Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.
i tried your design... but i think there some problem
1. i am not able to see any changes in output.
2. this may be due to the gain is 1. but i connected the resistor of 100K between pin 7 & pin 6. but no result.
i have made this design please tell me is this correct to get the output... i have not included any filter for now, but i seen some waveform yesterday using this design but i think it was some thing else. because i am not getting any clear result now...
Why do you keep changing the opamp and power supply voltage?
The gain of your latest circuit is 11 times and it has a dual polarity supply.
The output of the opamp should go positive or negative depending on the amount of light on the LDR.
I got this output waveform, Do you think i will get the pulse rate after including a band pass filter of 1Hz to 3Hz. since now its giving 50.xx Hz.
i am using the above LED & LDR pair.
Please refer the images
The article explains that the differential amplifier cancels the same interference that occurs at each input.
But maybe you should make your previous circuit again but with neat wiring to avoid the interference picked up by the messy wiring.
oh.. great news...
its working. you where correct @BradtheRad & @Audioguru
the noise are from the source only the very 1st design worked when i powdered it up using 9V battery & 7805,
i am getting correct & 5v level output...
Thank you all.:thumbsup: