Various Circuits

Infrared approach detector / sensor

Infrared approach detector / sensor

Basic operation of the monitor attached to the circuit is to detect objects (obstacles), at distances ranging from a few millimeters to and a few centimeters. Depending circuits used in industry and hospitals. The position sensor IC2 optoapomonotis used a type of Siemens SFH900 someone similar. The sign shows, led to a phase locked circuit (contained in IC1), which compares with signal frequency an oscillator which is also located within the same chip. For as long as the frequencies of two signals coincide, the pin output of IC1 (pin 8) is still reasonable 'O'. ..

Detection for trains on model railway

Detection for trains on model railway

This light valve can be used for example to detect trains on model railway or a lap counter at the close racing. D3 receives a constant stream of power built around T1. When the light beam from D3 to T3 is not interrupted, led T3 and T2 is the basis of practically grounded. T2 not conduct and the LED is not lit. When the beam is interrupted, spert T3 and T2 conducts and the LED will light. Of course listen to other things like LED control between plus and the collector of T2. Please note the maximum load of 100 mA. The supply voltage may be between 4.5 and 12 volts...

Toy Train rail detector circuit II

Toy Train rail detector circuit II

This circuit can detect whether a train in a particular drive. The output is TTL and CMOS compatible and can be processed by such a computer. The simple circuit works. The driving voltage is connected to the two terminals left. When the locomotive of the interrupted line is, the flow leading to the locomotive goes through the triac T1. This is then a voltage of about 1 V, which is conducting T3 or T4. Therefore, the LED D1 on and the output is logical zero. ..

Toy Train rail detector circuit

Toy Train rail detector circuit

This circuit must be used between the drive voltage of such a transformer and track. On JP1, the transformer is connected to JP2, the rails are connected to JP3, is a TTL "High" position when there is a tax on the trail is more of 2mA, but given the average LED more consumption, this should not be a problem. Works through a circuit voltage of 1.4 volts over the diodes, which are anti-parallel so that the circuit in both directions to use. ..

Fan Failure Detector circuit

Fan Failure Detector circuit

The cooling is not only a PC using a small fan with an electronic commutator [1]. A special feature of these fans is that their removal is less dependent on the load. Indicators monitoring the DC component of current may therefore be very reliable. Interesting connection indicator I found in Electronic Design magazine [2]. The indicator in Figure 1, the only change in passing current. Measured current waveform is the fan in Figure 2 The voltage at the base of the transistor is filtered by resistor R1 and capacitor C1. The immediate changes in the supply current (during the fall) opens the transistor and discharges the capacitor C2. ..

Tactile sensors Motor controller

Tactile sensors Motor controller

It's basically a photovore with a couple tactile sensors. It's rather complex but can give neat behaviors with modifications to the circuit. At this point I don't have any plans to give more information on this circuit so your on your own. C1 and C2 values C1 and C2 are the capacitors that control how long each motor will reverse after the tactile sensor is triggered. Increasing the value will cause your bot to turn more after bumping an object. Decrease and it will turn less. The layout All resistors are 1M unless labeled otherwise. All capacitors are .22uF unless labeled otherwise. This circuit is more for advanced BEAMers so if your a newbie to BEAM I would recommend the iVore circuit. I may get some more info on the circuit on the web but no plans yet...

Audio Detector switch

Audio Detector switch

The following circuit can be used to detect those annoying piezo whistles that one can get from Radio Shack. For the Trinity Home Fire Fighting Contest, additional points accrue when the robot is started by a sound similar to a fire alarm. The actual whistle is specified as a particular Radio Shack piezo element, but the following circuit should be tunable across a wide range of pitches...

Video Activated Relay

Video Activated Relay

This simple circuit from the May 1996 Think Tank column of Popular Electronics activates a relay when it senses a composite video signal. This allows you to use the tuner built into your VCR to turn on and off older TVs that are not equipped with a remote. It can also be used to activate surround sound equipment, turn off the room lights, turn on video game consoles, etc. For such a simple circuit, it is very versatile...

