Sunday, August 5, 2012
FM Telephone Transmitter
The FM telephone circuit is built on a PC board that is so small it can easily be fitted inside the housing of a telephone making it an instant pseudo-speak earphone.
Here's the FM telephone transmitter circuit :
This FM circuit connects in series with telephone line, steals power from it, and transmit at both sides of the conversation to an FM radio tuned between 90 and 95 MHz.
[read here...]
Here's the FM telephone transmitter circuit :
This FM circuit connects in series with telephone line, steals power from it, and transmit at both sides of the conversation to an FM radio tuned between 90 and 95 MHz.
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| FM Telephone Transmitter |
Friday, August 3, 2012
Light Alarm Circuit Using LDR
This light alarm circuit is very simple and very easy to assemble even for beginners though it is not difficult. The well-known UM66 is used as the sound generator and Will give a pleasent wake up alarm.
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| Light Alarm Circuit Using LDR |
UM66 Pinout
LDR is a light dependent resistor. Normally the resistance of an LDR is very high, Sometimes as high as 1MΩ, but Pls They are illuminated with light resistance drops dramatically. In the circuit adjust the presets to the Desired 220KΩ sensitivity, meaning adjusting the threshold point where the alarms start singing.
When there is light on the light dependent resistor the transistor T1 will from the start conducting and musical UM66 powers the integrated circuit.
for more details about LDR light alarm circuit please visit http://electroschematics.com/6353/light-alarm-circuit-with-ldr/
Wednesday, August 1, 2012
TDA0161 Metal Detector
This metal detector circuit diagram is based on the IC TDA0161, designed for metallic body detection by detecting the variations in high frequency Eddy current losses. For detecting metals , TDA0161 require an external LC tuned circuit .
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| TDA0161 Metal Detector Circuit |
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| TDA0161 Pin-Out |
Output signal is determined by supply current changes. Independent of supply voltage, this current is high or low according to the presence or the absence of a close metallic object. This medal detector circuit use two LEDs , which offer an visual indication of presence or absence at a metals ,around the coil . To adjust the circuit you need to make sure there is no metal near the coil and then set the fine adjustment to a "Mid position". After that you need to adjust the course adjustment to turn on the LED and , adjust the fine adjustment to turn off the LED.
This metal detector electronic circuit operates over a wide range input voltage of 4 -35 volts . If you want you can use other values for the Cx capacitor and for L1 inductor ( changing this value will affect the frequency oscillation and the detection range ).
Simple Touch Switch Circuit Using Transistor
A simple electronic touch switch can be constructed using this circuit diagram . This electronic touch switch is based on two transistors an can activate a relay , when the touch sensor is pressed .
[read here...]
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| Simple Touch Switch Circuit Using Transistor |
The touch sensor can be constructed using a small piece of a printed circuit board ( two small tracks with a 2 mm distance between each other ) . This circuit is powered using a 12 volts DC power supply , so the relay used for this project must be a 12 volts relay . This circuit is working very simple , when both plates of the sensor are touched the skin resistance will activate the circuit .
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