SU107868A1 - Single channel electrocardiograph - Google Patents

Description

The subject of the invention is a single-channel AC-UKCP-1 electrocardiograph for recording incoming to the amplifier through a switch from several leads of the heart biocurrent to a perforated photo-tape.

A distinctive feature of this electrocardiograph is the automatic stopping of the photo tape. After briefly pressing the start button of the tape mechanism, recording is performed for 3.6 seconds, after which the tape mechanism automatically turns off. This is because the power supply circuit of the electric motor of the tape mechanism is conducted through a contact that automatically opens this circuit at a predetermined number of revolutions of the electric motor.

This event allows you to record all leads on the tape of the same length, which plays an important role in comparing records.

It is also possible to obtain longer recordings on a tape of arbitrary length.

The invention allows, in addition, to produce lead names and patient numbers automatically during the recording process; AC calibration, which eases the standard sensitivity setting; automatically applying a calibration signal during the recording of each lead.

FIG. 1 shows a general view of the apparatus. On the upper front panel of it there are power supply and receiving cassettes and handles, switches, switches, buttons and other controls, adjustments and control devices are located.

Here: 1-case of the device; 2-hose supply; 5-wire ground; 4-grounding bracket; 5 extension cable; 6 electrodes for limbs; 7- chest electrode; 8- rubber bands.

FIG. 2 shows the circuit diagram of the JM 107868-2 device. Amplifier of the slugs serves to amplify weak, of the order of a millivolt, electrical signals from the electrodes superimposed on a person, and consists of three stages on electronic tubes. The first two stages on the lamps L and L, the third on the lamps L and L.

The connection between the cascades is carried out through separation capacitors Sb, Sb, Cj and Cz, and the leakage of the grids, RIQ and Rn Amplifier is made according to the differential circuit. Such a scheme provides the ability to significantly reduce the amplitude of network crosstalk on the record.

Attenuation by common-mode signals is achieved by introducing into the cathodes of the lamps of the 1st and 2nd stages sufficiently large resistances R and, due to which there is a strong negative feedback due to signals brought to the grids and phase, and the same amplitude with respect to zero wire amplifier. For maximum attenuation of the common mode sensitivity, a potentiometer Rz was inserted into the anode circuits of the 1st stage, which allows equalizing the gain of the common mode signal by the shoulders of the common mode signal.

The sensitivity is adjusted at the input of the 3rd cascade by dual potentiometers. A variable resistance 1h is connected to the cathode circuits of the lamps of the 3rd cascade. A change in the magnitude of this resistance changes the magnitude of the negative feedback in the 3rd stage, and hence the sensitivity of the whole amplifier.

The background compensator is connected to a 6.3V winding of the Tpi transformer. The middle point of the winding is connected to the neutral wire. From the background compensator, the compensation voltage is applied to the resistance RH. In order to enable the output voltage to compensate, a mountain of voltages of different phases and amplitudes are used to equip the compensator circuit with potentiometers Rz and.

The power supply device includes a Tpi power transformer, a rectifier on the Kenotron Lt, a constant voltage regulator on gas stabilizers // 5 and Lev, a filament current regulator for lamps of the 1st and 2nd cascades on the 0.42 B5.5-12 booster ( L).

The network winding of a power transformer has taps for the possibility of connecting to networks of different voltage BUT, 127 and 220 V. The transformer is switched to different voltages by the switch / 7i. The electric motor M is connected to the 110-volt winding of the transformer.

The DC voltage rectified by the Kenotron L and filtered by the C / i capacitors is used to power the anodes of the L and L lamps of the terminal stage. The screen grids of the final stage are fed through voltage resistance from the stabilolovolta L (SG-4C). The anodes of the lamps of the 1st and 2nd stages are supplied with voltage, stabilized by two gas stabilizers L and L, through the filter, a part of the voltage after the filter, removed from the resistor / parallel connected and the capacitor Cz, is introduced into the grid circuits of the cascades.

The power of the filaments of the lamps of the amplifiers and the kenotron is carried out by alternating voltage taken from the winding of the power transformer 2-3-O-4. Lamps of the 1st and 2nd stages are powered by a current stabilized by a Barretter 0.425B 5.5-12. Anterior resistance is included in series with baretter. Resistance is used to set baretter mode L.

The voltage taken from the resistance connected in series with the barretter is fed through the calibration button K. or the automatic calibration / C contacts to the primary winding of the calibration transformer Tr2. A calibration voltage having a double amplitude of 1 millivolt is removed from the divider included in the secondary winding of Trz and is fed into the circuit of one of the catalysts of the first stage.

The calibration voltage setting is made by variable resistance. When recording electrocardiograms, lead names, patient numbers and calibration are automatically recorded. When the trigger button of the tape mechanism is pressed, the ratchet wheel is rotated at a certain angle. Holes are made in the ratchet wheel. In the process of turning the wheel, the light from the numerator lamp, for some time passes through the condenser lens to the patient numbers and the names of the leads placed on the edges of the mechanism disks. Objective lens numbers are projected on a stationary paper. A disc with lead numbers using flexible shaft and bevel gears is connected to the axis of the lead switch. Therefore, translation of the disc with the names of the leads is carried out simultaneously with the transfer of the handle of the switch of the leads.

Claims (3)

1. Single-channel AC-powered electrocardiograph that records microcurrents on a moving perforated photo-tape, driven by an electric motor, coming from several leads connected to an amplifier through a switch, characterized in that, to ensure that all leads are recorded on the tape of the same length without the operator’s fate, the power supply circuit of the electric motor of the tape mechanism is conducted through a contact that automatically opens this circuit after a specified number of revolutions ektrodvigatel. 2. The electrocardiograph according to claim 1, characterized in that, with the simplification of the service, discs are used that are controlled by a start button and carry patient and lead designations projected onto a photo tape. 3. The electrocardiograph, PP, 1 and 2, is connected with the fact that the DoT of the automatic application of the calibration signals to the moving photo tape is a contact that is short-circuited during the recording of each lead and serves to connect the primary winding of the calibration transformer, the secondary the winding of which is connected to the cathode of the first carcass of the amplifier, to the resistance connected in series with the barette in the AC circuit. - 3 - # 107868 Subject invention