and the relay placed in the collector is activated. which used to control any load. The trimmer R1 connected in series with the photoresistor used for test the detection sensitivity.

Parts list :
R1 ………. 10 k trimmer
R2 ………. 10 k
R3 ………. 10 k
R4 ………. 1.2 kOhms
R5 ………. 1.2 kOhms
FR1 ……… photoresistor
C1 ………. 100 uF electr olytique
DS1 …….. 1N4007 diode
TR1 ……… 2N3702 PNP
IC1 ……… Integrated uA741
RL1 ……… Relay 12 V 1 R

In addition, drift rates are far superior to vacuum tube circuits allowing a 0.5 volt full scale range which is impractical with most vacuum tubes. The low-leakage, low-noise 2N4340 is an ideal device for this application.

Current meter ranges from 100 pA to 3 mA full scale. Voltage across input is 100 µV at lower ranges rising to 3 mV at 3 mA. The buffers on the op amp are to remove ambiguity with high-current overload. The output can also drive a DVM or a-DPM.

Parts list :

Parts list :
R1 : 20K
R2 : 60K
R3 : 30K
R4 : 1M
R5 : 1G
R6 : 10K
R7 : 1K Variable
R8, R9 : 2K
R10 : 6.65K
R11 : 2K8
R12 3.32K
R13 : 1K
R12 0.8 ohm
C1 : 30pF
D1 : LM385 1,2V
D2,D3 : 1N457
Q1 : 2N2484
Q2 : 2N2219
Q3 : 2N2905
A1 : LM11
M1 : 100uF

This zener tester based on famous 741 operational amplifier. RV1 can be calibrated in volts, so that when LED 1 just lights, the voltage on pins 2 and 3 are nearly equal. Hence, the zener voltage can be read directly from the setting of RV1. The supply need only be as high a value as the zener itself For a more accurate measurement, a precision pot could be added and calibrated.

Zener tester parts  list :
R1 : 4K7
RV1 : 10 K linier variable resistor
Led
IC1 :  LS741