Micro Electrode D.C. Amplifier

Engineering Psychology

Accession Number: 2014.ep.18.1-2

Instrument Name: Micro Electrode D.C. Amplifier

Description:

Two D.C. amplifiers, identical models, tagged as 2014.ep.18.1,2. The items have painted steel cases, with adjustment knobs and terminals on the front, right-hand, and left-hand sides. On the left-hand side, there are two coaxial terminals, eight terminals with coloured plastic covers, a six-pin connection point, and two small output/input terminals for battery calibration. On the front face, there are eight adjustment knobs, labeled the following: COMPENSATION (CAP and AMPLITUDE), INPUT SELECTION, Rk MEG, A.C. OUT T.C., RISE TIME, AMPLIFICATION, and CALIBRATION (MV). The knobs appear to be aluminum. One of the aluminum knobs has a gold anodized coating, and one is painted black. There are five switches, labeled BAT.TEST (-/+), BATTERY (ON, OFF/CHARGE), CRO ADJ./USE, INPUT OFFSET POLARITY (-/0/+), and CALIBRATION (CAL.-/CAL.+). There is also a dial marked counterclockwise from 0-90, in steps of ten, and an analog needle readout ranging +2.5 to -2.5. On the right hand side, there is a charger input, terminals for D.C. and A.C. output, a ground connection, and a terminal marked EXT. CAL. IN. On the rear face, there are two plastic support brackets, centered and arranged vertically. There is also a silver coloured sticker attached to the rear face in the bottom left corner.

The items have two-part steel cases, with one part painted light blue and the other painted to resemble wood veneer. The front and side faces are formed by the first part, and the rear, top, and bottom faces by the second part.

2014.ep.18.1) The lower support bracket on this component is cracked. There is a paper label and piece of tap affixed to the top face. There is tape residue on the bottom face. A red plastic label is affixed to the front face.

2014.ep.18.2) The casing has been separated and repaired; the two parts of the case are not aligned. There is a torn paper label on the top face, as well as five tape pieces of varying size. There is a piece of tape affixed to the rear face. A red plastic label is affixed to the front face.

These items are accompanied by original instruction manual and catalogue.

Primary Materials: Steel, Aluminum, Plastic

Markings:

There are a number of markings around the knobs, switches, dial, readout, and terminals denoting their function and values of each switch or knob position. All markings are in black paint.

On both components, the manufacturer’s mark “GRASS”, model number “P16″, and device name “MICRO ELECTRODE D.C. AMPLIFIER” is marked in black paint on the front face. On the right hand side, the components are marked “GRASS INSTRUMENT CO., QUINCY, MASS. U.S.A.” in black paint, The manufacturer’s logo is also marked on this face in black paint.

2014.ep.18.1: The paper label on the top face is marked “Combination Skin Resistance (AC) P[Illeg.]” in blue ink. The piece of tape is marked “”New Battery Pack 1/79″ in blue ink. The silver label is marked “GRASS INSTRUMENT CO. QUINCY, MA. USA Mod. P16C Date 3-77″ The markings on the label are mostly in black ink; the markings “P16C” and “3-77″ are impressed in the sticker without ink. The red plastic label affixed to the front face is marked “II”. There are markings on the front face in black ink, reading “MODEL P16C” and “Serial 781Q1A”.

2014.ep.18.2: The paper label on the top face is marked in pencil; the markings are illegible. One of the pieces of tape on the top face is marked “Reconstructed Battery Pack 1/79″ in blue ink. The piece of tape on the rear face is marked “NB. Both Amps have charging circuit modified 56060 Resistor in series – ∴ 22ma charger ⇒ 12 ma trickle charge”. The silver label is marked “GRASS INSTRUMENT CO. QUINCY, MA. USA Mod. P16C Date 3-77″ The markings on the label are mostly in black ink; the markings “P16C” and “3-77″ are impressed in the sticker without ink. The red plastic label affixed to the front face is marked “I”. There are markings on the front face in black ink, reading “MODEL P16C” and “Serial 781Q2A”.

Dimensions (cm):

Length = 20.2 cm, Width = 13 cm, Height = 13 cm

Function:

Used for EEG measurements, provided current for intracellular stimulation of scalp,used with probe (not included).

Condition:

2014.ep.18.1: Good to moderate: all components of the device are intact and relatively unworn, aside from the bottom support bracket.

2014.ep.18.2: Moderate: all components of the device are intact and relatively unworn. The casing has been repaired and is off-centre.

Manufacturer:

Green Instrument Co., Quincy, MA., U.S.A

Date of Manufacture: February 1977

Provenance:

Acquired from the Department of Engineering Psychology, University of Toronto. Acquired from the laboratory of Paul Milgram.

Additional Information and References:

Peltoranta, Mauri, Jaakko Malmivuo, Kimmo Nieminen, and Simo Oja. “Microelectrode Amplifier for Intracellular Stimulation and Recording.” Medical & Biological Engineering & Computing 21.6 (1983): 731-38. Web.

Virtanen, J., J. Ruohonen, R. Näätänen, and R. J. Ilmoniemi. “Instrumentation for the Measurement of Electric Brain Responses to Transcranial Magnetic Stimulation.” Medical & Biological Engineering & Computing 37.3 (1999): 322-26. Web.

Donated to UTSIC: Yes