Electronic – Sharp Infrared sensor-Filtering supply ripple


I am using Pololu's sharp infrared sensor board part# GP2Y0A60SZLF and I am trying to minimize the noise caused by the sensor on the voltage supply as much as possible.

I have made a filter and voltage regulator circuit as shown below,
The IR sensor and the filter PCB are directly connected together. The output is carried out via a wire 7" long from the filter circuit as shown to a main PCB that has another RC filter (R2,C10)
filter schematic
Here is the scope shot at the 6-12v supply terminal. The spikes below are 1khz, 46mv p-p.
Scope Probe VDD

What do you suggest to clean the supply line below?

I am also including the waveform on the sensor output.

Sensor Output

Best Answer

This sensor draws like 300mA in bursts, likely you can see that on the power. I have had a similar problem with driving servos, which made huge spikes on the power line when powering from a lab psu.

I suggest to:

  • power this all with a battery with small internal resistance, i.e. alkaline AA cells, or LiPo
  • increase c3 to at least 470uF or 1000uF
  • (might try LC filter on the power lines)

The output signal is not bad with 30mV of noise. Your idea of the RC filters look correct. I'd give also a try with bigger C and smaller R, like R of not more than 1k, and C of some microfarads.

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