Reflexology block. Encyclopedia of radio electronics and electrical engineering
Encyclopedia of radio electronics and electrical engineering / Electronics in medicine
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The reflexology unit acts as a generator of reflex impulses. It consists of a square-wave generator and a power amplifier.
The generator of rectangular pulses DD1 is implemented on the timer IC KR1006VI1, included according to a typical circuit. In the "inner" position switch SA3, the generation frequency is determined by the value of the multi-turn trimmer R9 and capacitor C4 and ranges from 10 to 20 kHz. In the "external" position switch SA3, the generation frequency is determined by the value of the sliding variable resistor R11 and capacitor C4.
The voltage from the generator output (pin 3 DD1) is fed to the input of a power amplifier implemented on transistors VT1 (KT829A) and VT2 (KT315A). The collector circuit of the transistor VT1 includes a transformer T1, for the manufacture of which a core Ш10x9,5 mm is used. The primary (I) winding contains 500 turns of PEV-1 wire, 0,23 mm in diameter, and the secondary (II) winding contains 3000 turns of PEV-1 wire, 0,1 mm in diameter. The voltage at the output of transformer T1 at a load of 1 MΩ is at least 50 V (rms) at a frequency of 10-20 kHz. Switch SA2 is used to switch the output signal level. The parameters of the voltage divider R6-R7 are selected based on the minimum voltage at the output of the block (at the request of the performer).
With a possible repetition of the design of the device, it is desirable to provide for the possibility of smooth regulation of the voltage at the output of the unit.
Non-standard 5-pin connector XS1 is used to connect external remote devices.
The circuit diagram of the reflexology unit is shown in the figure.
(click to enlarge)
The P1 indicator, together with the VD1 ... VD4 bridge, serves to evaluate the output current. The circuit uses a pointer indicator type M4248 with a sensitivity of 0-100 μA, with a frame resistance of 2750 ohms. Switch SA1 is used to change the measurement limits P1 to 5 (or 10 mA). Resistor R1 multi-turn type SP5-3. The VD6 LED is used to indicate the voltage at the input of the power amplifier. The DA1 chip (78L05 type) is a +5 V supply voltage regulator. The XS2 socket (DJK-07 type) is used to connect an external power supply. Schottky diode VD7 (type 1N5717) serves to protect the circuit from erroneous connection to a power source of a different polarity. Switches SA1...SA4 - sliding type PD-9.1. Most fixed resistors and capacitors are packageless, size 1206. All elements are placed on two printed circuit boards with dimensions 46x94x1,5 mm (carrier) and 46x50x1,5 mm.
The appearance of the reflexology unit from the installation side is shown in the figure.
The reflexology unit can function both in autonomous mode and when controlled from the main unit. In this case, the reflexology unit is connected with a 3-wire cable through the XS3 connector (SKH-3.5-30 type) to the XS2 connector of the main unit. Management is carried out on the output. 5 chips DD1.
The scheme of the reflexology block does not require special adjustment. Correctly assembled block works immediately. The process of setting up the device is reduced to the selection of capacitor C4 and resistor R9 in order to obtain a frequency of 10-20 kHz of the generator and the selection of the value of resistor R3 in order to obtain the maximum voltage at the output of the device. Control is carried out using standard measuring instruments - an oscilloscope and a frequency meter.
When setting up the unit, sometimes it is required to select the values of the elements marked on the circuit diagram with an (*) icon.
The current consumption of the reflexology unit depends on the used output load. At a power supply voltage of 9 V and when using "regular" remote devices, it is not more than 150 mA.
The appearance of the reflexology unit is shown in the figure.
The device is housed in a plastic case. Housing dimensions: 48x97x24 mm. Weight, no more than 130 g.
Literature
- Treister R. Amateur radio circuits on IC type 555. Per. from English. -M.: Mir, 1988.-263 p.
- ADG428/ADG429 LC2MOS Latchable 4-/8-Channel High Performance Analog Multiplexers. Prospectus of Analog Devices, Inc., 1999. -12 p.
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