A SIMPLE METHOD FOR MAGNETIC TAPE RECORDING OF BIOELECTRIC POTENTIALS,
Abstract
A system was built which includes a pre-amplification by means of one channel of a Grass IIID Electroencephalograph, a modulator with a 1N34 germanium diode biased (in parallel) with the +3 terminal available at the control panel of the IIID, a recorder (Ampex model 601, 7 1/2 in/sec, full-track), a demodulator of the peak-detection type using a series diode 1N34 and an RC circuit with a time-constant of about 10 msec. The carrier generator was a Grass S4 Stimulator which has an output impedance of 250 ohms and supplies a rectangular wave of a frequency of 2 kc/sec and a duration of 0.25 msec, with an amplitude of about 1V. In spite of a marked 'valley' in the amplitudefrequency curve at about 35 c/sec, it was not necessary to install a high pass filter between the modulator and the recorder. However, to obtain the frequency characteristic required by the International Federation of EEG Societies, it would be necessary to put (in series) a condenser of about 500 pF between the modulator and the recorder. It was also found that the system works without the positive 'clamp', owing, perhaps, to a high frequency deformation of the carrier square wave as well as to the fact that modulation was not very pronounced. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Nov 15, 1960
- Accession Number
- AD0612233
Entities
People
- E. Garcia-austt
- P. Handler
Organizations
- University of the Republic