AddOhms Topic Request

Use this thread to request topics to be covered on AddOhms.

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Hello, I’m a student in China, can I use one clip in your video for a science video competition? :slight_smile:

How do you plan to use it?

I need to make a short video about electricity and Mr. Tesla, and I want to use your clip (about a few seconds) as a background. the video will be used for an online competition. can I use it?:slight_smile:

Sure. If possible, reference “” or “” as the source.

thanks:smiley: u are so cool

Trying not to make this request project specific, but I keep encountering it and not learning from my reading of stuff on the web and it never sinks in at a level when I understand.

This request is basically “how to manage a project where multiple voltages are used within the one project?”

It comes about from trying to build various Arduino projects where the MC only needs a small 3.3V, However, a good amount the sensors, breakouts boards and other "stuff"you’d want to use, require a power supply of 5v or more.

My current small project is to monitor the pool water level using the Milone E-Tape sensor.
I’m using a moteino as the low power MC via a 3.7V Li-Ion battery and this is to last a long time.

The sensor board (spec doc link) needs 6-30V DC, and I figured I’d use a 9V battery and somehow activate it’s power supply via a MOSFET or something, read the sensor level and send it to the IoT gateway, and shut it all down again for sleepy time until the next read in a minute or so.

I keep getting hung up on the controller side having to deal with the “do-er” side of the things that frequently operate at higher voltages than the MC. Eg, an arduino controlling a set of servos and a range of lights / LED digit displays in a home cockpit project and needing a chunkier power supply for those servos and lights, of which would would larger than the power supplied used by the arduino.

I know there is a whole heap of ‘gotchas’ that need to be kept in mind for things like this (common grounds, avoiding the ardunio being backwards powered across the controlling pin) and other stuff. :confounded:

Love the vids @baldengineer! Just subscribed after stumbling across the 100K sub special - congrats!

I like the idea. I briefly touched on it in Bank to the Future. It’s a capacitive sensing coin bank I built for element14. I had 3.3 (ish), 3.7, 5, and 12 volts in the same design. I’m thinking the “gotcha” aspect goes well with “Using dividers as a regualtor?!” video.

I’ll add it to my list. Thank you for the suggestion.

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No probs. Just watch the element14 vid and that found that it was a great little project! Makes me want to do something similar where you can just dump the coins in your pocket after work and let the device count and store the details.

Finally, I see what you mean if your previous reply when you mentioned you ‘touched on it’ You just can’t stop with the puns can you? (Love it!) :rofl:

If it helps here’s how my worries over this mixing voltages issue:
While I know I generally should try to search out other ways to do to the project with 1 voltage, sometime the desire to run off a battery and sleep most of the time is too appealing for a project.

I keep thinking I’m over complicating the project with throwing all these various breakout board and parts I’ve learnt along the way. It seem like I’ve tied myself in knots when I’ve tried to implement all of the below just to have a 3.3V MC talk to a 5V servo or sensor.

  • Bi-directional Logic changes

  • Mosfets and other transisters. Although I’m still too scared to commit to implementing these simple options. The lack of confidence, despite repeated readings on how they work (including your videos) and testing the ideas on breadboards, mainly comes from seemingly everyone having a caveat of something that will negatively effect a project.

  • buck and/or boosting power to get the correct voltage to required by the sensors and servos. I mainly thought of these as something that I’ve only consider with a mains powered project, but your E14 vid gives me other ideas - so thanks for opening up those options. The only catch is that I still need to work out ways to use MC controlled ‘switches’ so these don’t have to be powered all the time. and them I’m back at the top of the list. :weary:

Anywho - sure you’ve got plenty of info regardless of my prattle. Good luck and I’ll look forward to the next video. Once I’ve good through all the old ones.

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I like very much your video and am searching for an solution for the following challenge.
I have a HV 400VDC battery with 75kWh what can discharge up to 350Amp. Now I would like to learn how to limit the current down to max 30amp so I can discharge the HV 400VDC into a solar inverter with MPPT.
Any idea?

Sorry. I don’t have enough experience with that kind of power to provide a suggestion.