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can any one help for ultrasonic

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scorpionss22

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hi all the schematics below is from epemagazine
this circuit work at 40khz ultrasonic transmitter and receiver
but i only had 32 khz
so how can i modify this circuit to work with 32 khz
thanks for cooperation
 

It is the code that resides in the PIC which is responsible for frequency.
So the only way to change the frequency from 40kHz o 32kHz is to modify the code.
Do you have it or do you have access to it?

Added after 9 minutes:

One other thing that you can try is to change 4MHz crystal quartz to 3.2768MHz (that is the closest available, but I think close enough).
It is just an idea ..
 

the project divide into 2 stage
1- transmittion :
this part i can do it with 32khz
i know how can i programm the pic

2- receiption:
the receiption depend on the amplification of the echo here is the
problem
i think this circuit (i mean the amplification stage ) is for 40khz
i mean the component of (R , C) is calculatred for 40 khz
i need to know what is the component value for 32khz

thanks
 

No, these components are not calculated for 40kHz.
You can easily use the same values for 32kHz.
First amplifier gives you gain1 = 100 (1M/10k), second gain2=47(470k/10k)
Impedance of 22nF cap at 32kHz is about 250Ω so does not play any major role ..
 

IanP said:
It is the code that resides in the PIC which is responsible for frequency.
So the only way to change the frequency from 40kHz o 32kHz is to modify the code.
Do you have it or do you have access to it?

Added after 9 minutes:

One other thing that you can try is to change 4MHz crystal quartz to 3.2768MHz (that is the closest available, but I think close enough).
It is just an idea ..
Click to expand...

IanP is correct, it is done in code.10 pulses are transmitted and the time taken to transmit them is equivalent to a frequency of 40Khz.
You will have to do the adjustments in the TXIT and BEAMIT routines for a frequency of 32Khz as well as in the RECIEVE routine which has a 2 byte timing counter.
I suggest you go to the epe site and download the source AND documentation, which explains the method of operation.

Hope this helps.
 

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