# Bench power supplies output

This is maybe a silly question, but when a lab bench power supply has 2 output channels that are both adjustable, can each channel be set at a different voltage than the other?

Like this one provided by the link, can channel 1 be set to 24V and channel 2 be set to 5V simultaneously, with both negatives tied together for a reference?

• Yes, the voltages can be set independently. Some units allow them to track each other, with opposite polarity -- nice if you need $\pm 12\:\text{V}$, for example. Most of my supplies here are triple-output and support setting up two of them as tracking, or independent, as I may desire. – jonk Apr 2 at 22:48
• @jonk Ok thanks. If you leave an answer I will accept it. – David777 Apr 2 at 22:50

In this particular case, the answer is yes regarding two independent supplies. There are a number of indications to examine. One is that the display shows both channel 1 and channel 2. That's a very strong indicator, as they wouldn't waste the space or cost unless that's exactly what is needed when using the device. Another is that there are separate course/fine adjustment knobs available, for each channel. Finally, you can see separate outputs for each channel. This isn't, by itself, definitive. But usually it is cheaper to just make a single output capable of more current. I'd be very surprised to see that kind of output layout if they weren't separately settable.

In general, when you see separate displays, separate knobs, and separate outputs then you have enough to be pretty sure that the outputs are independent.

The answer is also yes with regard to being able to tie the two negative rails together. That particular supply states that the supplies can be used in series or parallel.

Some power supplies allow "tracking," which just means that you only need to set one of them and the other one will "track" it. This is used for bipolar power supply needs, where $$\\pm 12\:\text{V}\$$ (for example) is needed. However, you'd need to either check the manual or else do some very careful reading of the front panel to look for indications in order to know if that feature is available. For example, on my Tektronix PS2520G power supply it shows "MASTER" and "SLAVE" underneath the outputs. That's the kind of thing to look for if you hope to get a tracking supply. See picture below:

(I used an odd lens effect here. But you can see the labeling easily.)

The Tektronix PS2520G power supply supports GPIB commands as well as front panel operation. The supplies can be set so that they float or they can be set so that they are ground-referenced. Some details about this are shown in the manual, parts of which are included here, below:

As you can easily see, this power supply is quite flexible. I'm a semi-dedicated, wanna-be hobbyist. So I look for instrumentation like this.

• If I had dual output power supply of 12V on each output, could I link these outputs to get 24V (for example). – ChrisD91 Apr 2 at 23:20
• @ChrisD91 Depends upon the supply. Unless you pay good money, the usual answer would be "no." In the case with the PS2520G from Tektronix, the supplies when set to "independent" (or "isolated ground") are entirely isolated and I can place them in series or in parallel. They can be set to ground-referenced, too, though. (I have three of these supplies, which I picked up at the Tektronix store for a "very reasonable" cost.) Look at the picture and see the PARA/INDEP in Blue? I use the SHIFT key on the right to access that. – jonk Apr 2 at 23:28
• Yes. Quote: "Series and parallel connections" – AnalogKid Apr 3 at 0:01
• @AnalogKid Yes, that's true for the OP. However, it was ChrisD91's question to me and I didn't assume that Chris's "if I had" question referred necessarily to the OP's choice. So I answered more generally. That said, I could have been clearer in writing. – jonk Apr 3 at 0:08
• @AnalogueKid as Jonk stated i was looking more for a general answer – ChrisD91 Apr 3 at 3:35