|
Arabic
Bengali
Chinese
English
French
German
Hebrew
Hindi
Italian
Japanese
Korean
Malay
Polish
Portuguese
Spanish
Turkish
Ukrainian
Vietnamese|
ENCYCLOPEDIA OF RADIO ELECTRONICS AND ELECTRICAL ENGINEERING Two designs with touch control. Encyclopedia of radio electronics and electrical engineering
Encyclopedia of radio electronics and electrical engineering / Beginner radio amateur Among radio amateurs, touch-controlled designs are popular, allowing you to turn on or off certain loads by touching a metal plate with your finger. Today we will introduce two such devices. SENSOR SWITCH The touch switch on CMOS microcircuits was described in the article by M. Kutsev "Sensor switch"in "Radio", 1999, No. 7, p. 50. A similar device is not difficult to perform on TTL microcircuits (Fig. 1). They can turn on or turn off an incandescent lamp. Of course, this design is just a demonstration aid, although it is suitable for use, say, in emergency lighting of a living space or lighting a "utility room".
When a finger touches the sensor plate E1, the interference signal of the human body is amplified by a cascade on a composite transistor VT1VT2. A low-level pulse is formed on the load resistor R1, which starts a waiting multivibrator, made on the elements DD1.1 and DD1.2. The multivibrator generates a low-level pulse, the duration of which depends on the capacitance of the capacitor C1 and the resistance of the resistor R2. With the ratings of these parts indicated in the diagram, the pulse duration is approximately 0,5 s. From the output of the multivibrator, the pulse is fed to the input C of the DD2 microcircuit - a JK flip-flop operating in the input pulse counting mode. For each negative voltage drop, the trigger changes its state to the opposite, i.e., pin 8 will alternate between high and low. This leads to opening or closing the key on the transistor VT3, which means turning on or off the incandescent lamp HL1 (MNZ, 5-0,26). Capacitor C1 - K50-35, C2 - K10-7v or other ceramic. Resistors - MLT. During installation, pins 2-5, 9-11, 13 of the DD2 microcircuit can be left unconnected, but to increase the noise immunity of the device, it is better to combine them and connect them to the power plus through a resistor with a resistance of about 1 kOhm. To power the device, you can use a mains stabilized power supply or a battery of galvanic cells with a voltage of 4,5 V. GENERATOR WITH TOUCH SWITCH A feature of this design (Fig. 2) is the ability to turn it on and off with one touch of sensors E1, E2. It can be used, for example, as a simple security device. To do this, it is enough to connect the E1 sensor plate with a piece of mounting wire to some metal object, for example, to a door handle. It is worth touching it - and the dynamic head BA1 will emit an alarm signal.
The device uses only one CMOS chip. On the elements DD1.1 and DD1.2, an RS flip-flop is made. Its state is changed by touching the sensor plates. Resistors R3, R4 protect the trigger inputs from static electricity. On the elements DD1.3, DD1.4, a 3H generator is made. The frequency of its oscillations is changed by a variable resistor R7. The signal from the generator output is fed through the limiting resistor R8 to the base of the transistor VT1, on which the power amplifier is assembled. The load of the amplifier is the dynamic head BA1, the resistor R9 limits the current through the transistor. When the trigger is in the zero state, i.e., there is a low level at pin 3 of the DD1.1 element, the generator does not work. Now it is worth touching the sensor plate (or door handle) E1, as the trigger will go into another state under the influence of electrical pickups. The high-level signal will go to the input pin 9 of the element DD1.3. The generator will turn on, the dynamic head will make a sound, the tone of which depends on the position of the variable resistor engine. Turn off the generator by touching the sensor plate E2. It is permissible to use any transistor of the KT315 series in the device, a variable resistor - SPZ-46, the rest - MLT. Capacitors - K10-7v, dynamic head - 0,5GDSh-2 with a voice coil with a resistance of 8 ohms. Instead of a head, you can use a capsule of the DEMSH type with a winding with a resistance of 180 ohms. Resistor R9 is excluded in this case. The device is powered by a stabilized source, a rechargeable battery or a battery of galvanic cells. In standby mode, the current consumed does not exceed a few microamperes, and in operating current reaches 50 mA. If, when connecting the E1 sensor plate to a metal door handle, which together with the connecting wire is a source of electrical interference, a false operation of the device will be observed or the generator will not turn off when the E2 plate is touched, it is necessary to reduce the sensitivity of the E1 sensor circuit. To do this, it is enough to install a resistor R1 of lower resistance or turn on a variable resistance of 4,7 MΩ instead (for example, SPZ-9b, by moving the engine of which it is easy to select the desired sensitivity of the machine. Author: E. Mukhutdinov, Novy Tikhonov village, Volgograd region
Traffic noise delays the growth of chicks
06.05.2024 Wireless speaker Samsung Music Frame HW-LS60D
06.05.2024 A New Way to Control and Manipulate Optical Signals
05.05.2024
▪ Miniature neural networks of the brain are grown ▪ The most distant object in the solar system discovered ▪ 8051 IP cores are 15x faster ▪ Philips key019 keychain camcoder ▪ Highly efficient electrocatalyst for clean energy
▪ section of the site Car. Article selection ▪ article Down with weapons! Popular expression ▪ What metal is liquid at room temperature? Detailed answer ▪ article Spreader of patterns (spreader-shoveler). Standard instruction on labor protection ▪ class B triode amplifier. Encyclopedia of radio electronics and electrical engineering ▪ article Fingerprints - how to make them visible. Chemical experience
Home page | Library | Articles | Website map | Site Reviews
www.diagram.com.ua |
See other articles Section 
Latest news of science and technology, new electronics:
All languages of this page