Powering Up The Hydra

Setting Manual Operation Of The Hydra

         Here is the Hydra DAU.

Turn the Hydra on.  That's not a facetious statement.  Depress the green button at the lower right of the instrument's front pane.  And be sure it's plugged in.  The Hydra will go through a start-up sequence (green LEDs will flash on the front panel) and it will come up in the mode it was last in before being turned off.

The Hydra may come up in a monitor mode.  That means it takes repetitive measurements - which might be voltage, temperature, etc. on a particular channel - and it will start that operation.  If it comes up in monitor mode - and you will know that by it's efforts to take measurements repetitively - depress the white MON key in the lower right corner of the front control panel.  That toggles the Hydra out of the monitor mode.

        Next we will walk through the process to set the Hydra to measure DC voltages.  Here are the steps.

While not in the monitor mode, depress the FUNC key at the top left of the front control panel.  You should see the words SET FUNC in small green illuminated letters on the display panel.

Now you can cycle through the different functions - the operations the Hydra will perform - by using the arrow keys on the front control panel.

Cycle through to get V DC showing and depress the ENTER key to set the function to DC voltage measurement.  If you want to make another kind of measurement you would choose that measurement at this point.

• If you want to measure other quantities - like resistance, frequency, or even temperature - you can set the Hydra to measure those quantities.  Observe the possibilities as you cycle through the possibilities.

• Now, select the channel on which you want to measure the DC voltage by using the up and down arrow keys.  The left and right arrow keys will not change anything and you must use the up and down arrow keys.  Press the ENTER key when you have the channel selected that you want to use.
• The front panel terminals are Channel 0.  You can use those terminals for any measurement except temperature.

• After you depress the ENTER key you can either set the scale (e.g. 0-3v, etc.) or you can let the instrument autoscale itself - choosing the scale on its own.  If you want the instrument to autoscale, choose AUTO using the up-down arrow keys.  (The left-right arrow keys won't work here!)

• At the point the instrument is configured to take measurements.  If you want the instrument to take measurements over and over again, depress the MON key to put the instrument into the monitor mode.  It then monitors whatever it is connected to by measuring at a few second interval.  In student labs this is the usual mode of operation.

• Measurements will be taken from the front panel connections - the red and black terminals or from the channel connections on the top panel (orange in the picture).  So, connect the voltage you want to measure to the proper terminals, and the instrument will display your measurement and continuously update the measurement.

        To measure a temperature things are slightly different from what you do to measure a DC voltage, for example.  If you are measuring temperature with a thermocouple, read this section.  If you are using an LM35 or a thermistor in a bridge, you are really measuring voltage, and you should go to that section above.

        Here are the steps.

• Select the channel on which you want to measure the temperature by using the up and down arrow keys.  The left and right arrow keys will not change anything.  Do not select Channel 0.
• Note, the Hydra will not measure temperature on the front panel connections - Channel 0.  You need to choose Channel 1 or higher, and you need to connect the thermocouple to the correct connections on the connector strip.
• For a single temperature measurement (one thermocouple), connect the thermocouple to terminals 20 and 21.  The red lead on the thermocouple goes to ground (opposite of what an EE expects, but who knows who designed this system?) and that is terminal 21.
• Depress the FUNC key at the top left of the front control panel.   You should see the words SET FUNC in small green illuminated letters on the display panel.
• Now you can cycle through the different functions - the operations the Hydra will perform - by using the arrow keys on the front control panel.
• Cycle through to get ^oC showing and depress the ENTER key to set the function to measure temperatures.
• Now, you can depress the MON key, and if you have your thermocouple connected correctly you should start getting temperature measurements.

        You can make manual measurements of other variables.

• Cycle through to see the options (Ohms, Temperature in Celsius, Frequency, AC Volts) and depress the ENTER key to set the function to what you want.