A.M.P.I. are the makers of the world-renowned Master-8 stimulators. Want to know what's so special about the Master-8? Read on!

This page lists the three different types of this instrument, and their stand-alone companion, the Iso-Flex:

Master-8 & Master-8-cp

Master-8 is an 8-channel programmable pulse-generator based on advanced microprocessor technology and is the most versatile on the market! Master-8 can activate up to 8 different instruments. Master-8 is a very flexible system since each channel uses its own clock (there is no use of a master clock to control all the channels). Each channel operates independently in one of several modes and can be internally connected to other channels.
With Master-8 you can easily switch your set-up between 8 preprogrammed settings by a single command. Thus several users can work on the same experimental set-up without reprogramming Master-8 each time. The amplitude and polarity of each channel are fixed by the knobs and switches on the front panel. All the other parameters of each channel and the internal connections are set by inserting the new parameter via the keyboard.

Operating Modes
Each channel can operate in any of the following modes:
Free Run: The channel generates pulses continuously. The rate and duration of the pulses can be set individually for each channel.
Trig: After triggering (manually with one keystroke, internally from other channels or externally from other devices) the channel delivers a single pulse at the preset delay and duration times.
Train: After triggering, the channel delivers a preset number of pulses at set interval and duration times. When Channel 8 is in the TRAIN mode, Master-8 automatically displays the pulse number in the train.
DC: The channel delivers a DC output independent of the time setting. The user can turn the DC output on and off manually.
Channels 1 and 2 can operate in an additional mode:
Gate: Each time that an external signal is applied, the channel operates as in FREE RUN mode. Whenever the external input stops, the channel stops working.

Inter-Channel Connections
Each channel can be internally connected to any other channel. There is no need to connect wires between channels. Each channel can be internally connected to many channels simultaneously.

 Eight Stored Settings
With Master-8 you can easily switch your set-up between 8 preprogrammed independent settings (paradigms). Each paradigm specifies the modes and parameters of all the channels and their internal connections. The switching from one paradigm to another is very fast (50 msec). All the paradigms are stored in the memory even after the power is switched off.

 Programming With Your PC (Master-8-cp only)
Master-8-cp is identical to Master-8, but has an additional powerful feature. Your PC can control the operation of Master-8-cp and check its parameters through a standard RS-232 interface. During the experiment the computer can change parameters in Master-8-cp, in accordance with the feedback from the system.

 Voltage Range
Each channel can produce output pulses with amplitudes ranging from -10V to +10V and with maximum current of 20mA.

Each channel operates within the following ranges:


Number of Pulses per Train  59,990
Pulse Duration  40 µs.  3,999 s.
Delay Time  100 µs.  3,999 s.
Interval Time (1/rate)  60 µs.  3,999 s.

Memory Retention
All parameters of each of the 8 paradigms are stored in the memory even after the power has been turned off. Since a negligible current is used for memory retention, there is no need for rechargeable batteries and their charging mechanism. Parameters are retained by an AA size lithium battery that has a guaranteed life of seven years.

 Checking Procedures
Master-8 has a built-in program which enables the user to easily check all the parameters of each channel and the interconnections between the channels.

 Multilevel Pulses
Three additional outputs deliver combined multilevel pulses:
Out 2+3 - bilevel pulses (e.g. +/- pulses).
Out 6+7+8 - 3-level pulses.
Combined Output - up to 7-level pulses.
Two Additional Clocks
In addition to its standard 8 channels, Master-8 features 2 internal clocks. The first one counts the time in seconds up to 24 hours and is used to measure the time elapsed from an event (e.g. the beginning of the experiment). The second one counts the time in tenths of seconds up to 1 hour and is used to measure intermediate times.

The TIMER can change the mode of any single channel at a fixed time up to 24 hours in advance. For example, if you want to set the experiment to stop at a given time, you can instruct one channel (or all of them) to do so.

 Rack Mounting
Master-8 can be mounted on a standard 19 inch rack.

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Master-8-vp has the same features as Master-8-cp. You can easily switch between 8 preprogrammed settings by using a single command in order to switch between different experiments. You can set all the parameters by using the front panel keys or from your PC via the RS-232 interface. You can also run the channels in the following modes: FREE-RUN, TRIG, TRAIN, DC and GATE. Master-8-vp has the same parameters and ranges as those described on the Master-8 page.

 Master-8-vp has the following additional features:

 Voltage Programmable
Master-8-vp is the voltage programmable version of Master-8. You can set the voltage output of channels 4 and 5 using the front panel keys or via your PC. (For the other channels you can adjust the voltage output using the front panel knobs).

 Increment and Decrement Steps
Master-8-vp has an additional powerful feature - channel 5 can deliver increment and decrement output voltage steps. You can set these steps in one of two ways:

 1) Fixed steps - You can set V and the number of steps per cycle. The number of steps is unlimited, the only limit being the saturation of the voltage range.

 2) Varied steps - You can set each individual step and the number of steps per cycle. You can mix depolarizing with hyperpolarizing steps. The number of steps is limited to 30 per cycle.

Fixed Steps

Varied Steps

Output Offset
You can adjust the voltage offset of channels 4 and 5 manually by simply turning their knobs.

 Output '4+5'
Output "4+5" gives you the combined output of channels 4 and 5. Thus you can get pulses in a variety of patterns, like the pattern at the top of this page, or like the following examples:

Each pattern can include fixed or varied steps.

Voltage range of channels 4 and 5:
From -12.7 V to +12.7 V.
Interval time of channel 5: 500 µs. to 3,999 sec. (more than an hour).
The parameters of all the other channels are as described in the Master-8 section of this page (see above).

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ISO-Flex - The Flexible Stimulus Isolator

ISO-Flex is a flexible stimulus isolator since:
ISO-Flex is optically-isolated.
You can switch the unit to constant current or constant voltage using the CURRENT/VOLTAGE switch.
You get bipolar pulses by connecting two isolators.


Input: 5V-10V
Voltage output: 0-90V
Current output: 0-10mA
The output is divided into 3 ranges.

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