The IE-251A is a moderately priced intracellular electrometer complete with current passing capability and incorporating the same basic design as the more costly IE-210.

• Fixed gains of x1 and x10
• Capacity Compensation neutralizes input capacitance for up to 50 pF
• Junction potentials of up to ±200 mV are nulled with the DC Position control
• Electrode Test provides convenient electrode resistance check
• Push button operated Buzz produces oscillations at pipette tip to facilitate cell impalement
• Convenient Probe Test port permits fast check of amplifier performance

The IE-251 is a low cost version of our popular IE-210 intracellular amplifier. The important features required for low noise, drift free recording from glass microelectrodes have been retained in this lower cost model. The IE-251A is easy to use and is an excellent choice for the budget-conscious researcher or student teaching lab. It features a very small active headstage, essentially the same as used with the more costly IE-210. Epoxy-sealed construction affords maximum resistance to saline corrosion. Its small size and low mass permit easy mounting in a micropositioner. The electrode holder supplied connects directly to the probe input.

Current Injection

The injection circuitry of the IE-251A allows simultaneous stimulation and recording through microelectrode resistances up to 1000 MΩ in two ranges. Voltages at the Stimulus Input are converted to constant currents applied to the electrode. The steady state and transient components of the current injection artifact are nulled with the DC and transient balance controls. The corrected signal is viewed at the single-ended bridge output. Electrode resistance is read from the DC balance ten-turn dial.

Overdrive Indicators

Two visual indicators call attention to overload conditions:

• Input Overdrive is illuminated whenever the probe input voltage exceeds ±1 V, caused by either excessive current through the microelectrode or an open circuit (open or blocked electrode)
• Current Overdrive warns of excessive voltage (>50 V) applied to the Stimulus Input

The IE-251A is supplied with a probe. However, an electrode holder must be purchased separately based on your glass outer diameter. Also, specify line operating voltage if other than 100-130 VAC. Typical electrode holder options are listed below with pricing information.