Battery Current Sensor

Battery Current Sensor

These controllers have an inhibit input and the effect of shorting this down to ground is to turn down the internal demand speed. So with the battery current limiter fitted, the internal demand speed can only ramp up to a value which engages the limit. Some enthusiasts of electrically assisted cycles believe constant power acceleration is the ideal response. Although personally I am not convinced that constant power acceleration is the ideal, limiting the battery current gives constant power acceleration whenever the limit is engaged...

Current Loop Sensor Interface

Current Loop Sensor Interface

This is a very simple circuit to interface a current loop sensor to an input which is designed for a voltage, such as that from a standard potentiometer. This page is technical so that interested persons can build the circuit themselves, but 4QD can also supply the interface on a 'postage stamp' sized (22mm x 27mm) board as shown in the first diagram. It is a relatively trivial circuit! This circuit was developed to interface one of the new type contactless (inductive) throttle sensors to 4QD's motor controllers for use in a conversion to an Eze-Go golf car. ..

Touch Switches Collection

Touch Switches Collection

Touch operated switches are an attractive project for DIY electronics but they are not so common in commercial products. The reason for this is that, although there are many different ways of implementing a touch switch (leakage, hum pickup, capacitance, albedo) all of them rely on body parameters which vary a lot with the person's body, age and environment so that a circuit which gives reliable operation with one development engineer may cause problems in use with, for instance, old folks living in arid areas. Nevertheless touch switches can give excellent results. ..

Infra-red detector circuit

Infra-red detector circuit

This circuit is a simple IR detector for testing IR remote controllers. The circuit is based on one phototransistor which receives the IR beam. The NPN transistor works as an amplifier which feeds current to the led. When this circuit detects IR or light, the LED is on. So you need to shield the phototransistor from ambient light if you don't want to do your tests in the dark. The best way is to fit the phototransistor in a small black tube. I used 2 cm long piece of insulating tube and fitted the phototransistor into the middle of the tube...

Acceleration sensing USB interface

Acceleration sensing USB interface

The TiltStick is a small acceleration sensing device in form of a USB stick. It's using a two axis acceleration sensor to measure acceleration (caused e.g. by motion and tilt). The device is emulating a USB joystick and can thus be used in conjunction with any USB equipped host (e.g. a standard PC or the Nokia N8XX family) without any special drivers. The TiltStick is the successor of the Tilt Dongle for Palm OS. Two versions of the TiltStick have been designed based on different 2D accelerometer chips. The slightly smaller one is based on the Analog Devices XL203 (the XL202 may also be used). ..

Color Sensor circuit

Color Sensor circuit

Colour sensor is an interesting project for hobbyists. The cir- cuit can sense eight colours, i.e. blue, green and red (primary colours); magenta, yellow and cyan (secondary colours); and black and white. The circuit is based on the fundamentals of optics and digital electronics. The object whose colour is required to be detected should be placed in front of the system. The light rays reflected from the object will fall on the three convex lenses which are fixed in front of the three LDRs. The convex lenses are used to converge light rays. This helps to increase the sensitivity of LDRs. Blue, green and red glass plates (filters) are fixed in front of LDR1, LDR2 and LDR3 respectively. When reflected light rays from the object fall on the gadget, the coloured filter glass plates determine which of the LDRs would get triggered...

Dew sensor circuit

Dew sensor circuit

Dew (condensed moisture) ad- versely affects the normal per- formance of sensitive electronic devices. A low-cost circuit described here can be used to switch off any gadget automatically in case of excessive humidity. At the heart of the circuit is an inexpensive (resistor type) dew sensor element. Although dew sensor elements are widely used in video cassette players and recorders, these may not be easily available in local market. However, the same can be procured from authorised service centres of reputed companies. The author used the dew sensor for FUNAI VCP model No. V.I.P. 3000A (Part No: 6808-08-04, reference no. 336) in his prototype. ..

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