I teach at a community college, lecturing daily with slideshow presentations (which mostly originate from the textbook publisher). The classrooms where I teach have a lectern computer with an overhead projector.

Unfortunately, the lectern computers were all installed in a way that they only have a single video output, and the projector can only show a duplicate of what's on the lectern monitor itself. (My understanding is that a cheap video splitter was used instead of two separate monitor outputs.) Therefore, it's impossible to make use of the standard slideshow-presentation "presenter view" feature (where the audience sees one thing on the projector, while the presenter sees notes, upcoming slides, timer, etc. on the lectern monitor).

I've inquired about getting this fixed numerous times, going back over a decade now. I'm possibly the only person in my department who uses presentation slides -- it's still considered novel and unusual -- and I don't think anyone I've ever spoken to understands what the issue or "presenter view" is. So, I see no sign that the hardware issue will be fixed.

Thus, I'm looking for some way that I might be able to jury-rig an effective second monitor temporarily while I'm class. I have access to the computer tower under the lectern, and can plug in USB devices as needed (routinely use a memory stick, digital clicker, etc.). I don't have access to the monitor cables (padlocked at the back of the PC tower). I have my own tablet, laptop, etc. that I could bring and plug in. The school towers all run Windows. The lecterns have MS Powerpoint locally installed; but I normally I run slideshows via Libre Office Portable Impress from a USB stick. The lecterns do not have the Miracast wi-fi screen-casting software available.

At this point, I'm personally stumped. What options are there for me to plug in another device here, and get the functionality of the slideshow "presenter view", with different image on instructor monitor vs. overhead projector display?

Update: It turns out that the "cheap video splitter" story that I'd been told by IT staff was not actually correct (nor something I could verify, the way the towers are locked in place with the back inaccessible). The selected answer shows how to access the existing projector as an extended monitor in Windows, which apparently no one at my institution knew to explain.

  • 3
    have you considered bribing the IT people? Also what interfaces do they use? Can you plug unto the projector and what interfaces do they have?
    – Journeyman Geek
    Oct 2 at 23:02
  • Could you print out the extra information instead? Oct 3 at 0:21
  • The projector's installed up on the ceiling near the back of the room and so not accessible that way. Oct 3 at 1:02
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    There exists a Android app that can act as a remote to LibreOffice Impress, while showing notes on the phone screen. Might have some firewall trouble setting it up, though.
    – jpa
    Oct 3 at 16:26
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    @DanielR.Collins: Generally such apps expect the other device to be on the same IP network (and usually the same subnet, so that auto discovery would work). How the desktop PC is connected to the network rarely matters at all, as the same subnet can easily extend across both WiFi and Ethernet (just as it almost always does on home routers). Oct 4 at 4:31

4 Answers 4


Unfortunately, the lectern computers were all installed in a way that they only have a single video output, and the projector can only show a duplicate of what's on the lectern monitor itself. (My understanding is that a cheap video splitter was used instead of two separate monitor outputs.)

While a cheap video splitter is likely, that's not the only possibility – in many cases, even if two independent outputs are available they will be deliberately set to "Duplicate" mode to retain user familiarity.

Before purchasing anything, go to Settings→Display and check whether it has detected two displays or just one; if there are two – hit WinP on the lectern computer to check whether the "Extend" mode works.

What options are there for me to plug in another device here,

Bring your laptop and a HDMI capture card. Connect the capture card via HDMI to your laptop's output and via USB to the PC tower. Run something like a portable version of OBS to display the capture card's input in full screen.

I have no idea what sort of quality you'd get from a USB connected capture card (especially if the available ports aren't even USB 3.x), but for slide shows it should work.

  • 2
    You don't even need OBS - the built in camera app works. I tend to buy the cheap models (5-20 USD) and the quality is passable. If I understand correctly - you're using the laptop as a primary and the lectern PC as a output for that?
    – Journeyman Geek
    Oct 2 at 22:55
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    @Daniel: I've never seen a laptop where it wouldn't count as a second independent output. (Even the integrated GPUs already have it separate, so it would take effort from the manufacturer to disregard that and add a splitter just to get less functionality for more cost.) If it's not a matter of selecting the right mode under Win+P, then it's probably a driver issue. (But in the most unlikely case that it's really hard-duplicated, you can combine this method with a DisplayLink USB video output...) Oct 3 at 5:10
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    Got this working at home now -- I had no awareness of the Win+P project settings until you mentioned it here (now set to Extend). Using the built-in Windows Camera app on the receiving machine seems the most elegant. I'll test this on the school computer and if that works then I'll likely accept this answer. Oct 4 at 2:45
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    @Daniel: Then maybe you actually have the same option on the school computer and just never have tried it? Many such PCs just have both outputs set to "Duplicate" to make things easier for teachers who want to demonstrate things other than Powerpoint slides (and can't remember the mode-switch key for longer than a week). Oct 4 at 4:28
  • 2
    Indeed, it turns out that the Win+P projector settings does get a working second monitor state on the school computer (and hence the slideshow presenter view function). Maybe embarrassing for me -- but none of the IT staff or even the head of IT ever knew to tell me that when I asked. In addition, the laptop output strategy also works and would have been my backup plan. Thanks for this answer (and the edit after comments). Oct 5 at 4:15

