Using modern element base, it is possible to simplify the structure generators, performing the role of signaling in various devices. About this it is told in the article.
One of the main elements of simple generators, alarms - audible emitter. All the proposed designs used electromagnetic the capsule imported with a diameter of 12 mm at a working voltage of 6 V with built in generator. The capsule keeps working at a lower voltage to 1 V. When the supply voltage on it 6 In (subject to the polarity!) hear a relatively loud sound has a frequency of about 2000 Hz.
Even in the flashing led light with a diameter of 8 mm red color glow brightness 800 MCD. Including it in series with the cap (Fig. 1), get the simple oscillator-detector. Submitting to such a site feed the voltage will hear intermittent beeps. The current consumption of the device during signal is about 15 mA.
If a slight decrease in volume due to the voltage drop across the led not satisfied, you can collect the generator using a field-effect transistor (Fig. 2). Until the led is turned on, the voltage across the resistor is small and not enough for opening the transistor. At the outbreak of the led, the voltage across the resistor reaches 4 V, the transistor opens, the capsule begins to operate at maximum the volume, since the voltage drop across the transistor at a current of 20 mA is not exceeds 50 mV. On the findings of the cap there are no impulses of self-induction, so to install the protective diode, as is done in similar stages with normal primer, no need.
In Fig. 3 shows a diagram of oscillator control voltage input. So, when you move an engine tuning resistor R1, the voltage at the base transistor VT1 will be less than 0.6 V, it closes. But the transistor will open VT2, primer BF1 and HL1 led will start to work.
This generator can be used, for example, a sound signalling device short circuit, described in "Radio", 2001, № 10, p. 58, is host to chip. The indicator will now light and sound.
With the specified primer will be able to build a simple switch phone calls (Fig. 4) or just call for a telephone set. When you receive telephone ringing alternating voltage is rectified by a diode bridge VD1, then the rectified voltage is smoothed by the capacitor C2 and limited by the Zener diode to a safe for the capsule voltage. If the Zener diode to replace three series LEDs CIPD included consistently, during the call they will glow.
Simple sound-and-light photosensor can be collected according to the scheme shown in Fig. 5. While the illumination of the photodiode VD1 sufficient field-effect transistor VT1 is closed, generator similar scheme has been presented in Fig. 2, works. When the illuminance of the photodiode becomes less than the threshold voltage at the gate of the transistor VT1 increases. Once it exceeds about 1.5 V, the VT1 transistor opens, the generator will turn on. Appears sound from the capsule and the led flash.
If you swap the resistor R1 and the diode, the generator will turn on when increasing the illumination of the photodiode to a predetermined value. Necessary the sensitivity of the device set selection resistor R1.
The device is assembled according to the scheme in Fig. 6, similarly to the preceding, but is controlled using the touch plates E1 and E2. While the resistance between them is large, the generator-detector is not working. But it is necessary to touch the plate with your finger as the resistance between them will fall, will open the VT2 transistor, turns on the generator. The VT1 transistor operating in the avalanche mode, performs the role of Micropower reference diode and protects the field effect transistor VT2 discharges from static electricity.
The devices collected by the schemes in Fig. 2-6, it is permissible to use the resistors MLT-0,125, oxide capacitors K50-35, K50-16. The capacitor C1 in Fig. 4 - type K73-17, MBM; C1 in Fig. 6 - K10-17. Instead of the photodiode will fit any FD another, designed for the infrared range, for example, FDA, FD-LC, FD-CP. Flashing led can be replaced by any other similar, suitable by the color of the glow and size, and a diode bridge CCA (see Fig. 4) four diodes series CD, CD, CD. Instead of field-effect transistors KV (Fig. 7,a) it is acceptable to set the current keys KRKA (Fig. 7,b), and is listed on the scheme of bipolar transistors - any low-power silicon structures n-p-n, for example, the series CT.
Earpiece with built-in generator can be any other of this series with index X. the First two digits in the designation is the diameter of the case, the two last - maximum operating voltage. After the acquisition of the primer do not forget to remove closing the hole self-adhesive label.
If any of light and sound generators will be embedded in another the device, preferably on a circuit to set at least one locking capacitor 0,15...100 UF. This will prevent a negative impact embedded generator to any circuit design.
Author: A. Butov, S. CORBA Yaroslavl region