Midgard™ Precision Current Source

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Product Code: Model51595
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• New screen: 2.5 times larger

• Touch screen programmability

• Universal power supply

• Internal memory

• Integral high-voltage labels

• Real-time feedback of current status

• Error warning for current interrupt

• Error warning for out-of-range


For Iontophoresis

The latest generation of the popular precision current source, designed at M.I.T. for the iontophoresis of neural transport tracers such as horseradish peroxidase (HRP) or tritiated amino acids into neural tissue, is now available from Stoelting. It may also be used to make small lesions, and in applications requiring precise current control through high impedance.

3000 Volt Compliance Voltage

The Midgard™ features a high compliance voltage (3000 V) for injections from very small, or partiallyclogged, pipette tips. The output current level can be regulated to +/- 0.5%, from 0.0 to 200 MegOhms.

Pulsed or Continuous Output

Pulsed output helps avoid clogging or polarization of the tip of the pipette. The researcher may select pulsed or continuous current with a switch. The pulsed on/off times can be varied from 0.5 to 24 seconds.

External Control

Many researchers have requested external timing control for lab automation applications. The Midgard™ can be gated through a headphone jack, on the rear panel, by any laboratory logic pulse generator. The output current is continuous whenever the gating jack is logic high, off when it is logic low.

A touchpad switch allows reversing polarity. This is useful when using a retaining current to hold the pipette contents in the pipette during entry into the brain.


HRP in tris buffer, pH 8.6; rat; lateral habenula. 2μA pulsed current, 15 minutes, 12 μ pipette.


Tritiated prolineleucine. VM nucleus, thalamus. 1μA pulsed current, 10 minutes, 20 μ pipette.

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50880   Silver Wire, .005in, 10ft., Bare


Output current:         0 to 25 µA, set by touch pads

Compliance voltage:           3000 V

Load current accuracy:       0.5% at 0.0-200 MegOhms

Load current reproducibility:         0.25%

Polarity:                              positive or negative, user selected

Display resolution:                 0.01 µA

Output connectors:          Two integral H.V. Cables

Pulsed Mode Operation

Pulse duration:           0.5 to 24 seconds, variable

Duty cycle:                     preset to 7 sec. on / 7 sec. off

Timing error:                   +/- 5%

Load current fall time:       0.1 sec.

Load current rise time:            Dependent on load resistance.

For 7.0 µA through 200 MegOhms, rise time to 99% of set value is 1 sec; over-shoot less than 5%