DS2A Isolated Voltage Stimulator

DS2A Isolated Voltage Stimulator

£990.00 exc. VAT

Manufacturer's Net List Price

FEATURES

  • Low noise battery power supply with up to 99V output
  • Internal (20µs to 2s) or external TTL “gated” control of pulse duration
  • Two voltage ranges (0-9V and 0-99V) allow precise reproducible control of stimulus output
  • Polarity reversal switch
  • Battery test sockets
SKU: DS2A-MK.II Category:

Description

DESCRIPTION

The DS2A Isolated Constant Voltage Stimulator is a low noise solution for electrical stimulation of in vivo and in vitro preparations, in order to excite neurons, nerves or muscle fibres. Battery powered and isolated from its trigger source and ground, the DS2A is designed to deliver precisely adjustable voltage pulses, without introducing noise into electrophysiological recordings. The DS2A will output monophasic voltage pulses of up to 100V, which are widely adjustable in pulse duration and amplitude.

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DS2A Constant Voltage
Product Information

Application Note
Using two DS2A Isolated Constant Voltage Stimulators in series allows stimulation through the same electrodes with different pulse types.

Application Note
Using a DG2A Train/Delay Generator and two DS2A Isolated Constant Voltage Stimulators to produce a repetitive biphasic constant voltage stimulus.

DS2A Isolated Stimulator
Operator’s Manual

References
Publications which cite use of the Digitimer DS2A can be found on Google Scholar.

DOWNLOAD BROCHURE

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ACCESSORIES

Supplied

  • Operator’s Manual
  • One set of batteries (fitted)
  • One Pair of output plugs for user assembly (NL985P)

Recommended

FAQs

I want to stimulate with a longer pulse duration than 2 seconds, in order to lesion some tissue, is it possible to do this?
Yes, there are two simple methods. (i) The DS3 has the ability to be gated by an external pulse i.e. when external control of pulse duration is selected the output stimulus timing will be controlled by the trigger-in stimulus pulse. It should be noted that (with a 5V input pulse) there is only a very short delay of <2µs for the turn-on and <6µs for the turn-off. When a typical TTL pulse is used, which will only be about 3V, these are matched at 4µs each. (ii) Alternatively, if a trigger pulse is not available or exact timing is not crucial (for instance when lesioning or injecting dye, there is a jumper which can be set to allow the unit to deliver a current for the duration the single shot button is held down. The internal SINGLE jumper determines the output delivered when the SINGLE button is pressed (when EXTERNAL Duration is selected). MON (factory setting) produces a very short pulse ~10µs when pressed. CONT produces an active output for the duration of the press. This could be useful in dye marking etc.
Can I control the DS3 or DS2A using a computer?
Yes and no. The DS3 features an external GATE input allowing externally derived trigger pulses to define stimulus duration. However, the output amplitude is always determined by the front panel setting of the stimulator. We recommend our NeuroLog system to those interested in using a computer generated waveform to define stimulus timing/polarity and strength.
I can’t decide between the constant current DS3 and constant voltage DS2A MkII- how should I choose?
The visible difference between the two units (apart from the colour!) is that the output control of the DS2A is defined in Volts while the output of the DS3 is defined in Amps. The actual stimulus passing through your preparation is measured in Amps in both cases and is dependent upon Ohms Law (V = IR). If your preparation has a variable impedance (R) and you are using a constant voltage (V) source such as the DS2A, then the actual current (I) passing through the tissue may vary considerably between each stimulus, which may not be a good idea if you want to apply reproducible stimuli. With the DS3, the constant current circuitry prevents variations in tissue impedance from altering the size of current applied (within the 90V compliance limit of the unit), leading to the stimulator equivalent of WYSIWYG – “What You Set Is What You Get”. Unfortunately there are no well defined rules governing the circumstances under which either stimulator should be used. If you are not sure and feel the need to evaluate either or both please contact us.
If the DS2A or DS3 is connected to the TTL generating device which is grounded, will the stimulus delivered be still isolated? In other words, would it be safe to use it with patch-clamp, or there is a risk of destroying of the patch-amplifier?
Absolutely. The output of the DS2A or DS3 is optically isolated from the trigger inputs, so there is no need to worry about what your trigger source is, or how it is grounded.
Can the DS2A, DS3 or DS4 be used to stimulate human subjects?
Neither the DS2A, DS3 nor DS4 have medical device directive (MDD) certification and have not been designed for safe human use. We offer a range of medical device compliant stimulators for patient connection as well as a range of stimulators designed for safety in human research studies.
What is the maximum trigger rate of the DS2A or DS3?
The unit can be triggered fast enough to allow >99% “on” time, but the “off” time must >20 microseconds – so, very fast!
I would like to stimulate neurons using 20V 1ms long pulse applied at 10Hz frequency for 30 seconds. Such train should be programmed elsewhere as a train of TTL pulses and delivered to the stimulator, am I right?
Correct, you should program your DAQ interface to deliver trigger pulses @ 10Hz for 30s via a digital output. The DS2A will trigger on each rising edge and the stimulus duration will be set to 1ms using the controls on the DS2A front panel, with the voltage set to 20V.
I have an old DS2 constant voltage stimulator and I recall that Digitimer offer a conversion to constant current. Is this still possible?
No, Digitimer no longer offers this service. Since the introduction of the new DS3 constant current stimulator, this unit is now offered to customers requiring a constant current version of the DS2A.
Is it possible to use two DS2A stimulators in series in order to stimulate through the same electrodes with different pulse types?
Yes, this is quite simple to setup and has been summarized in an application note available in the downloads section.
What is the frequency at which the pulses are delivered when the trigger button is pressed in conditions when jumper is set to cont?
The trigger button has no effect of trigger frequency. It is designed to allow the user to press and hold the Trigger Button to deliver a continuous single stimulation pulse while it is held down. This can be useful for electrical lesioning of a recording site once an experiment is complete.
Are any of your stimulators MRI compatible?
Our stimulators are not classed as MRI safe, as all of them contain ferrous materials which means they cannot be used within a magnetic field. However, as long as they are located beyond the reach of magnetic field or in the scanner control room they may be used. It is important that MRI compatible electrodes and cables are used within the scanner room.

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