Part number US1440, these sensors are not dual use, which means the transmitter and receiver is not exchangeable. They also look identical from the outside, so if you build my arduino ultrasound ranger with these (as I did) and find you can't see echoes, try swapping your transmitter and receiver around! It cost me no small amount of headach this morning.
Cheers,
Steve
Code to drive it is avaliable under GPL.
An updated version of the schematic as a .sch file is available also.
Cheers,
Steve
Goes like this:
I have a right to decide what happens to my children!
To that I say, we have the right to not be a victim of your stupidity. Further, laws represent social contracts that all members of society enter into for everyone's benefit. Getting vaccinated is one such contract which serves to prevent epidemics of infectious diseases.
If you really don't want to vaccinate your child, then please ensure your child never comes into physical contact with the rest of society for our sake. I would not welcome them without vaccinations.
Cheers,
Steve
What is the period if you want to generate a 40KHz signal? It certainly isn't 250E-6 seconds. The same calculator returns 2500E-3 for 1/4 which is 2.5, not 0.25.
The calculator is PEMDAS.
Cheers,
Steve