:: a small project for USB noise reduction

I am starting a small project to build USB dongles that reduce EMI/RFI noise.

But there isnt much prototype pictures to show. the circuitry is pretty much power in and power out thru high end filter components, and a very interesting differential USB line design to cater for "low density" fab FR-4 PCB (@ 1.25Ghz / 90ohms nom).

this pic is 1 of the earlier power line common mode choke experiments. it stands at roughly 67mH (11AWG magnet wire). It was accidentally broken. These ferrite toroids are very very very brittle. This was designed to low pass approximately 1kHz (for main ACs power). It was a very crude prototype.



and this is an earlier design of the USB noise filter. there were about 15 designs, including the few active USB 1.0 full 1kV isolation filters using ADUM4xxx series. This series of isolation products are quite common.

so I thought it be interesting try something simpler, and to bring this to public domain by offering a kickstart/indiego.

no active circuits, full passive components, simple design. wideband EMI/RFI filtering.example of use :
- USB SDR radios
- USB oscilloscopes (esp for measuring very small voltages)
- USB audio products

an additional 30dB of signal to noise in the incoming power line may not look like much, but for those who understood PWM PSU noise, they range in 10s of millivolts AC upwards. a 30dB reduction means making these go under 1millivolt (100s of uV or less). This website have very good PSU tests, but for the past 3 years, it seem Mr Torres is no longer there?
http://www.hardwaresecrets.com/silverstone-strider-plus-600-w-st60f-ps-power-supply-review/10/
He even posted scope views of the noise.

The noise is real, but this effect does not affect everyone drastically. Most consumers accept the usual pink/white noise. So this kickstart/indiego is for individuals looking for a "cleaner" USB power supply line and understands what the averaged reduction means.

general specifications of the design/construction
- max 2.5A current capacity (8A burst 10second)
- 30kHz to 1.2GHz range with 30dB attenuation
- beyond 5kHz to 2Ghz range with 10dB attenuation
- using genuine MURATA parts
- USB 2.0 signal path design considerations (1.25GHz)
- internal DC resistance 26~50milliohm (excluding contact variance of 10milliohm)
- net weight approximately 85grams (excluding heat shrink variance)
- crowdfunding cost per unit USD59.00
- expected time to start construction 30days
- expected time to complete 60days
- maximum pieces to be made = 50 (for first run)

Popular Posts