0
\$\begingroup\$

I want to generate a pulse that have frequency 40khz and amplitude 20VPP to MA40s4s ultrasonic sensor operate. I use raspberry to generate pulse 40khz-5Vpp then using a IC CD4049BE to boost it into 20vpp as in the below figure. I have encountered the problems is that when i not insert sensor into circuit is waveform is very good but when i insert sensor, waveform is noised as in figure.Please give me how to resolve this problem. enter image description here enter image description here

\$\endgroup\$
  • \$\begingroup\$ Your 'scope photo shows only one side of the driver (either TP3 or TP4). The other side should appear similar, with 180 degree phase inversion. If so, I see no problem. You might want to increase C8 (more than 0.1uf) - it should be placed close to U3 power pins. \$\endgroup\$ – glen_geek Nov 10 '16 at 16:39
1
\$\begingroup\$

Capacitance of MA40S4S (about 2.55 nF) affects output of the power stage.

Consider using an IC with higher output current.

Or you can try a burst generator (mosfet + inductor) driven by the PWN signal. Example you can find on page 9 of AN4841: 12ZVL LIN Enabled Ultrasonic Distance Measurement.

\$\endgroup\$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.