Sunday, December 22, 2013
Photodiode Alarm
This Photodiode based Alarm can be used to give a warning alarm when someone passes through a protected area. The circuit is kept standby through a laser beam or IR beam focused on to the Photodiode. When the beam path breaks, alarm will be triggered. The circuit uses a PN Photodiode in the reverse bias mode to detect light intensity. In the presence of Laser / IR rays, the Photodiode conducts and provides base bias to T1. The NPN transistor T1 conducts and takes the reset pin 4 of IC1 to ground potential. IC1 is wired as an Astable oscillator using the components R3, VR1 and C3. The Astable operates only when its resent pin becomes high. When the Laser / IR beam breaks, current thorough the Photodiode ceases and T1 turns off. The collector voltage of T1 then goes high and enables IC1. The output pulses from IC1 drives the speaker and alarm tone will be generated.
Photo-Diode Alarm Circuit diagram
IR Transmitter Circuit diagram
A simple IR transmitter circuit is given which uses Continuous IR rays. The transmitter can emit IR rays up to 5 meters if the IR LEDs are enclosed in black tubes.
Photo-Diode Alarm Circuit diagram
Thursday, December 19, 2013
Luggage Security System
While traveling by a train or bus, we generally lock our luggage using a chain-and-lock arrangement. But, still we are under tension, apprehending that somebody may cut the chain and steal our luggage. Here is a simple circuit to alarm you when somebody tries to cut the chain. Transistor T1 enables supply to the sound generator chip when the base current starts flowing through t. When the wire (thin enameled copper wire of 30 to 40 SWG, used or winding transformers) loop around the chain is broken by somebody, the base of transistor T1, which was earlier tied to positive rail, gets opened. As a result, transistor T1 gets forward biased to extend the positive supply to the alarm circuit. In idle mode, the power consumption of the circuit is minimum and thus it can be used for hundreds of travel hours.
To enable generation of different alarm sounds, connections to pin 1 and 6 may be made as per the table.
| Select 1 (Pin6) | Select 2 (Pin1) | Sound effect |
| X | X | Police siren |
| VDD | X | Fire-engine siren |
| VSS | X | Ambulance siren |
| “-” | VDD | Machine-gun sound |
Note: X = no connection; “-” = do not care
Source: http://www.ecircuitslab.com/2011/05/luggage-security-system.html
Tuesday, October 8, 2013
Lie Catcher
Here is a circuit that you can have fun with your friends. Especially you can catch your girl friend or your boy friend when ever they say lies. Circuit is very simple and you can build it with in few hours. But you will surprise with the results.
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For two electrodes you can use wires but to get best results use electrode pads which use in the hospitals. Attach the electrode pads to the back of the hand from one inch apart. Make sure meter should be zero before you start. If the person is lying the meter point will get move.
To operate the circuit it needs two voltages separately as shown in the diagram. You can use alkaline batteries for long use or two 4.5 V two power packs if you want.
Saturday, October 5, 2013
2010 Ford Ranger XL Wiring Diagram
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| 2010 Ford Ranger XL Wiring Diagram |
The Part 2010 Ford Ranger XL Wiring Diagram: antena, cluster, panel illumination, sense, low current board, junction box, audio untit, power distribution, four door, speaker.
Wednesday, October 2, 2013
Electronic Ear for Lego RCX Module
One interface that is missing in the Lego MindStorms system is an electronic ear. We don’t mean that the RCX should respond to spoken commands (which requires a large amount of electronics and software), but it would be handy if it could respond to basic sounds (or sound levels). The circuit presented here allows the RCX to sense different sound levels. The sound is picked up by a crystal microphone, which is an inexpensive component that is available in every electronics shop. The signal from the microphone is converted into a variable quasi-resistance value. The RCX, in turn, can use this value to determine if a particular sound level has been exceeded. If the trigger threshold is set to the right level, the RCX will then react to a previously set sound level. The RCX input must be configured as a light sensor input for this function.
The operation of the circuit is simple. IC1, which is wired as a non-inverting amplifier, amplifies the microphone signal by a factor of 100. The output signal from the opamp is rectified by D1 and smoothed by C1. Resistor R2 allows the capacitor to discharge. The resulting DC voltage drives IC2, which acts as a buffer. The output of this opamp is connected to the sensor input of the RCX via a 1-kΩ resistor (R1). Just as with the analogue input adapter described elsewhere in this website, the RCX sees a variable resistance value at the sensor input, and it converts this into a measurement value between 0 and 100.
In the idle state, when no sound is sensed, the measurement value lies between 90 and 100. The louder the sensed sound, the lower the measurement value. You can use the light-sensor routine of the Lego software to set the responses to various sound levels. If you use a threshold value of around 85, then a level under 85 will be sensed as a sound signal, while a level above 85 will be sensed as silence. If you clap your hands near the sensor, the circuit will detect this. If you use these ‘observations’ to increment a counter, it is even possible to measure the number of sound pulses within a defined interval, and then to carry out some action based on the result.
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The operation of the circuit is simple. IC1, which is wired as a non-inverting amplifier, amplifies the microphone signal by a factor of 100. The output signal from the opamp is rectified by D1 and smoothed by C1. Resistor R2 allows the capacitor to discharge. The resulting DC voltage drives IC2, which acts as a buffer. The output of this opamp is connected to the sensor input of the RCX via a 1-kΩ resistor (R1). Just as with the analogue input adapter described elsewhere in this website, the RCX sees a variable resistance value at the sensor input, and it converts this into a measurement value between 0 and 100.In the idle state, when no sound is sensed, the measurement value lies between 90 and 100. The louder the sensed sound, the lower the measurement value. You can use the light-sensor routine of the Lego software to set the responses to various sound levels. If you use a threshold value of around 85, then a level under 85 will be sensed as a sound signal, while a level above 85 will be sensed as silence. If you clap your hands near the sensor, the circuit will detect this. If you use these ‘observations’ to increment a counter, it is even possible to measure the number of sound pulses within a defined interval, and then to carry out some action based on the result.
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