RS-232 POWER TEMPERATURE SENSOR CIRCUIT DIAGRAM

RS-232 POWER TEMPERATURE SENSOR CIRCUIT DIAGRAM
The temperature sensor converts this temperature into a square wave with a frequency proportional to the absolute temperature of its package, while drawing little supply current from the power source. The amplitude of the output signal is equal to the power supply of the chip, and must be sent over a cable to the host system. The use of a RS-232 interface, low-power dedicated chip enables the communication, while providing power to the sensor.

ROOM TEMPERATURE CONTROLLER USING LM35 SCHEMATIC DIAGRAM

ROOM TEMPERATURE CONTROLLER USING LM35 SCHEMATIC DIAGRAM
When the temperature on IC LM35 is low, the output voltage also low. If the electric voltage of the transistor is below the transistor active area, the voltage will be blocked, LED will off, relay for the fan circuit in open condition, thus the fan is off.

When the temperature of LM35 is high, the output voltage is also high. If the transistor electric voltage in the transistor’s active area, the LED will on, relay on the fan in close condition, thus the fan will be turn on.

Components :
Resistor R1 : 10k ohm
Resistor R2 : 4.7M ohm
Resistor R3 : 1.2k ohm
Resistor R4-R5 : 1k ohm
Resistor R6 : 330 ohm
Capacitor C1 : 0.1 uF
Polar capacitor C2 : 470 uF/25V
IC1 : LM35
IC2 : TL431
IC3 : LM358
Q1 Transistor PNP : BC557
Zener diode D6 : 13V/400mW
Diode D1-D2 : 1N4148
Diode D3-D4 : 1N4007
Relay K1 : 12V SPDT
LED
12V power supply

PHONE CONVERSATION RECORDER SCHEMATIC DIAGRAM

PHONE CONVERSATION RECORDER SCHEMATIC DIAGRAM
D1-D4 diodes serves as a device to convert the alternating current from the telephone line to become direct current in order to be used as a voltage activator. 12V zener diode lowers the voltage to 12V. When the phone receiver has not been appointed, the T1 voltage value will be low. This causes the transistor T2 on its cut off state and deactivate the relay. If the phone receiver is picked up, the voltage flows from T1 to T2. This activates the relay and turn the tape recorder on.

Components list :

Resistor R1 : 8k ohm
Resistor R2 : 2k2 ohm
Resistor R3 : 1M ohm
Resistor R4 : 100k ohm
Resistor R5 : 4k7 ohm
Diode D1-D4, D6 : 1N4001
Zener diode D5 : 12V
Transistor T1-T2 : BC548
Polar capacitor C1 : 0.001 uF/150 V
Polar capacitor C2 : 100 uF/25 V
Relay : 6V, 100 ohm

MAGNETIC SENSOR SCHEMATIC CIRCUIT DIAGRAM

MAGNETIC SENSOR SCHEMATIC CIRCUIT DIAGRAM
The principle of this circuit is, whenever a magnet comes close to the sensor, then the sensor will flow the output voltage to IC1. The output voltage will activate the timer which will then activate the relay controlled by IC2.

Component List :

Diode D1 : 1N4001
Resistor R1 : 10k ohm
Resistor R2 : 470k ohm
Resistor R3 : 1k ohm
Resistor R4 : 47k ohm
Polar capacitor C1 : 2.2 uF/16V
Polar capacitor C2 : 470 uF/16V
Transistor T1 : SL100
IC1 : NE555
IC2 : CD4013
Relay RL1 : 12 V, 200 ohm
Magnetic Sensor
5mm LED

LOCAL TELEPHONE LINE WITH DIVERTING SWITCH CIRCUIT SCHEMATIC DIAGRAM

LOCAL TELEPHONE LINE WITH DIVERTING SWITCH CIRCUIT SCHEMATIC DIAGRAM
In normal state, telephone no.1 and telephone no.2 can be used as an intercom when telephone no.3 is connected with the phone cable. To be used as an intercom, pick up telephone no.1 and push switch S1, then piezo buzzer 2 will sound, and so on.

Components :
Resistor R1 : 4.7k ohm
Polar capacitor C1 : 2.2uF/100V
PZ1-PZ3 : Piezo buzzer
S1-S2 : Push button
S3 : ON/OFF stereo switch
12V DC/200 mA power supply

HEADPHONE CIRCUIT FOR FIXED TELEPHONE LINE SCHEMATIC DIAGRAM

HEADPHONE CIRCUIT FOR FIXED TELEPHONE LINE SCHEMATIC DIAGRAM
This circuit requires low power, therefore can be installed parallel with the telephone. Transistor T1, Resistor R2,R3, and Zener diode are used to lower the input voltage become 5V. Transistor T2, resistor R6,R7, and capacitor C5 are used as the sound amplifier. This circuit is equipped with condenser microphone to speak and earphone to hear.

DIGITAL VOLUME CONTROL SCHEMATIC DIAGRAM

DIGITAL VOLUME CONTROL SCHEMATIC DIAGRAM
It uses one IC DS1669 and some additional components. S1 works as an addition to audio volume, S2 works as audio volume subtractor.

Components list :

Capacitor C1 : 0.1 uF
Switch S1-S2 : Push button
IC : DS1669
5V DC power supply