Showing posts with label detector. Show all posts
Showing posts with label detector. Show all posts
Wednesday, November 5, 2014
Simple Dag gerboard Position Detector
It is easy to build Dag-gerboard Position Detector Cirucit. In sailing regattas it’s handy to have a dag-gerboard that can be raised and lowered vertically. As the winding handle or positioning motor needs to rotate the spindle of the lifting device some 100 to 150 times throughout its full range it would be extremely handy to have a quick idea of its current position. An electronic count of the number of revolutions would be ideal. Thank goodness most sailors now have a 12-V supply available!
To get this to work you need to apply white and black markings to the spindle, each covering half of the circumference. Next, mask off two electric eye devices (reflected light sensors) next to one another (approximately 10 mm apart). For secure detection both sensors should be positioned not more than 5 mm from the paint markings.
Dag-gerboard Position Detector Circuit Diagram :
![Detector]()
The markings to be read by the sensor should be displaced laterally, so that the direction of rotation can be recognised in addition to the number of revolutions counted. At the heart of our circuit is a PIC16F628 from Microchip, which as usual can be bought ready programmed from Elektor or you can do this bit yourself by downloading free firmware (for details of both see [1]).
At pins 1 of the two reflected light sensors IC3 and IC4 we need to ‘see’ more than 2.0 V from the white segment and less than 0.8 V from the black mark (with an operating volt-age between 4.5 and 5.5 V). The two signals detected are taken to plug connector along with the operating voltage and ground. It’s convenient if you also provide a connector from the microcontroller as well, so that the sensor and the controller board can be linked by a test lead.
The multiplexing of the three seven-segment displays is programmed at a rate of 100 Hz.
Acceptable values for the revolution count are between 0 and 140. If the count exceeds or falls below these limits, then the counter is not incremented. The RESET key S2 sets the counter back to zero. Jumper K2 enables you to reverse the direction of counting. The count is retained if the operating voltage is removed and is loaded again when next pow-ered up.
The source code can also be downloaded from the website mentioned above, making it possible (for instance) to define alternative counter limit values (the maximum value is defined in the line #define max 140). For compiling the code you can use the CC5X compiler, of which there is a free version (www.bknd.com/cc5x).
To get this to work you need to apply white and black markings to the spindle, each covering half of the circumference. Next, mask off two electric eye devices (reflected light sensors) next to one another (approximately 10 mm apart). For secure detection both sensors should be positioned not more than 5 mm from the paint markings.
Dag-gerboard Position Detector Circuit Diagram :
The markings to be read by the sensor should be displaced laterally, so that the direction of rotation can be recognised in addition to the number of revolutions counted. At the heart of our circuit is a PIC16F628 from Microchip, which as usual can be bought ready programmed from Elektor or you can do this bit yourself by downloading free firmware (for details of both see [1]).
At pins 1 of the two reflected light sensors IC3 and IC4 we need to ‘see’ more than 2.0 V from the white segment and less than 0.8 V from the black mark (with an operating volt-age between 4.5 and 5.5 V). The two signals detected are taken to plug connector along with the operating voltage and ground. It’s convenient if you also provide a connector from the microcontroller as well, so that the sensor and the controller board can be linked by a test lead.
The multiplexing of the three seven-segment displays is programmed at a rate of 100 Hz.
Acceptable values for the revolution count are between 0 and 140. If the count exceeds or falls below these limits, then the counter is not incremented. The RESET key S2 sets the counter back to zero. Jumper K2 enables you to reverse the direction of counting. The count is retained if the operating voltage is removed and is loaded again when next pow-ered up.
The source code can also be downloaded from the website mentioned above, making it possible (for instance) to define alternative counter limit values (the maximum value is defined in the line #define max 140). For compiling the code you can use the CC5X compiler, of which there is a free version (www.bknd.com/cc5x).
Author : Hermann Sprenger - Copyright : Elektor
Tuesday, November 4, 2014
Metal Detector Circuit Schematic using Beat Frequency Oscillator BFO
The simplest method of detecting metal is by beat frequency oscillator. The circuit basically consists of two balanced oscillator. One acts as the detector element, the other provides the reference signal. This oscillator frequency reference is set to fix value, whilst the detector oscillator varies depending on the metal presence. The reference oscillator can be constructed using various circuit topology: inductor-capacitor (LC), resistor-capacitor (RC), or even a crystal (quartz) oscillator. While the reference oscillator can be implemented using various circuit topology, the detector oscillator always use inductor-capacitor topology, because the mechanism will be using the magnetic induction property of the detected object, and the inductor component of the detector oscillator will be the detecting probe.
With the absence of a metal near the detector probe (the inductor component of the detector oscillator), the detector oscillator is tuned to have same frequency as the reference oscillator. The output of the detector oscillator and the reference oscillator output is mixed using hetero-dyne mixer circuit, producing a beat frequency output of zero Hz, or a very low frequency if both oscillator is slightly unbalanced. In the presence of a metal near the detector probe, the detector oscillator will shift it’s frequency, and the mixer output will produce a tone with frequency equal to the difference of the reference and the detector frequency.
The figure below shows one of the simple metal detector circuit.You can see the reference circuit is a simple RC circuit, and its frequency is determined by R1-P2-C1. The detector oscillator is an LC oscillator with the frequency is determined by the L1-C2-C3 values.
