(Week5 - Week 6) Research on circuit

As salam..

Since Week4 is the Eid holiday..
I'm continued my research and testing the circuit in
Week5 and Week 6.. :)

As the previous post I had mentioned that my pulse
sensor is already failed in functioning.
This post will focus on the a few circuits that I had
done that is compatible to measure the heart rate
and pulse oximeter. So, I had make some research
about some circuits. Below is the first circuit that I
had tried that used Arduino programme.

Schematic circuit of Pulsometer

The Op-amp that used in this circuit is LM324.
IR led and LDR are used in this circuit.

LM324 is a 14 pin IC consisting of four independent 

operational amplifier (op-amps) compensated in a 

single package. Op-amps are high gain electronic 

voltage amplifier with differential input and a single-ended 

output. The output voltage is many times higher than the 

voltage difference between input terminals of an op-amp.

Theses op-amps are operated by a single power supply 

LM324 and need for a dual supply is eliminated. They 

can be used as amplifiers, comparators, oscillators, 

rectifiers etc. The conventional op-amp applications can 

be more easily implemented with LM324. Here are the
LM324 pin diagram and description. 

LM324

Pin diagram

Pin description

Below is the video that shows successful of the circuit.

As shown, there is working prototype that graphs pulses 

on computer that based on data from serial port. Work 

is going on signal processing to output pulse data, not only 

digital pulsations.

The goal is to build a separate digital/analog sensor for

arduino with possibility  to log data for future reference.

Below is the video of the result that I obtained from 

the schematic circuit that shown in early of this post.

As you can see the graph not stable like the one that
success. When I touched the LDR sensor, it gave the
shape of waveform. When I am not touched it, it became
a flat graph. I had tried to adjust the variable resistor,
but the result still the same.

When I'm looking on the serial monitor, the result in
analog supposedly about 400++ to less than 600.
But the number displayed is fixed to 1000
and that is when I'm not connected to ground.
When I'm connected to ground the reading is going
down to 0.

I'm also tried by change the sensor the LDR to the
IR transmitter and receiver. There is no result is
obtained.

Then, I'm proceed to try other circuit. That one will be
posted for the next post because I'm still in research
for the compatible with measuring heart rate and
pulse oximeter.