Signaling device for emitting sound or light alarm, uses the principle of capacitive relay. As can be seen from the diagram in the figure this relay consists of a generator on the transistor T1 and a single stage amplifier transistor T2. The generator operates at a frequency of 760 kHz. On the same frequency configures the circuit (L1, C1, C1'), inductively coupled with the generator circuit (L2, C2) and called suction. Coils of the two circuits of the flat wound on ferrite rods. The coil L1 has 100 turns of wire LASO 7X0,07, coil L2 28+ +23 turns of the same wire.
For extracting the contour of the need to take minimum values of the capacitors and to select a desired value of the inductance L1. This condition is necessary to ensure that the capacity of the person relative to the ground has had a significant impact on the detuning of the circuit. An exhaust circuit for this purpose is connected a piece of copper foil, forming a plate of the capacitor, the capacitance of which changes as you move your hands to him man. In this case there is a change in the resonant frequency extracting circuit, it ceases to take away the energy from the oscillator circuit.
The H level In voltage generator circuit will increase and through a coupling capacitor C, the voltage will fall on the detector D1. Predetection the voltage across the resistor D4 governing its amplitude, is fed to the base of transistor T2. The transistor must be high frequency and have low input capacitance. The capacity of the coupling capacitor C7 is selected experimentally so that the relationship between these cascades was reliable but not very large.
The load transistor T2 serves as one of the windings of polarized relay R. as soon As the current through the MOSFET reaches the current value of the relay (0.8 to 1 mA), the latter their contacts includes actuator - siren or light a warning light. The other winding is used to lock a signal.
The described device was used for the protection of the car.
Instead of transistors AS and you can use 156NU70 KT361 and KT315, instead of the diode 1NN41 - DJ. Relay you can use RP-4, passport U.
Literature
- "Amaterskt radio", 1967, No. 2.
- Radio No. 9, 1967, p. 61.
Publication: N. Bolshakov, rf.atnn.ru