Human

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'. ..

Touch Switch with MPF102 JFET

Touch Switch with MPF102 JFET

Q2 is held cut off since Q1 normally is conducting. When the touch plate is contacted by a large object (human body, etc.), stray 60-?? pickup is rectified by D1 and D2, and produces a negative voltage across R2-C2 and the gate of Q 1. Q1 cuts off, causes Q2 to conduct, and the output goes low. ..

Heartbeat monitor

Heartbeat monitor

? simple heart-beat transducer can be made from an infrared LED and an infrared phototransistor. ?t works because skin acts as a ref1ecti?e surface for infrared light. The lR ref1ecti?ity of one's skin depends ??? the density of blood in it. Blood density rises and falls with the pumping action of the heart. ..

Whistle on / off switch

Whistle on / off switch

This is an extension of the CMOS toggle flip flop circuit shown in the "Circuits controlling relays" section with the addition of two bandpass filters and condenser microphone so the relay can be toggled by whistling at it. The condender mic used is a PC board mount Radio Shack #270-090C. The filters are tuned to about 1700 Hz, or the third Ab above middle C on a piano keyboard which is a fairly easy note for me to whistle. Resistor values for the filter can be computed using the three formulas below but we need to assume a gain and Q factor for the filter and the Q of the circuit must be greater than the square root of (Gain/2). ..

Touch switching 12V Light

Touch switching 12V Light

The circuit on the right uses three bipolar transistors to accomplish the same result with the touch contact referenced to the negative or ground end of the supply. Since the base of a bipolar transistor draws current and the current gain is usually less than 200, three transistors are needed to raise the microamp current level through the touch contacts to a couple amps needed by the light. For additional current, the lamp could be replaced with a 12 volt relay and diode across the coil...

Touch Switch sensor circuit

Touch Switch sensor circuit

Similar to the CMOS based Touch Switch also on this site, this transistor based touch switch can activate a load simply by the user touching a metal plate. It is designed to directly switch a relay to allow it to be used with large loads. As it uses only a few commonly available transistors and a 12V supply, it is ideal for hostile environments where mechanical switches would be damaged. Using a latching relay and two of these circuits, a simple two pad "touch on/touch off" arrangement can be made...

Human detector circuit

Human detector circuit

This is a circuit thich I originally included in my book, 22 Tested Transistor Projects, published by Babani Press in 1976 (ISBN 0 900162 63 S). It is one I had great fun with. It uses the PUT Complimentary Feedback Pair as a sensitive detector of changing electric fields to switch on an oscillator and make a noise. It is so sensitive that it can be difficult to get it working on a test bench because of all the electric fields, but put it on a table and leave it. Then when you walk up to it, your movement is likely to cause enough field change to trigger it. Triggering not only depends on how fast you approach it but also on the clothes you are wearing, the relative humidity and your own body capacity and skin conductivity, so it reacts differently to different people. Some it reacts to not at all, others cannot even approach it...

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. ..

infrared beam proximity detector

infrared beam proximity detector

his circuit can be used as an Infrared beam barrier as well as a proximity detector. The circuit uses the very popular Sharp IR module (Vishay module can also be used). The pin nos. shown in the circuit are for the Sharp & VIshay modules. For other modules please refer to their respective datasheets. The receiver consists of a 555 timer IC working as an oscillator at about 38Khz (also works from 36kHz to 40kHz) which has to be adjusted using the 10K preset. The duty cycle of the IR beam is about 10%. This allows us to pass more current through the LEDS thus achieving a longer range. ..

Touch Switch illuminates LED

Touch Switch illuminates LED

Our circuit is amplifying the current flowing through your finger (when it touches the touch plate) 10,000 times and this is sufficient to illuminate the LED. The current flowing through your finger (when touching the touch plate) is only a few microamps and this is not enough to illuminated the Light Emitting Diode (LED). We need an amplifier with considerable gain to get the LED to light and this is what the circuit does. You can alter the brightness of the LED by pressing lightly on the plate and this will show that the resistance of the plate changes with the amount of pressure you exert. You can also moisten your finger to see how this changes the resistance of the plate and observe the brightness of the LED. ..

Touch detecting Switches

Touch detecting Switches

One of the unusual features of the out-of-production Programmable Drum Set was its use of touch switches for control. Like most touch switches, these detect the difference in the capacitance of a plate when it is being touched by a finger versus the parasitic capacitance of the plate alone. The capacitance added by touching the plate is detected using a square wave oscillator. In the diagram below IC1:A and IC1:B, two gates from a 4001 CMOS Quad NOR IC, form an astable multivibrator with a 50kHz frequency as determined by the time constant of R2 and C2. The square wave output is buffered by IC1:C and used to drive a group of touch switches. Only two switch plates - TS1 and TS2 - are shown in the illustration, but in the PDS, 16 touch switches were excited by this one clock...

Infrared motion detector

Infrared motion detector

The GLMDA is designed to detect the motion of a human or animal both in daylight and at night and to provide a normally open relay output that can be used to activate many types of loads. The GLMDA also has terminals for connecting an optional photocell to prevent activation of the load during daylight. ..

Touch Light Dimmer circuit

Touch Light Dimmer circuit

With this circuit we can change the brightness of lamb, with a only key of touch. The key of touch is connected in the circuit, center of which is a special completed IC1, which is the S566B of SIEMENS. This IC, it processes the information of duration of touch and then it checks the brilliance of lamb, according to this information. If we touch upon the key for a small period of time (60 until 400 ms), the lamb simply only changes situation, that is to say from OFF in ON or on the contrary, depended from the situation is found itself before the unit. In one of bigger duration of touch (more from 400ms), is altered the brilliance of lamb, late from dark in luminous or on the contrary. Are required roughly seven seconds, in order to we have complete brilliance. ..

Touch Switch with relay

Touch Switch with relay

A simple circuit with which we have the possibility opening and closing the RL1 contacts. He becomes touching a small metal surface. Clue of situation that is found RL1, is become by the Led D3. The supply of circuit is +12V, the IC1 is supplied with 3.9V fall of voltage that is ensured by combination R5 and zener D2. For more good restoration perhaps it should adaptation of R1 value. ..

Touch Switch with 555

Touch Switch with 555

The modern mechanic switches are improved concerning of old technology. We need however many times to replacement some old switch or to check currents bigger than the durability of certain switches or simple we need something with modern appearance. For he and different reasons is essential the up circuit. He is simple in the manufacture and the materials that use they exist everywhere. This based in the known 555, which drives a relay of which the contacts play the role of switch. The metal surfaces can have what form we want, but it should they are clean and near in the circuit. ..

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