Duo 773 Electrometer
2-Channel intracellular amplifier for dual and differential studies
- Two channels for differential or intracellular ISE
- Integrated DC current generator with external control input
- Integrated low pass filter
- Bridge balance circuit to null out electrode voltage drop
- Tickle circuit
- Integrated test ports for each channel
- Dual capacitance compensations and output offset controls
- Comes complete with 2 probe headstages, normally one high impedance and one low impedance
- Dual channel, single ended recording
- Differential recording
- Bridge circuit nulls electrode voltage drop
- Assign low pass filter to either channel
- Very high impedance channel can be used with intracellular ISE
- Intracellular electrophysiology using sharp micropipettes
- Brain slice intracellular recording
- In vivo intracellular recording from brain and spinal cord
For intracellular dual or differential studies, the Duo773 has separate negative capacity controls and built-in active filtering that allows the precise balancing of time constants for artifact-free differential measurement. Comes complete with two probe headstages, 1015Ω and 1011Ω probes to monitor signals from ion-specific micro-electrodes as well as KCl-filled electrodes.
Headstage for precise positioning
Two gold-plated, epoxy sealed miniature active probes can be positioned directly to the measurement site. Microelectrode holders containing an Ag/AgCl electrochemical half-cells plug directly into the probes. Stray capacitance can be reduced by placing the included driven guard shield over the microelectrode holder at the end of the probe.
Channel A can compensate up to 10 pF of electrode shunt capacity and Channel B can compensate up to 50 pF.
Tickler circuit for penetration
A Tickler Circuit assists in cell penetration. The frequency and amplitude of the oscillations may be varied for differences in membrane thickness or cell size. The duration of tickle can be controlled either by using the momentary switch, a foot switch, or by applying a signal to the remote tickler input.
Low pass settings on a -40 dB/decade active filter vary the cutoff from 1 to 30 kHz. Either probe or bridge outputs may be selected for filtering.
Channel B can eject current through the microelectrode by applying a command signal to the stimulus input connector. The resulting output from the probe will be a constant current replica of the input signal. Two ranges of current delivery are provided: 50 nA and 500 nA or by an external source. This source can be useful for delivering hyperpolarizing currents to stabilize the cell membrane potential and as a holding current for microiontophoresis.
Subtracts the excess electrode voltage associated with delivering current through the recording micropipette. Electrode resistances up to 1000 MΩ can be balanced in two ranges. The balanced signal is available from x10 or x50 front panel output connectors.
The Duo773 has an output for each probe independent of gain filtering or balancing. In addition the Duo773 has a 10x and a 50x output for easy integration to most data acquisition programs.
Optional holders for intracellular amplifiers
Other microelectrode holders
|HEADSTAGE (PROBE)||712P (red, port B)||715P (blue, port A)|
|ACTIVE PROBE INPUT IMPEDANCE||>1011 Ω||1015 Ω|
|OUTPUT RESISTANCE||100 Ω||100 Ω|
|OUTPUT VOLTAGE RANGE||±10 V||±10 V|
|MAXIMUM INPUT VOLTAGE||±15 V||±15 V|
|PROBE LEAKAGE CURRENT||5 X 10-12 A||10-14 A|
|DC POSITION ADJUST RANGE||± 300 mV||± 300 mV|
|ELECTRODE RESISTANCE TEST CURRENT||1 nA||1 pA, 1 nA selectable|
|INPUT CAPACITY COMPENSATION||+10 to -50 pF||0 to -10 pF|
Input shorted 712P
20 MΩ carbon resistor
<50 µV p-p 10 kHz bandwidth
<200 µV p-p 10 kHz bandwidth
<50 µV p-p 10 kHz bandwidth
<200 µV p-p 10 kHz bandwidth
10-90% direct input small signal
10-90% through 20 MΩ (-C "on")
1 µs, typical
25 µs, typical
|CURRENT INJECTION (712P only)**
Internal DC Current
Externally commanded Current 712P (red, port B)
External current command factor
Bridge amplifier gain
± 50 nA low range, ± 500 nA high range
± 500 nA low range, ±5 µA high range
20 mV/nA low range, 2 mV/nA high range
100mV/nA low range, 10mV/nA high range
3V low range, 10V high range
0-100 MΩ, 0-1000 MΩ
x 10, x 50
|LOW PASS FILTER||40 dB/decade, continuously variable 1-30 kHz|
Accuracy and resolution
200 mV, 2000 mV, 20 V, 200 nA, 2000 nA
17 x 5.25 x 10 in. (43 x 13 x 25 cm)
Diameter: 12 mm Length: 34mm
|POWER||95-135 V or 220-240 V, 50/60 Hz|
|SHIPPING WEIGHT||15 lb. (7 kg)|
* Although injected currents are “constant,” the maximum current in a given situation will always be limited by the system compliance of 10 V.
**The 712P headstage may be used on either A or B channels, however Current Injection specifications do not apply when used on channel A. The 715P headstage may not be used on the B channel.
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