You enter the room, and suddenly light flashes, “alive” is a radio or a tape recorder. To make such a “miracle” the strength of the capacitive relay (the diagram in the figure).
allows you to quickly verify the health of the quartz resonators. Diagram of the device consists of a generator (T1), detector (D1, D2) and DC amplifier (T2). By connecting the quartz to the two terminals of the generator, the power on. If the resonator is OK, resistor R2 appears to the high-frequency voltage which is then fed to diodes D1, D2 for detection. Highlighted in this case a constant component opens the transistor amplifier stage. Load UPT serve milliammeter ИП1 and lamp L1. The glow lamp indicates the functionality of the quartz. But his activity is judged by the readings of the milliammeter. For the active resonator current is 70-90 mA, and for inactive — 30-40 mA.
There are electric circuits of high voltage sources for aeroionizatora, which are collected on the basis of the automotive ignition coil. They are all quite simple and easily repeatable. However, the cost of the ignition coil is very high.
Depressing statistic of the attacks on the secrets and the assets of the firms, organizations, entrepreneurs (and ordinary citizens) makes it necessary to take appropriate countermeasures, in particular, to acquire security devices and even systems. The proposed technical solution is one of them. Responsive to the appearance of outsiders (outsiders) in a protected area, this electronic guardian offices, apartments, warehouses and other premises in my own way belongs to the rightful owners and employees have “radiolocate” in the form of trinkets.
You love music, but not always have enough time and opportunity to go to the Opera or attend a concert. However, modern high-quality instrument sound allows you to “go” at the concert of your favorite artist and comfort of your own home. But before you buy such equipment, you need to know what requirements it must meet.
Currently, it has become fashionable household electrical lamps with shades. The publication describes this decoration to the lamp, which is easy to do it yourself from simple materials.
Enough next to your telephone to put a small plastic box, as from the speaker there is a loud voice. The secret here is simple: mounted in the box coil (scheme) “detects” the electrical signals of the phone conversation, coming then a three-stage transistor amplifier with low frequency.
Instruments based on the radio. Technical progress is relentless it forces us to buy all new electronic devices, and old, but usable receivers, tape recorders, record players and tape recorders had moved into the closets and attics, and then to the dump. However, enthusiastic Amateurs on a more careful attitude to an old technique, finding it different application. So old, no one needs a radio superheterodyne scheme can certainly be found almost any Amateur radio.
“Candle” — light bulb with a power of 50-60 watts. “Pistol” — a tube-tube in which is placed the photodiode, and the handle with the trigger button. The photodiode and the lamp are connected through the electronic circuit.
Many designs of metal collected with the use of electric welding. I made this several machines, and one was the most successful and easy to use. I offer welding transformer with electronic current control. It has no moving parts that require a high build quality and vibration. The control unit allows you to smoothly adjust the welding current by turning the potentiometer knob. At the same time all the range of the arc is burning stably. I think this design should be of interest to readers of the journal.