Positive and negative red LED's function as a range and linearity monitor to keep you informed of usable voltage range of the probe. The DC level seen at the output is constantly monitored at the X1 output and illuminates the LED's if the +/- 14V input range is exceeded. No need to perform Ohm's law calculations to operate the Cell Explorer. These conditions represent non-linear operation of the amplifier and are usually due to either tip blockage or excessively high stimulus current through very large recording electrodes, causing the input amplifiers to saturate. Immediate knowledge of an over-range DC voltage can be very helpful in troubleshooting set-up problems.

Stimulus Current:

Internally set stimulus level may be triggered or "gated" by an external stimulator or pulse generator without the need of a separate stimulus isolator. Dual current range stimulus of 1,000 and 100nA, and with optional probe of up to 10 microamp range. Three switches and a 10-turn digital dial enable the 8700 user to program either continuous hyperpolarize or depolarize current in two ranges up to 1000nA with gated current pulses at either polarity from 0 to 1000nA without the need of a separate stimulus isolator. The gated or pulsed current feature is completely unique to the Dagan 8700 Cell Explorer. A simple digital signal can gate or control precise analog stimulus currents selected by the controls on the Cell Explorer front panel. This feature can greatly simplify your other equipment needs by enabling you to use inexpensive pulse generators for stimulators.

Bridge Balance:

The 8700 Cell Explorer has twice the range of other bridge balances and is usable with up to a 1000 Megohm microelectrode. A digital dial provides you with ten times the resolution of rotary 10-turn dials.

Filters:

In addition to an automatic 45db deep (200-to-1 attenuation) 60 cycle or 50 cycle line notch filter, the 8700 Cell Explorer also contains an additional two high frequency filters normally not found in any intracellular preamplifier. The 300Hz filter is useful for very low frequency work and the 100kHz filter enables controlled high speed operation.

Input/Output Connections:

All BNC connections to and from the Cell Explorer are made in one area on the bottom left-hand side of the front panel. This eliminates the criss-cross network of cables found when input and output connectors are located randomly on the front panel. In addition, this area contains the GATE INPUT BNC. A 5V logic pulse into the GATEconnector (with the HOLDING switch in the GATED position) allows external control of front panel programmed current used for stimulation.

•  8700N Cell Explorer Advanced: Comes standard with Options E, X, B, F, V and G (listed below) and 8720 Relay Probe.
• 8720 Breakaway Relay Probe: (MUST be ordered at time mainframe is ordered.) The 8720 enables the microelectrode to be switched via a reed relay in the probe, to a BNC connector for either connection to a high voltage for staining, or to a second amplifier. The relay can be manually controlled from the 8700 NORM/STAIN Switch or from an externally supplied logic voltage. Specify "probe mounted BNC"(best for second amplifier applications, ie., fast and low noise) or "mainframe mounted BNC"(best for staining applications). Mainframe BNC will be supplied if not sepecified.
• 8730 Low Current Small Box Probe: Divides current range by 10; useful for microelectrode resistances of greater than 100 Megohms.
• Option 'S' - Isolated Power Supply: AC supply located 10 feet from the 8700 mainframe to eliminate coupling from the AC power cord
• Option 'E' - Six Input/Output Functions: BNC connectors repeated on the rear panel.
• Option 'X' - X100 Output
• .Option 'B' - Buzz Switch: Facilitates cell impalement using oscillation.
• Option 'F' - Input Bias Current Adjust: Front panel mounted grid current adjustment.
• Option 'V' - DC Offset Voltage Control: A second uncalibrated bucking voltage.
• Option 'G' - Gate Option: Five volt logic level gates externally supplied stimulus signal.

Headstage Probes

Accessories BNC sized Pipette Holders (Also see Pipette Holders & Parts section)