What makes this control unique is its momentum feature, which adds a degree of realism. The circuit will opera..
Ql is used as an oscillator around 300 kHz. R9 is set so that the oscillator just begins to run. An object ne..
When the plate is touched, the gate input becomes low, changing the state of the latch. ..
A high-frequency audio signal (15 to 25 kHz) generated by Ul is fed to buffer Ql and SPKR1. A portion is f..
The circuit is basically a NE555 monostable, the only major difference being its method of triggering. The trigger input is biased to a high value by the 22 ohm resistor. When the contact plates are touched, the skin resistance of the operator will lower the overall impedance from pin 2 to ground. This action will reduce the voltage at the trigger input to below the 16 Vcc trigger threshold and the timer will start. ..
Using an ISD1016 audio record/playback chip (Information Storage Devices, Inc.), this circuit records and plays back messages on command. Although intended for use with transmitters, it can be used as an electronic notepad, etc. ..
When the touch-on contacts are bridged, pin 6 of Ul-b goes low, which forces its output (the set output) at pin 4 to go high. That high divides along two paths; in one path, the output is applied to pin 2 of Ul-a, which causes its output at pin 3 to go low. That low is, in turn, applied to pin 5 of Ul-b, which latches the gate in a high output state. In the other path, the output of Ul-b is used to drive Ql. When Ql turns on, U2`s internal LED lights, which turns on its.....
LED1 and LED2 indicators turn on and remain on, each time the circuit is triggered. During the timing cycle, U1 "s Q output at pin 10 becomes positive when the Q output at pin 11 becomes negative. ..
The monostable period is set for about 1 second, as is the usual case. The induced line hum comes through C2, providing a continuous string of trigger pulses. The output becomes low for about 10 ms per second as the monostable times out and then retriggers. Diode D1 and capacitor C3 buffer the relay so it doesn"t chatter on those 10-ms pulses. Resistor R2 sets the sensitivity. ..
The 4047 is configured as a monostable multivibrator circuit or one shot that is set up to trigger on a negative-transition of the signal applied to its pin 6 input. The multivibrator"s on time is determined by the values of R1 and Cl. Although R1 is shown to be a 100-K unit, its value can be anything between 10 K and 1 MO. Capacitor C1 can be a nonpolarized capacitor with any practical value above 100 pF. By making R4"s value extremely high, the circuit can be.....
By vocalizing the numbers and symbols of its~eypad, the phone provides an audible confirmation that is useful to the blind. The serial-interface, 2 K-byte x 8-bit ROM (!C4) stores programmed sequences of instructions that are executed by the speech-processor chip IC2-manufactured by the General Instrument Corp. When you depress a key, tone-dialing chip ICl issues the corresponding number of pulses at its DP output. ..
This circuit uses an Amperex pyroelectric IR sensor, an LM324 op amp (configured as a high-gain amplifier in the..
Transistors Ql and Q2 control latch Q3 and Q4 to switch on the lamp. ..
The SillOO series circuit input is connected to a capacitive field sensor-possibly a piece of doublesided circuit board. Any induced voltage change on the plate is fed to the input of the peak detector section of the op-amp circuit. The Schmitt trigger monitors the voltage across the capacitor and changes its output state when the capacitor voltage crossed the 2.5-trigger point. ..
Only one LED can be on when the circuit is at rest. Which LED is illuminated is determined by the touch pick-up that last had human contact. Pickup terminal A controls the on condition of LEDl, and terminal B controls the on condition of LED2. ..
The project is designed to develop a touch sensitive switch to control any load. A 555 timer is used in monostable mode to drive a relay to switch ON a load for fixed time duration. The 555 timer is triggered by a touch plate connected to its trigger pin. The output of 555 delivers logic high for a fixed time interval as decided by the RC time constant connected to the timer. This output drives a relay which in turn switches ON the load for that duration after which.....
This circuit requires the bridging of two circuits to activate the electronic switch. That circuit does not require a 60-Hz field to operate and can be battery or ac powered. The two-pickup terminals can be made from most any clean metal; they should be about the size of a penny. The input circuitry of the two-terminal touch switch is a high-gain Darlington amplifier that multiplies the small bridging current to a value of sufficient magnitude to turn on Q3,.....
The main objective of this project is to develop a home automation system with a touch screen based control panel. As technology is advancing so houses are also getting smarter. Modern houses are gradually shifting from conventional switches to centralized control system, involving touch screen switches. Presently, conventional wall switches located in different parts of the house makes it difficult for the user to go near them to operate. Even more it becomes more.....
When someone touches the touchplate (TP), the resistance of his finger across points A and is added in series to the combination of Rl and R2, the capacitor C2 begins to charge. When the voltage across Cl is finally sufficient to fire NE1, Cl will begin to discharge. When NE1 fires, it produces a short between its terminals. Since R3 is connected across Cl, they are effectively in series after NE1 fires. A voltage spike will then be passed by C2 and this will act as a.....
In certain applications, such as transmitter or other communications and control applications, this circuit should be useful. Both audio output and dc control outputs are provided...
Operational Amplifiers
Computer Systems
Oscilloscopes
Transmitters & Receivers
Sensors & Detectors
ANSI Standards
Low Frequency Amplifiers
Power Amplifiers
Number Systems
Regulated Power Supplies
Analogue Filters
Digital Gates
