Automatic devices that produce sound and light signals, are widely used in various designs and models. Usually auto-switch performs the multivibrator, the control of sound or light emitter (call, dynamic head, incandescent, etc.). These devices contain more transistors and a dozen resistors and capacitors.
Generator signals that we offer to our readers, has a minimum number of parts, easy to manufacture, requires establishing. It can be used as an alarm clock in digital clocks, time relays for color printing, a “caretaker” for car, alarm of stop of the tape recorder.
The device is implemented on a single chip К155ЛА8 (К1ЛБ558) using the transistor КТ315Б and led АЛ102 or АЛ307 (Fig. 1).
The generator produces rectangular pulses with a frequency of about 800 Hz. With the same frequency of the led flashes, but visually the eye perceives continuous illumination.
Fig. 1. Schematic diagram of svetasvatara
Fig. 2. Schematic diagram of the generator with an intermittent signal
Fig. 3. The circuit Board svetozvukovye with location details
Fig. 4. Printed circuit Board with the location details generator previewsly signal
The sound source is a microphone capsule of DEMS-1.
Operated device at the input X1.
If the scheme is a little harder, get an intermittent sound like a telephone busy signal. To do this, add a second generator with a frequency of 1-2 Hz, which controls the operation of the first (Fig. 2). The desired frequency of parcels matching set size of capacitor C1.
Instead К155ЛА8 (К1ЛБ558) you can use the chip К133ЛА8 (К1ЛБЗЗ8), and instead КТ315Б transistors КТ315В, КТ315Г, КТ315Е, МП37, КТ342Б — КТ342Г. The microphone capsule of DAMS-1 can be replaced by a high impedance earphone.
The second device (of the robes. 2) in order to avoid interference, it is desirable to feed from a separate source.
The printed circuit Board both generators are presented ka figures 3, 4.
R. LYAKHOVSKY, Odessa