Get ±25 volts from a DC bench power supply and easily set up symmetrical voltages

Blog Post created by StevenLee Employee on Dec 5, 2017

Typically, power supply users require only positive voltage for their testing as opposed to negative voltage. However, there are instances where you may need negative voltage from a power supply. Driving devices such as operational amplifier and transistors will sometimes require negative voltage biases. It is important to keep in mind that when we use terms like positive voltage and negative voltage, they are relative to a reference point. Voltage cannot be defined in absolute terms but instead is measured relative to a voltage reference.


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Most power supplies will not let you program a negative voltage value. This means that if you need a negative voltage, you would have to program a positive value and reverse the output to achieve the voltage that you need. This could be a bit troublesome especially if you are using a power supply to frequently power devices require both positive and negative voltage values. Keysights new E36300 quickly and easily solves this problem.


You can create up to +25 volt and -25 volt DC outputs using Channels 2 and 3 of Keysights new E36312A or E36313A bench power supplies. They can also be configured to track each other.


All three outputs of the E36312A and E36313A bench power supplies are electrically isolated from earth ground.  By connecting the output terminals as shown in the diagram below, you will use Channel 2 as your positive voltage source and Channel 3 as the negative voltage source. In the figure below, we provided an example of +18V and - 18V DC supplies.



You can use the front panel voltage knob or numeric keypad to adjust the output voltage of Channels 2 and 3.


If you need symmetrical output voltages, you can use the track mode feature, so that both DC outputs track each other.  Then, you will only need to program Channel 2 to 18V and Channel 3 will automatically be set to 18V.  Enable tracking mode by pressing Output Settings > Operation Mode >  Mode Tracking.     


Note that the front panel meter will always read positive voltage and current values for Channels 2 and 3. 


For other tips, read our application note Speed up Your Test with an Upgraded Bench Power Supply.