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RA4PA Tech Notes

Running a Medusa PreAmp off an external battery

TN0256

Product: RA4PA, RA16PA, RA16SD
Version: All
Date Added: 2007-07-12

Issue

Customers looking for extra battery life for their Medusa PreAmp can purchase the PZ-BAT external battery pack from TDT.

Alternatively, off the shelf 6V batteries, such as a motorcycle battery or a battery for use with emergency lighting, can be adapted for this purpose. A battery/charger that has worked can be found here:

https://www.batteriesplus.com/replacement/battery/power-sonic/ps6120ts/slaa6=14t2"

and

http://www.batterystuff.com/battery-chargers/6-volt/SON604CC.html

This battery has a capacity of 12 Amp-hr, which should power an RA16PA for about160 hours.

This type of battery can be connected to the voltage inputs of the PreAmp using a Digi-Key connector (part number SC1051-ND). The connector will have to be wired to utilize the desired battery.

Caution

The SC1051-ND connector is center negative. Inverting the connection will damage the PreAmp.

Using RZ processors, BioAmp input appears clipped or larger than expected

TN0217

Product: RZ2, RZ5, RA16PA, RA4PA
Version: All
Date Added: 2006-09-19

Issue

When using the RZ2 or RZ5 processor BioAmp input from the Legacy Medusa PreAmps will appear too large or clipped unless a scale factor is applied.

Workaround

The Legacy Amp, RA16PA/RA4PA inputs must be scaled by a factor of .000833 The RZ Input Macro applies the appropriate scale factors automatically. However, if the macro is not used in the circuit, the user must use Scale Add or MCScale to ensure the scale factor is applied.

Solution

Use the RZ2_Input_MC macro for RZ2 or RZ5_AmpIn and RZ5_AmpIn_MC macros for the RZ5.

Some RA16PA and RA4PA generate a 3 kHz noise that masks neural activity

TN0067

Product: RA16PA, RA4PA
Version: Serial numbers < 3000
Date Added: 2002-12-17

Issue

Some RA16PA and RA4PA with serial numbers < 3000, generate a 3 kHz noise that masks neural activity.

Solution

The voltage regulation on the preamplifiers has been modified to provide better control of voltage variation. The preamplifier has also been modified so that low battery voltage is indicated earlier. This 3 kHz noise artifact is not generated on all headstages with all electrodes. We recommend updating to the new preamplifiers only if your system generates this noise.