The Constant Voltage Stimulator - Unipolar Pulse (STM200) can be used to stimulate any preparation or subject, including
pain and stress studies that require lower voltages and wider pulse widths
trigger the stimulator from a visual presentation system such as SuperLab®, E-Prime®, DirectRT®, MediaLab®, Inquisit®, and other visual presentation programs
tissue baths (range 0-100 V at 0.1-200 ms pulse width)
nerve or muscle stimulation that requires higher energy than a STMISOC/D/E can deliver
Controls & Connections
Front Panel
Range
Establishes the stimulus pulse output level range in Volts (0-10 Volts or 0-100 Volts).
Turn right to select a range of 0-10 Volts.
Turn left to select a range of 0-100 Volts.
Remove the key for added safety and control.
If the Range is changed before recording begins, the scaling must also be changed (MP menu > Set Up Channels) to maintain direct Level recordings.
If the Range is changed during recording, the user should manually enter a software marker to note the change (F9 on Windows or Esc on Mac). The pulse Level could then be determined by (mentally) moving the decimal place to the right or left, depending on how the Range was changed.
Reference
Refers to the pulse width of the signal on the Reference Output (on the back panel).
Actual reflects the actual output width.
Fixed (15 ms) establishes a pulse width of 15 ms, regardless of the actual pulse width.
The Reference control only affects the pulse width; in either case, the pulse level reflects the actual output level.
Level
Level is used in conjunction with Range to set the stimulus pulse output level. Turn the Level control (right to increase, left to decrease) to establish the desired Level, as indicated on the digital display.
Output
Standard BNC connector to output the stimulus pulse to external electrodes or other devices.
LCD light
The red LCD is activated when the DC adapter is plugged in and the power switch on the back panel is turned ON, and flashes when the stimulus pulse is active.
Back Panel
Power
Rocker switch for turning the STM200 power ON and OFF.
Fuse
If the fuse blows and must be replaced, use a screwdriver to open (counterclockwise) and close (clockwise) the fuse cap.
DC Input
Socket for DC adapter (AC100A).
Trigger
This cable terminates in a 3.5 mm mono plug for connection to the UIM100C Analog Output 0 or the STM100C 50 ohm output.
Manual Test
Used to diagnose problems with the STM200 stimulator unit. When the Trigger and Reference Output cables are disconnected, press the Manual Test button to initiate a stimulus with a fixed pulse width of 2.5 milliseconds.
Reference Out
This output cable terminates in an RJ-11 plug for connection to the HLT100C. The cable reports the stimulator marker pulse to the MP System, via the channel it is connected to. A marker pulse will be generated each time the stimulator generates a pulse. The front panel Reference switch determines the marker amplitude:
Actual varies between 0-1 V and maps to 0-100 V or 0-10 V
To use the STM200 as a stand-alone stimulator from the MP System, the user must supply
TTL high pulse to the tip of the mono phone plug connector, with respect to the plug shield.
Power (+5v and GND).
Signal conditioning to the output to observe results.
The report signal can be observed via the RJ-11 cable. The Reference Output cable does not need to be used for STM200 operation, because the front panel LCD panel indicator will show the pulse height output and the pulse width will simply be the pulse directed to the STM200.
Software Setup
The stimulation waveform must be created using stimulator setup (MP menu > Setup Stimulator). The output waveform should be designed so that it has
one or more pulses
baseline of 0v
pulse amplitude of 5v
pulse length from 0.1ms to 200ms
related pulse duty cycle should not normally exceed 10%; higher duty cycles are supportable in certain circumstances.
Calibration
The Reference Output signal should be calibrated to optimize results.
With the STM200 connected and ON, turn the Level control counter-clockwise until the display reads 0 (or as close to 0 as possible).
MP menu > Set Up Channels > Setup button for the stimulator channel.
Press Cal1 to get the signal representing 0V out of the stimulator.
Add the Input value found with Cal1 to the Input Value displayed for Cal2.
For example, if you pressed ‚Cal1‚ and got an Input Value of .255 mV, you would then add the number .255 mV to the existing 50 mV and manually enter the total value of 50.255 mV for Cal2 Input Value.
Note—Even if the Cal1 Input Value is negative, you must still add‚ it to the number for Cal2 (which essentially subtracts it) to arrive at the proper value.
Click OK to close out of the Scaling window and then close out of the Setup Channel window.
Optional: You can save the setup as a Graph Template to save these new scale settings. As long as neither the MP30 nor stimulator changes, the calibration should not need to be repeated.
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