Independent Power Supplies

Steve2010

Hi,

I am using the Parallax Professional Development Board with a BS2.

My application requires ultrasonic sensors that require a supply voltage of 15-30VDC with maximum current consumption of 35ma that produce an output signal of 0-10V / 10-0V.

I am very new to this field and would like to have a completely independent non-battery power supply for the ultrasonic sensors to separate them from the Development Board circuitry (which uses a Parallax 12V 1A wall power adapter). Would I want to obtain perhaps a 15V wall pluggable switching power adapter and if so should I incorporate some type of circuitry to ensure the proper output voltage and current? What current rating should the plug-gable power supply have? Is there a better method than this?

Also, how would I interface the 10V output signals into a ADC chip that resides on the BS2 development board?

In advance, many thanks!

Mike Green

It's hard to advise you without adequate information about your sensors. I assume they would be fine with any supply voltage in the stated range (15-30VDC). I would recommend that you don't stick with either end of the range because, if you pick 15VDC for your power supply, it will be a few volts low and won't work properly. Pick something in the range of 20-25V. As far as current rating is concerned, anything greater than the maximum current consumption of the sensor should do. Anything from 50mA to maybe 100mA should be fine. How regulated this needs to be depends on the sensor. You could easily use an LM317 to provide a 16-18V regulated output with a 24VDC unregulated input.

A simple voltage divider could take a 0-10V signal and reduce it to a 0-5V range for use with an ADC chip.