I am trying to convert a pwm signal from a JR radio control receiver to plus/minus 10 volt to drive a motion controller. the input to the controller has 120K ohms impedance. 12 bit sampling frequency 2 kHz

My curent setup is wire from the receiver channel to a R-C low pass filter, and feeding that into a NE5534AP op amp.
the R-C filter seems to look ok on the scope although the voltage drops from about 3.5 to .5 volts.

I have been days trying to solve this problem. Can someone give me some guidance please. I have a very basic knowledge of electronics.

Thanks

 

This may be a start.
Max.

 

Thanks for the reply.
Is this for generating a PWM, as I have already got the PWM coming from the receiver.

Paul

 

PWM to analogue conversion.
Max.

 

I just looked at the data sheet, it looks really complicated, My goal is to drive 10 axis bruges servo motors wirelessly I have 2 axis working so far but hard wired. So decided to look into wireless control.
I'll do some reading on the chip to see if I can get my head around it.
Paul

 

There was no chip in the PDF, only a way on page two to calculate the lowpass filter. What is your PWM clock frequency, and can you post your schematic?

ak

 

On my calculation it is either 22 or 44 kHz

 

Sorry forgot to put the schematic

 

Can anyone help out here?
Paul

 

Not sure if this will help, but this is what I'd do:

Feed the PWM (I assume 0-5V) to an op amp configured as a level detector. Configure the level to be detected as 2.5 V. This should give you a +/- 10 V output if you adjust the supply voltages to the op amp.

 

Thank you. I think there will be a waveform coming out of the op amp do you use a rc low pass filter?

Do you have a schematic you could share?

Paul