Wiki recommendation for using external power with the DAQ

[ChucklesOnGitHub]

Suggestion for improvement:

The DAQ Hardware wiki page says "Voltage supplied over the DC jack should be between 5V and 12V".

This might be misleading for users that are unfamiliar with the system, since we regularly come across situations in which users plug in 9V or 12V with a standard setup and fry their miniscopes.

For the miniscope v4 perhaps the range should not be as extense, or maybe a more conservative procedure can be suggested:

Voltage supplied over the DC jack depends on setup configuration such as cable length, type of cable, commutation, etc. A good starting point would be a 6V voltage, and likely not more than 9V is needed since the required voltage at the miniscope is 5V. We suggest you use a variable power supply and closely monitor how much power is actually reaching the scope to avoid damage.

[dprotter]

In our lab we have switched to almost always using external 5V power supplies. I didnt realize the DAQ didnt have any other kind of voltage regulator to control what reaches the scope.

If you are going to suggest that users use a variable power supply and monitor what reaches the scope, please provide very specific instructions on how to test voltage on the scope side of things.

[ChucklesOnGitHub]

It would be great to have the official take on this on how to get this message across comprehensively since the DAQ is used for several devices, but in the meantime my understanding is that:

For the miniscope v4, you can read the value using a multimeter at the pads of the coaxial cable connector.

According to this forum thread, 6V DAQ external power is usually all that is needed for stable power and also avoids PCB overheating.

Once you know what you need for your setup and typical usage settings, you can always get a wall adapter of the correct specifications instead of the variable power supply.

All I meant was that if you are just going to get a wall adaptor as a power supply, see (and measure) if your system works with 5-6V DAQ external power and not 12V like the current documentation suggests.

[dprotter]

I definitely agree with your assessment on clarity, as Daniel says:

It could be very likely that applying 12V, even for a short period of time, could have damaged critical components on the DAQ and/or on the Miniscope. We have never applied 12V ourselves so I am not sure exactly what would fail first and what the resulting connection would look like.

Which contradicts the wiki, as you point out, quite strongly.

This seems like the most pertinent advice, also per Daniel in that thread:

When switching over to using the DC jack on the DAQ and sending a voltage higher than 5V to the Miniscope we still want the voltage that reaches the Miniscope not to exceed 5V by too much (and ideally this should be closer to 4V). When supplying over 5V from the DAQ you are looking to mainly account for the voltage drop that occurs across the coax cable so that the voltage the Miniscope sees isn't too low (which is usually around 3.5V).

So, depending on Daniel's interpretation, it seems like people should measure the voltage at the scope using the pads you point out, with a goal of having the voltage read 3.5-5, ideally at around 4V.

It might also be helpful to point out some power supplies that are adjustable to assist with this. We've got some https://www.meanwell.com/ but their overall voltage adjustment is small. Just around 1V.