The NAND gates use CMOS 4011 chip, a low power component that is suitable for this battery-operated circuit. You can see that this chip is supplied by a 5V voltage coming from an LM7805L regulator. You might wonder what the purpose of this regulation is, since the power supply come from a 9V battery and the CMOS gates can handle the voltage of 3-15 Volt. The main purpose of the regulator is to keep a constant voltage source for the reference oscillator frequency stability, since the frequency is affected by the power supply voltage variation as the battery voltage drops in the long time of usage.
Here the complete parts list:
Parts list:
U1: CD4011
U2: LM389
U3: 78L05
R1: 2.2k 5%
P2: 4.7k lin.
R3: 330k 5%
R4: 270k 5%
R5: 1k 5%
C1: 390pF (NPO)
C2,C3,C4: 10nF
C5: 10uF 16v electrolytic
C6,C8: 220 uF 16v electrolytic
C7: 100uf 16v electrolytic
C9: 100nF ceramic
P1: 4.7k log
L1: 22cm in diameter with 14 turns AWG 26
K1: SPDT toggle switch
J1= Headphone jack 1/4 or 1/8 inch
Other parts: 9v battery connector, speaker or headphones
To tune the circuit, plug a headphone at the output, and remove any metal around the inductor L1. Set the volume control P1 around at center. Set the reference oscillator tuner P2 at the maximum or minimum position, you should hear no sound since the frequency should be in ultrasonic range. Turn slowly P2 until you hear a very high audio frequency, continue turning the pot until the frequency is decreasing and stop turning when the note is just disappeared (the frequency is decreased down below 20 Hz). After this, you can test the circuit by placing a metal near the inductor L1 and now the output will give an audible frequency as the detection alert.
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With the absence of a metal near the detector probe (the inductor component of the detector oscillator), the detector oscillator is tuned to have same frequency as the reference oscillator. The output of the detector oscillator and the reference oscillator output is mixed using hetero-dyne mixer circuit, producing a beat frequency output of zero Hz, or a very low frequency if both oscillator is slightly unbalanced. In the presence of a metal near the detector probe, the detector oscillator will shift it’s frequency, and the mixer output will produce a tone with frequency equal to the difference of the reference and the detector frequency.
The figure below shows one of the simple metal detector circuit.You can see the reference circuit is a simple RC circuit, and its frequency is determined by R1-P2-C1. The detector oscillator is an LC oscillator with the frequency is determined by the L1-C2-C3 values.
The NAND gates use CMOS 4011 chip, a low power component that is suitable for this battery-operated circuit. You can see that this chip is supplied by a 5V voltage coming from an LM7805L regulator. You might wonder what the purpose of this regulation is, since the power supply come from a 9V battery and the CMOS gates can handle the voltage of 3-15 Volt. The main purpose of the regulator is to keep a constant voltage source for the reference oscillator frequency stability, since the frequency is affected by the power supply voltage variation as the battery voltage drops in the long time of usage.
Here the complete parts list:
Parts list:
U1: CD4011
U2: LM389
U3: 78L05
R1: 2.2k 5%
P2: 4.7k lin.
R3: 330k 5%
R4: 270k 5%
R5: 1k 5%
C1: 390pF (NPO)
C2,C3,C4: 10nF
C5: 10uF 16v electrolytic
C6,C8: 220 uF 16v electrolytic
C7: 100uf 16v electrolytic
C9: 100nF ceramic
P1: 4.7k log
L1: 22cm in diameter with 14 turns AWG 26
K1: SPDT toggle switch
J1= Headphone jack 1/4 or 1/8 inch
Other parts: 9v battery connector, speaker or headphones
To tune the circuit, plug a headphone at the output, and remove any metal around the inductor L1. Set the volume control P1 around at center. Set the reference oscillator tuner P2 at the maximum or minimum position, you should hear no sound since the frequency should be in ultrasonic range. Turn slowly P2 until you hear a very high audio frequency, continue turning the pot until the frequency is decreasing and stop turning when the note is just disappeared (the frequency is decreased down below 20 Hz). After this, you can test the circuit by placing a metal near the inductor L1 and now the output will give an audible frequency as the detection alert.
Wednesday, September 3, 2014
RF AF signal detector
The series that we will make this is a special electronic circuit can be used to detect the presence or absence of signal AF / RF. The circuit is very neat and simple to make. Costs it takes quite cheap. If you are already assembling this circuit, then with easy reader determine whether there is AF or RF signal at a particular section of a circuit.
Basic circuit uses an audio amplifier and a loudspeaker with switch input for AF and RF signals. The whole device can be made small as possible so it can be included in a container to maintain security. Audio amplifier section in this series created by IC TDA 2822M, with low stereo power amplifier in 8-pin mini-DIP. IC is used as a bridge cofiguration to shrink to 250 mW output power, loudspeaker handle 4 ohm, 500mW. The current required is less than 10mA with voltage of 3V battery.
| RF-AF signal detector schematics |
How it Works circuit
When the selector switch in the AF position, working on the input audio signal AF amplifier input (pin 7 of IC 1) through a capacitor C2 and potentiometer VR1. Capacitors C2 always hold input amplifier of the DC voltage and make it happen in the audio signal frequency. Input Signal IC 1 can be arranged with the help of potentiometers VR1.
When the selector switch in position RF and demodulator detector circuit formed by capacitor C1, diode D1, and resistors R1 and R2 are connected to the input The set. When the audio signal is detected then it will actually go kerangkaian to be strengthened. Signal detection is done by plugging probe (probe) on the legs of the existing components.
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