Diagram Guide

Showing posts with label gate. Show all posts

Wednesday, October 29, 2014

Light Gate with Counter Circuit Diagram

The circuit described here counts the number of times that an infrared beam is interrupted. It could be used to count the number of people entering a room, for instance, or how often a ball or another object passes through an opening (handy for playing shuffleboard). The heart of the circuit consists of you guessed it a light gate! Diode D1 is an IR diode that normally illuminates IR transistor T1. The light falling on T1 causes it to conduct to a certain extent. The resulting voltage on the collector of T1 should be just low enough to prevent the following transistor (T2) from conducting. This voltage can be adjusted within certain limits using P1.

Circuit diagram :

Light

Light Gate with Counter Circuit Diagram

As soon as an object comes between D1 and T1, the light shining on T1 will be partially or fully blocked, causing the IR transistor to conduct less current. As a result, the voltage on its collector will increase, producing a brief rise in the voltage on the base of T2. This will cause T2 to conduct and generate a negative edge at IC1. This negative edge will trigger the monostable multivibrator, which will then hold the output signal on pin 3 ‘high’ for a certain length of time (in this case, one second). Atthis point, two things will occur. First, a buzzer will be energised by the output of IC1 and produce a tone for approximately one second. When the buzzer stops, a negative edge will be applied to the clock input of IC2, causing the counter in IC2 to be incremented by 1. IC2 is conveniently equipped with an internal binary-to-BCD decoder, so its outputs only have to be buffered by IC3 and T3 to allow the state of the counter to be shown on the 7-segment display. Switch S1 can be used to reset the counter to zero.

If a one-second interval does not suit your wishes, you can modify the values of R3 or C1 to adjust the time. Increasing the value of R3 lengthens the interval, and decreasing it naturally shortens the interval. The same is true of C1. When building the circuit, make sure that T1 is well illuminated by the light from D1, while at the same time ensuring that T1 ‘sees’ as little ambient light as possible. This can best be done by fitting T1 in a small tube that is precisely aimed toward D1. The longer the tube, the less ambient light will reach T1. The sensitivity of the circuit can be adjusted using P1.

Author : T.Hareendran - Copyright : Elektor

Thursday, August 28, 2014

Simple Gate Alarm

Description:
A cheap and simple gate alarm made from a single CMOS Integrated Circuit.

Figure 1 represents a cheap and simple Gate Alarm, that is intended to run off a small universal AC-DC power supply.

IC1a is a fast oscillator, and IC1b a slow oscillator, which are combined through IC1c to emit a high pip-pip-pip warning sound when a gate (or window, etc.) is opened. The schema is intended not so much to sound like a siren or warning device, but rather to give the impression: "You have been noticed." R1 and D1 may be omitted, and the value of R2 perhaps reduced, to make the Gate Alarm sound more like a warning device. VR1 adjusts the frequency of the sound emitted.

IC1d is a timer which causes the Gate Alarm to emit some 20 to 30 further pips after the gate has been closed again, before it falls silent, as if to say: "Im more clever than a simple on-off device." Piezo disk S1 may be replaced with a LED if desired, the LED being wired in series with a 1K resistor.

Figure 2 shows how an ordinary reed switch may be converted to close (a "normally closed" switch) when the gate is opened. A continuity tester makes the work easy. Note that many reed switches are delicate, and therefore wires which are soldered to the reed switch should not be flexed at all near the switch. Other types of switches, such as microswitches, may also be used.

Sunday, August 17, 2014

Pulse generator circuit with Logic Gate

Pulse generator circuit above is a pulse generator that uses logic gates. There are so many types and variations that can generate a series of pulses.

The simplest is the use of transistors or often called a flip-flop. There also are using integrated circuit such as IC 555. Theres more to exploit the resonance of the capacitor and inductor relationship as oscillators. To be sure whatever form and whatever the circuit components used must be able to generate electric waves which have a peak voltage (logic 1) and valleys (logic 0) is continuous.

Any variation of pulse generator circuit design has advantages and disadvantages of each, just how your decision for the appropriate circuit. For example to create a clock signal for a simple utility that you can only take advantage of the transistor but if you need a more accurate clock signal and form a perfect balance you can use IC Astable or logic gates. Or perhaps you need a signal with very high frequency (up to MHz) you can use a combination of inductor, resistor and capacitor.

Frequency value of the pulse generator circuit gate above is determined by the value kapaitor C2, R2, R3 and VR2. The greater the value of these components will lower the frequency and vice versa. Actually nothing is difficult to make a series of pulse generators, almost all time-based series is utilizing the nature of the charge and discharge capacitor. Therefore, like any form of variations in pulse generator circuit, always have a larger capacitor value will make the frequency produced smaller or longer periods of time, sedangkaan smaller capacitor values will result in greater output frequency.