ECG simulator circuit is very useful in the medical community. Such as experimental research and development of bio-medical imaging. But this should not be taken with patients because we do not want that. The real purpose is that it is used to preview a heart rate only.
In general measuring the rate of heartbeat will get a waveform as Figure 1 start of all we take the sensor to Attached to on the patient at various points, Measurement results are amplitude approximately 1mV. A heartbeat rate is between 40 Hz to 150 Hz. electronic medical use of the letter P to the U of thousands of waves. ECG 1 times, be seen to one waveform clude the one peaks of spikes.
Figure1 the ECG waveform and feature of P to U
The working of circuit.
The circuit consist of two standard logic IC and a few parts.
IC1-CD4521 is CMOS is called that 24 stage binary counter, by have the frequency setting in counter is X1- crystal at frequency 4,194,304 Hz.
The IC1 will divide frequency out of 16 Hz is square wave to output Q18 (pin 10).
The switch S1b is optional, the output frequency of IC 1 is a low frequency of 1 of 2 Hz.
The Q8-pin output frequency of 16 Hz will connected as clock signal to IC2. Which is a Decimal Counter circuit at pin 15 of IC2 to divide frequency at output 10.
The second signal will be filtered with R3 and C3 are waveform in spikes in to pin 15 of IC2. The D2-diode will block negative voltage not flow in to pin 15
IC2 will count to 9 and will be on hold state. Then, pin 11 is connected to pin enable input is pin 13 will reset working. Which is the wave conditions in the U.
Also a device output signal of Q1, Q4 and Q6. By the first wave is a pulse that has been transformed into a P wave form, by filter in integrator form by R6 and C4, so C4 will be charged from 0V to about 1V.
The T wave form of the integrator ofR7 and C4, where R7 is the resistance less than half of the R6. Wave pulses of Q6 will charge more by C4 is 2 times of the P waveform. C5 and R10 are put into a R pulse between 2 waveform.
The R8-resistor to limit the current to the charging of C5, and in at same time D5 to allow the voltage to 3.8V via the C R9 and D3.
Which is LED blinks while the R-waveforms. Which the spike waveform passed R13, R14 and R15 will convert the output voltage is 1V and 1mV needs. This circuit use the 9-volts battery The rate of consumption of the circuit about 2.5mA.
How to builds
To begin with Make the PCB as PCB layout in Figure 3, secondly then to assemble all parts in to the PCB as Figure 4 , then check all for errors after assemble them. Next connect the wiring to the oscilloscope and the battery wire to the circuit. Just now already to use ECG simulator.
The component List
Resistors 0.25 W 5%
R3, R4, R12: 100K
R13, R14: 10K
C1: 82pF 50V, Ceramic
C2: 22pF 50V, Ceramic
C3: 0.22uF 63V, Polyester
C4: 0.47uF 63V, Polyester
C5, C6: 0.33uF 63V Polyester
C7: 0.1uF 63V Polyester
D1, D2, D4: 1N4148 0.75A 100V_Silicon Diode
D3: LED_in Super bright type
D5: Zener Diode_3V 500mw
IC1: CD4521__CMOS 4-stage Frequency Divider
IC2: CD4017__DECADE COUNTER/DIVIDER IC
S1: Slide switch in DPDT – Double – pole , Double-throw.
BT1: 9-volts battery
X1: Crystal__4.194304 MHz
Example: ECG simulator
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