LED synchronized ringing or noise on IZ2

Tech Note: TN0927
Product: IZ2
Version: All
Date Added: 2013-09-05

Issue

When using the IZ2 stimulator in an electrically shielded environment (such as a Faraday cage) you might see LED synchronized ringing and/or a thicker noise floor when operating in Voltage mode. These symptoms are caused by radio frequency interference that is concentrated by the shielding, coupled with the equipment chassis and ultimately runs down the lines causing the interference to be picked up in recordings.

Solution

Adding ferrite beads to the LZ48 battery cable and LZ48 ground cable chokes the RF signal out of the lines, substantially suppressing the amplitude of the LED- synchronized pulse and lessening the RMS of the noise floor. Place the RF chokes towards the LZ48 side of the cables. Also, insulating the bottom of the LZ48 from any metal surface is highly recommended. Contact TDT for a cable kit.