how to count number of rise and fall in voltage level

A

anamikatripathi

New Member

• Feb 23, 2011

• #1

electronic stethoscope. need little hepl

i am designing a stethoscope based on measuring blood density at particular part of body as the density rises voltage level is 10v as density falls voltage falls to 6v i want to count the total number of rise and fall. if some1 can help me out in it its quite urgent i will be greatfull to you

 

Last edited: Feb 23, 2011

Grossel

Well-Known Member

• Feb 23, 2011

• #2

You can connect it to a derivator and then to a schmitt trigger where zero voltage is between the lower and upper trigger level. It takes two opamps.

After that you can use two monostable latches, one that activate at rising edge, and the other activates at falling edge. Each monostable latch outputs can connect to it's respective counter.

 

Last edited: Feb 23, 2011

A

anamikatripathi

New Member

• Feb 23, 2011

• #3

thanks but i am just a starter and i think using schmitt trigger will make circuit complicated can u send me link so that i can check and is there anything available in form of chip. or can we use threshold detector

 

A

anamikatripathi

New Member

• Feb 23, 2011

• #4

thanks it will work and i m great ful to u

 

Grossel

Well-Known Member

• Feb 23, 2011

• #5

Sounds like you want somebody to design this for you. A schitt-trigger isn't a complicated thing.

Read about:
Inverting differentiator
Schmitt trigger
**broken link removed** Look at the middle of the web page. It's a really simple circuit.

 

A

anamikatripathi

New Member

• Feb 27, 2011

• #6

i have done it and thought about using timer 555 and counter of pic16fxx micro controller will it work

 

blueroomelectronics

Well-Known Member

• Feb 27, 2011

• #7

Don't need a 555 if you've got a PIC.