Stimulator/Isolator for Precise Current Delivery

Order code

Constant current stimulus isolator with integrated pulse generator

  • Up to 10 mA of constant current with built-in pulse generator
  • Unipolar stimulation
  • Built-in non-compliance alarm
  • Input is optically isolated
  • Manual, external sync, gating or standard
  • TTL triggering
  • DC test mode
  • Output polarity/“on/off” switch
  • Powered with six rechargeable lead acid batteries
  • >100V compliance


Part # Description Battery Type Includes Charger
A320RC A3A320R with A362 Battery Charger Rechargeable Battery Yes
SYS-A320R Isostim Stimulator/Isolator Rechargeable Battery No


  • Cost-effective for budgets which limit purchasing a separate stimulus signal generator
  • Built-in free running pulse generator can be externally gated for bursts
  • Test mode simplifies performance verification
  • Optical isolation enhances safety of the preparation and reduces noise susceptibility
  • Save on a rechargeable system when purchased as A320RC


  • General purpose brain and CNS electrophysiology
  • Neuro-electrophysiology teaching labs

Exceptional timing control

Pulse interval and width are set with single-turn continuously variable con­trols from 5 ms to 5.5 s in three ranges. Pulse width is continuously variable from 50 µs to 550 ms in four ranges.

Modes of operation

In FREE RUN, Isostim™ generates con­tin­u­ous square waves. In EXT GATE or EXT SYNC modes, externally applied pulses can generate trains or single events. Single pulses of finite duration can be produced using a push-button on the instrument’s front panel. EXT/DC mode converts Isostim™ to a passive stimulus isolator.

Dual tone audible alarm

A tone sounds when an open circuit is detected or when system compliance is reached. A second tone, which sounds when a signal is applied to the input, can only be heard if the batteries have sufficient charge to operate the isolator. A violation light advises when pulse width exceeds the interval.

Precise current delivery

Stimulus currents up to 10 mA can be set on the front panel with a control knob and a two-po­si­tion range switch. Output current is load-in­de­pen­dent.


Isostim™ model A320D is powered by readily ob­tain­able 9-volt alkaline batteries (in­clud­ed). Un­der average use these will last several months before re­place­ment is required. The re­charge­able A320R is supplied with a nickel metal hydride battery stack which provides 10-12 hours of operation before recharge is required. The A362 Battery Charger must be used with the A320R.

NOTE: Not intended for human use.


5 ms to 5.5 s continuously variable in three ranges (0.18 to 200 Hz)
Pulse width 50 μs to 550 ms continuously variable in four ranges
External sync

Accepts 1 μs minimum pulses
External gate Accepts 1 μs pulse to continuous
Ext. command voltage threshold 5 V at 3 mA min., 8.5 V max.

DC, pulse from internal timing or externally generated pulse
Current ranges 0-1 mA, 0-10 mA
Load voltage excursion (compliance) 100 V nom., 150 V max.
Output polarity Reversible, manual switch
Current rise time and delay 8 μs, typical (1 KΩ load)
Current fall time and delay 10 μs, typical (1 KΩ load)
Leakage resistance, output to ground 1012 Ω
Optocoupler 2500 V rated min. breakdown voltage
Dry Cell (Version D)

16 alkaline 7.2 V batteries included
Rechargeable (Version R) 16 rechargeable NiMH 9 V batteries included
DIMENSIONS 8.5 x 3.5 x 4.9 in. (22 x 9 x 12 cm)
SHIPPING WEIGHT 4 lb. (1.8 kg)

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