I had a similar situation of needing to get presenter view in a classroom. If the computer isn't too locked down, the simplest solution is to connect a display via USB.

The most common technology used for this is called DisplayLink. It requires your IT department to install the DisplayLink driver on the computer - depending on your IT department, this may be easy or may be impossible.

There are several different ways you can add one, but the easiest is a single-cable USB display - the same USB cable provides power and data to the display from the computer. Here is an example (NOT a recommendation, just to give you an idea of what it might look like): https://www.amazon.com/AOC-I1659FWUX-USB-Powered-Portable-1920x1080/dp/B06X9C6XFK/

If you already have another monitor that you don't mind carrying around, you can get a DisplayLink HDMI adapter (or DVI, VGA adapter, if your monitor is older). It is probably much less expensive, and it works the same way except that you'll need a separate power cable for your monitor.

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    DisplayLink is a great option, and I think that modern Windows might even come with the drivers preloaded, or at least available through Windows Update, so you don't have to download and install anything yourself. Whether or not this would work on a presumably locked down machine I can't say.
    – josh3736
    Oct 3 at 5:32
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    As of Windows 10, it is standard and part of Windows by default, so it worked out of the box with my wife's locked down computer from school. Test first though, because they can go out of their way to remove/disable the drivers if they feel like it. Definitely need to be installed on Windows 7.
    – Nelson
    Oct 3 at 6:13
  • This was the idea I'd come to post, too—I picked up one of these types of monitors (ASUS MB16AC, in my case) while working from home early in the pandemic, and it was surprising to me just how well it worked. Oct 3 at 15:01
  • Don't those USB monitors all require USB 3 (or maybe even higher 3.x versions)? The lectern computer might be too old for that or those ports might not be exposed. OP also said they have no access to the monitor cables, which might mean they can't connect additional video cables, if the computer even has additional video ports available.
    – gre_gor
    Oct 3 at 22:22
  • @gre_gor I have used USB 2.0 DisplayLink devices in the past - they do exist, they might just be a little harder to find now that USB 3+ is common.
    – Moshe Katz
    Oct 3 at 22:26

Having worked in IT in education, you're quite a distance from the "regular" user level. Academics come in all technical skill levels, which don't correlate with their talent nor their teaching ability.

Your question has two parts - How to get your classroom gear to work better for you, AND without messing up other users of the same equipment.

If you want to effect change across the whole organisation, then you'll need to get included in budget/planning for IT and have a Proof of Concept. Only once the merits of the new-way are seen will anyone understand what your goal is.

If you had your own teaching room then it would be much easier, but sharing the space with others makes it hard.

  • From the college's point of view, the easiest solution is a complete duplication of gear that you bring in and set up as needed. This allows other room users to work with the setup they know. Downside is the cost of additional equipment, and the setup/knockdown time along with wear and tear on moving it all.
    If you could access the cable that goes from the lectern up to the projector, and move it to your own laptop then that could be sufficient. Just remember to return it to original when you finish.

People can be resistant to change - if they see the New Setup as having to rework all their slides, then it brings a negative reaction. Instead - you need to show the positive benefits to them.

In a perfect solution, this could be done during a hardware refresh, providing new functionality with a keypress but defaulting to the old duplication setup.

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    Another education IT worker here... years back we used to have manual audio/video selectors between the room PC and a DVD/VHS player. The largest instructor complaint in the rooms was when one instructor used the DVD player, the next person in the room often lacked the technical ability to identify what had happened and just set the dial back to the position labeled "computer", and would instead open a ticket. Oct 4 at 16:58

If you're able to install software on the machine, another option is Spacedesk, which allows you to use another device as an external monitor over the LAN or USB.

There are client apps for Windows, iOS, and Android, so if you already have a tablet, you can use it as a pretty good monitor.

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