Tuesday, November 19, 2013
Home Security System
This alarm circuit activates when S1 through S5 are activated. This lights LED1 and activates Q1 via IC1C and IC1D. RY1 is wired to self latch. S10 is used to reset. When key switch S1 is activated or when re-entry buttons at S6 are depressed, IC1C is deactivated until RC network R7/C3 charges.
Home Security System Circuit Diagram

Home Security System Circuit Diagram

Monday, November 18, 2013
Solid State Relay Required Only 50uA Drive Current
This circuit demands a control current that is 100 times smaller than that needed by a typical optically isolated solid state relays. It is ideal for battery-powered systems. Using a combination of a high current TRIAC and a very sensitive low current SCR, the circuit can control about 600 watts of power to load while providing full isolation and transient protection.
Solid State Relay Circuit diagram:

Solid State Relay Circuit diagram:

Source: Discover Circuits
Audio peak indicator circuit

The existence of the peak indicator (Audio Peak Indicator) in an audio device is needed. Audio Peak indicator is a simple circuit to detect the peak level of audio signal. Audio Peak indicator circuit is built with duabuah transistor and LED indicator as peak level detection of audio signals.
The main function of a series of Audio Peak indicator is to determine the occurrence of the peak level of audio signal which is more than +4 dB, equivalent to 1.25 V rms. If the received audio signal Audio Peak Indicator more than +4 dB was the LEDs in series Peak Audio This indicator will light. Audio Peak indicator circuit is mounted on the output audio system.
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| Audio peak indicator |
R1 = 10Kohm
R2 = 1.2Kohm
R3 = 220Kohm
R4 = 4.7Kohm
R5 = 4.7Kohm
C1 = 47uF 25V
C2 = 2.2uF 25V
Q1 = BC550C
Q2 = BC550C
D1 = Red Led
TV Remote Tester Circuit
The circuit is very effective to test the remote controls what still works or not, the remote record will be tested using infra red. Examples of the TV remote, AC and others. Please try I am sure 100% will be successful.
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| TV Remote Tester Circuit |
The workings of the circuit is very simple, when the infra red sensor receive infrared signals pin 2 sensor will produce a voltage, this voltage will drives the PNP transistor so that the LED lamp and piezo disc (BZ) is active. for the power supply you can use a 9 volt battery and then use IC 7805 or use 1.5 volt batteries x 3
Following the specification of components installed
Transistor BC557
TSOP 1738 Sensor Infra Red
R1 = 10k ohm ¼ watt Resistor
R2 = 1k ohm ¼ watt Resistor
R3 = 1k ohm ¼ watt Resistor
BZ = piezo disc
led
Sunday, November 17, 2013
LED Audio Level Meter Circuit
This circuit uses two quad op-amps to form an eight LED audio level meter. The op-amp used in this particular circuit is the LM324. It is a popular IC and should be available from many parts stores.
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| LED audio level meter schematic |
The 1K resistors in the circuit are essential so that the LEDs turn on at different audio levels. There is no reason why you cant change these resistors, although anything above 5K may cause some of the LEDs to never switch on. This circuit is easily expandable with more op-amps, and is not limited to use with the LM324. Pretty much any op-amp will work as long as you look up the pinouts and make sure everything is properly connected.
The 33K resistor on the schematic is to keep the signal input to the circuit at a low level. It is unlikely you will find a 33K resistor, so the closest you can get should do. The value of this resistor may need to be changed, so it is best you breadboard this circuit before actually constructing it on PCB. The circuit in its current form will accept line level inputs from sources such as the aux out on a Hi-Fi, all though could be easily modified to accept speaker inputs.
The audio + is connected to the main positive rail, while the audio - is used for signal input. The 50k pot can be used to vary the sensitivity of the circuit.
Fire Alarm using NE555 and temperature sensor

This is a simple series of fire alarms. In this series used NE555 timer and temperature sensor to detect high temperatures. The working principle of this temperature sensor that is when the temperature is high around the sensor then there is resistance on the sensor to be small.
However if the low temperature then the resistance will be high. If the resistance of small sensors, the voltage supply will be able to flow past the sensor and activate the transistor.

IC1 NE555 as a regulator of the audio frequency. Transistors 1 and 2 are used as a driver IC1. Output (pin 3) of IC1 would trigger a transistor base T3 (SL100), which drives the speaker to produce sound the alarm. Frequency NE555 depending on resistance values of R5 and R6 and the capacitance sensor C2 temperature. When the temperature gets hot, would provide a low resistance so that supply voltage can flow into the base of transistor T1 through a diode D1 and R2.
Capacitor C1 will charge a positive voltage so that it will increase the time when the fire alarm. The greater the value of C1, the greater the positive bias applied to the base of transistor T1 (BC548). T1 collector coupled to the base transistor T2, transistor T2 provides a positive voltage to pin 4 (reset) from IC1 (NE555). Resistors R4 will make IC1 NE555 continued to be active despite no positive voltage flowing.
Hi Fi Audio Amplifier using TDA1514
The TDA1514 Hi-Fi Audio Amplifier was available on voguish grouping Amplifier. Please read carefully and observe on circuit design images of TDA1514 Hi-Fi Audio Amplifier to know itemize in a row.
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| Hi-Fi Audio Amplifier using TDA1514 |
The TDA1514 integrated circuit is a ciao-fi power amplifier in lieu of treatment for instance a corporation obturate in broadcasting, box and added audio applications. The TDA 1514 racetrack is completely battlemented, moreover has a nonspeaking organize to can be real illusory for a episode afterward power-on with a delay dimension unchangeable by outside components. The device is wilful in favor of centrosymmetric power stores but an unsymmetric allot may well in addition be utilized. For photo amplifier assemblage use two go well together circuits.
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