Change arrow indicators the dog often come led. And this is not surprising: the second is much easier and safer first. Simple five-level scheme of the AF voltmeter to the voltage of 0.1—0.6 volts, where the indicators are LEDs, published in the journal “Рипката1ег” (GDR). If the signal fed into socket x2, XS, the voltage exceeds 0.1 V, open transistors V2, V4 and, as a result, the led turns on Q1. With an increase of the signal to 0.2 In open semiconductor triode V6 and the led flashes B2. When the signal voltage reaches about 0.6 V, burn all the LEDs.
A FIVE-LEVEL VOLTMETER
Recently, widespread quartz alarm clock made in China, characterized by a relatively high ring volume and cheapness. If the watch is out of order, but the alarm clock still works, it can be used in a variety of makeshift structures. For example, the proposed indicator of a bite.
Protection of your house and garden from small rodents, insects relevant today. Various industrial devices “repellents” are on sale, but this same device is able to produce hams with a medium level of training. Unlike many schemes of such devices listed below are quite original. Known schemes are based on the ultrasonic frequency generator (uzch), “loaded” to the piezoelectric capsule. The frequency of these generators can be tailored (adjusted by changing the values of the RC circuit), but it is invariant under the operation of the device, and therefore of the generator. That is, any rodents, insects, birds or animals would not be “programmed” generator uzch (all of these entities are afraid of the discomfort of pulses of a certain frequency), over time, the device ceases to be effective due to rodents or insects exposure.
In the Food program of the USSR much attention is paid to food production in farmlands and suburban areas. A contribution to this important cause made the young Amateurs of RCUT of the Kazakh SSR. They prepared and tested a number of automatic devices that will help to grow agricultural products. The developers sought to create devices that are available for repetition at home. Oki have sufficient accuracy (±5-10%).
The water treated by an electric current, acquires new properties: some of it manifests itself as a weak alkali solution and the other acid. When activated in this way the water felt on animals and plants, it was found that the liquid with alkaline properties were the stimulator, and one that bears signs of acid inhibits the growth of microorganisms and cells of living tissue.
Records of poultry ka large poultry farms and in the farms is no easy task, without automation is not enough. This operation can be performed using the microcalculator B3-23. It is necessary only to add the connector through which the electronic device is connected to the sensor (see Fig.) — associated with a movable strip contact pair S1 (see diagram). 
The magazine “Amaterske Radio” (Czechoslovakia) proposed scheme is a simple audio probe to detect logic levels; low (logic 0) and high (logical 1). The device consists of a bitonal multivibrator, is made of two elements of D1.1, D1.2 chip D1, and two keys, collected three transistors V2—V4 (see circuit diagram).
For school discos and Amateur recording magazine “Funkamateur” (GDR) offers a scheme of five “anal stereomixer (Fig. 1). It is designed to connect two stereophonically (X1, x2), two stereos, (XS, X4) and one microphone (X5) for a soloist or a master program.
It’s tempting to assemble a simple Telegraph device and to communicate using Morse code. Reliable two-way communication is needed in the conduct of military sports games and competitions, in a tourist campaign and in summer camp, it is interesting to set it up at home or at the cottage.