STM CircleOS forum / high power noise

Saulis · 2009-04-22 09:12:02

I'm currentlly tuning my extension board circuit. Heart rate receiver is just overloaded by... dc/dc converters noises. Adding some more capacitance, noise is lowering. Besides, caps are too small I think. after power up, while message is playing, I can see almost sprectrum in receivers output before detector... thus its is difficult to operate in these situation..

Saulis · 2009-04-22 09:37:23

suggestions for next implementations. Ground connections should be 2-3 times wider(spoke width). For all electrolytic caps (decoupling noise) trace width should be reviewed. Especially around power supplies. Because there will be no good implementations of external sensitive hardware(EKG amp, even EEG amp). If RFID would be affected I dont know, but in this case you can try to read some times..

Francis · 2009-04-22 12:47:08

The quality of the power has been improved for the next implementation. At the moment, I suggest that you add filtering on your extension board.

Saulis · 2009-04-22 13:34:38

Polar heart rate receiver(or DIY receiver) uses inductance as electromagnetic antenna, show noisy power supply is not only on electric plane, but also in magnetic field near device. Added bigger capacitance on VCC2v8(replaced C20 to 100u), also relpaced C54 to the 100uF. Soldered pad grounds to vias with some wire. After this, distance increased 10cm(~30cm now, thus powered externaly reaches ~70cm(it mainly depends on indutance Q at 5kHz). Thus original Poral receiver is saturated(then mounted in the same place as mine circuit)...

Last edited by Saulis (2009-04-22 13:35:18)

# 1 2009-04-22 09:12:02 high power noise

high power noise

# 2 2009-04-22 09:37:23 high power noise

Re: high power noise

# 3 2009-04-22 12:47:08 high power noise

Re: high power noise

# 4 2009-04-22 13:34:38 high power noise

Re: high power noise

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