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Hi,
it was more than 1 year ago, hard to remember :) , I switched my application to use SPI (because of hardware support) and got it working. I was not able to find a cause with bit banging approach.
Thank you for response! System measures heart beat 0.5Hz-5Hz. Is it too low to include it ,isn't it. it shouldn't change anything in phase margin.
Phase margin for noninverting is 180-100=80 and buffer's 180-110=70. Is it enough for op amps in my system be stable during the whole time? I...
Hello,
I would like to find out the stability of the circuit of an op amp ( OPA2340). I included phase/gain characteristics and the circuit. It's connected as a buffer and non inverting.
For non-inverting:
Gain=3.3. Feedback factor F=0.23. K=20log(0.23)= -12.77dB
Gain 0db crosses at around...
Im working with RFM12B and MSP430. SPI - bit banging and module as transmitter. All i want to manage is to get nIRQ high after i read status command (0x0000) and as response 0x4000 -> Spi is workinG.
When i send the status command (0x0000) , the response is 0xA100 always and IRQ is low...
Re: SpO2 circuit: how to determine the suitable clock pulse for LED?
The heart rate is 0.5Hz - 5 Hz. Sampling frequency should be at least 2x more (The Nyquist Sampling Rate). Ive been working on Spo2 reading, led changing frequency is 1kHz (1 ms) => 1ms IR LED ON, 1ms R LED ON.
I'm working on the problem today. I went back to my experimental schematic which is this :
P1.1 and P1.2 are turn off/on every 1ms. ( P1.1 ON/P1.2 OFF (1ms),P1.1 OFF/P1.2 ONN(1ms), P1.1...). DAC is constant voltage.
Oscilloscope shows the output.
When i connect it with LM358 and NPN transistor...
It's working but it's slow.I switch 2 LED's every 1ms. How could i improve the speed ?
It was working nicely when i connected DAC output to the LED's cathode and PIN output to the LEDS anode. Pin output switched every 1ms, output on photodiode was good as expected. That was not properly...
Thx keith, you helped.
I tried your suggestion before with wrong calculation,therefore i abandoned it. :???:
I can't lower R because it would result in higher current. 47ohms set limit to 24mA.
Which transistor is fine for this application in to/dip package (on breadboard)?I'm limited in...
Re: LED driving with DAC
Thx, i was playing with leds in Circuit Maker,accidentally changed LEd to Blue. I use only RED/INFRAREd which got Vf max 1.7V. The led in this circiut got Vf=1.7V.
Do you think it will work if P1.0 is pin output which should turn on/off the LED and DAC drives LED...
I drive LED with DAC from microcontroller because i want to adjust the brightness of LED.
I simulated the connection on the image in Circuit Maker and LTSpice,it doesnt work with 3.3v on the LED (v2). with 5/6.6v works as it should. My microcontroller supply is 3.3V.
Any other ideas how to...
ive red few articles about oximeter , I assembled the schematic which i attached here (ox_1.png).
It's working but i get strange results after i compared it to other people's results.
Red LED output and INFRA red output in attachments.
Red LED peak wavelength 660nm and infra 940nm which is...
Hey i searched for oximeter but this problem hasn't occured on the results.
I build my own sensor using 2 LED's and photodiode. Connected as in schematic attached (one change -> the differential op amp got right now gain only 1 because i dont have any resistors left ).
Im reading the signal...
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