how did you conclude it is +/- 9V swing but not +/- 10V or +/-5V swing ?

hi,
I have lost count on the number of projects I have used the MAX, +/-9V is typical.
E

 

Why am I under the impression that the circuit posted by the OP is intended to convert a PWM input signal into a linear output voltage?

Hi,
To convert PWM input signal to linear output voltage requries low pass filter. But here High pass filter is used.

Here Tout to Transmitting sensor do send continuous Signal.

 

Hi,
To convert PWM input signal to linear output voltage requries low pass filter. But here High pass filter is used.

Here Tout to Transmitting sensor do send continuous Signal.

How familiar are you with LTSpice? Maybe it would be best if you saw what the circuit's output would look like using a simulator.

 

Why am I under the impression that the circuit posted by the OP is intended to convert a PWM input signal into a linear output voltage?

Probably because the OP did not adequately understand the actual and intended functionality of the MAX232 device. Since it is rather unique in using a charge pump to supply the higher voltages needed for traditional RS232 applications, that is why a search engine spotted it. And it would appear that the wickapedia explanation is a bit incomplete, as well.

 

Your circuit behaves in a very strange way ... what is it exactly that you're trying to accomplish?

 

hi,
As I understand the TS's project.
The input to MAX T1 pin will a short burst of 40kHz square wave TTL pulses. the MAX will convert these pulses into 40kHz at +/-9Vpk pulses.
These +/-9v pulse will drive a 40kHz ultrasonic transducer.
E

 

hi,
As I understand the TS's project.
The input to MAX T1 pin will a short burst of 40kHz square wave TTL pulses. the MAX will convert these pulses into 40kHz at +/-9Vpk pulses.
These +/-9v pulse will drive a 40kHz ultrasonic transducer.
E

So the input frequency will be fixed?

 

Also, the MAX232E, for instance, has a maximum output current of 10mA. That amounts to a maximum power of 80mW ... would that be enough to drive an ultrasonic transducer?

 

hi,
As I understand the TS's project.
The input to MAX T1 pin will a short burst of 40kHz square wave TTL pulses. the MAX will convert these pulses into 40kHz at +/-9Vpk pulses.
These +/-9v pulse will drive a 40kHz ultrasonic transducer.
E

Hi,

Input pin to MAX T1 is from Atmel microcontroller. So it will send a 40Khz squarewave TTL signal to MAX232?

I still could not figure out why a high pass filter followed by a resistor(330 ohms) is used from the T1out pin for a Transmitter. Is it remove the low-level noise generated from MAX. and how do you calculate the values of it?

Thanks in advance.

 

Hi,

Input pin to MAX T1 is from Atmel microcontroller. So it will send a 40Khz squarewave TTL signal to MAX232?

I still could not figure out why a high pass filter followed by a resistor(330 ohms) is used from the T1out pin for a Transmitter. Is it remove the low-level noise generated from MAX. and how do you calculate the values of it?

Thanks in advance.

I'm quite familiar with atmel's MCU's. What specific chip are you using?

Perhaps the filter is there to remove the DC component of the signal, in case it gets stuck on high.

 

hi 789,
I will run a LTSpice simulation of the project, post tomorrow.
My colleague @cmartinez has done an LTS sim , perhaps he will create a sim for the Filter network.?

E

BTW: Post your circuit of the receiver amplifier.

 

I'm quite familiar with atmel's MCU's. What specific chip are you using?

Perhaps the filter is there to remove the DC component of the signal, in case it gets stuck on high.

Hi Martin,

I am using AT90CAN64.

Thanks for the help.

 

hi 789,
This is what LTSpice shows with a 40kHz transducer.
E

 

hi 789,
This is what LTSpice shows with a 40kHz transducer.
E
View attachment 188168

Hi Eric, Thanks for the simulation. It looks like there is no improvement with the use of high pass filter and resistor, further it increased the ringing time which is bad for target detection.

what's your analysis on this.

Thanks in advance.

 

hi 789,
Its possible the designer had a push push drive design.

If you use T1 and T2 and can get the phasing correct, you will get this higher drive.
Note the bottom plot window.

E


BTW: Ringing is a fact of life with this type of circuit

 

hi 789,
Its possible the designer had a push push drive design.

If you use T1 and T2 and can get the phasing correct, you will get this higher drive.
Note the bottom plot window.

E


BTW: Ringing is a fact of life with this type of circuit

View attachment 188169

Nice! ... can you post the asc file? I'd like to see how much power this circuit is drawing.

Hola, Presto #35