[WIP] Best practices to power your nodes

[Daniel Oliveira]

Hello all,

I think that good quality power source is a very important aspect to have a stable MySensors network or any other projects.
In this forum there are a lot of people facing problems that are solved by improving how they power their projects, but despite that I think that all related information is scattered in the forum and not always easy to find or to relate.

So, why not bring this amazing community together and point here some good practices on how to power our nodes?
I would like to start this by addressing first two topics, "approved" power adaptors and bypass capacitors.

Power adaptors:

• Cellphone chargers
• HLK PM01 (toAddLink)
• ToBeCompleted

Bypass Capacitors:
(What is a bypass capacitor: http://www.learningaboutelectronics.com/Articles/What-is-a-bypass-capacitor.html)

• NRF24L01: To discuss in this thread
• ESP8266: 470uF as close as possible to Vin and GND pins

Please add your opinions and knowledge about this topic, my goal is to keep this post up to date with shared information.

For example, what are the values that you recommend for the NRF24L01 and why? I saw people mentioning 4.5uF, 10uF and 47uF. Personally I'm using the latter and I have no issues.

Thank you all.

[sundberg84]

Also alot of problems is not what you power your nodes with but how you do it. For example powering a nrf24+01+ pa/lna from the arduino vcc might sometimes be a problem. This is interesting for me how to optimal power a nrf radio. Myself I use a 5v in from a USB and converting it with a LE33 to 3.3v with a 4,7uF electrolytic cap close to VCC/GND on radio.

[bjacobse]

I think you mean a smoothing cap instead of bypass cap
http://www.learningaboutelectronics.com/Articles/What-is-a-smoothing-capacitor

The smoothing cap for NRF24L01+ VCC/GND is not an exact science, it depends of the quality your power source can supply.

If you have a battery operated device, you might not need it at all. battery is a large cap. and if using in battery operation your MCU/NRF is sleeping most of the time, and only transmitting shortly, and then sleep again to save battery lifetime.

When using a AC230V -> 5 or 3,3V most converter are DC/DC and the DC signal is not smooth like a battery, to help and get this voltage signal better you need cap. The closer to NRF24L01+ VCC/GND the better. I don't believe that cheap power supplies from ebay/China are providing quality voltage...

The cap size is most likely depending on how you again are using your NRF24L01+, is it continuous receiving and transmitting - like a repeater node, I recommend a large cap, if it's only transmitting occasionally and not a repeater node, you can use a smaller cap.

The final cap size is usually what you have in your drawer + that can fit into your plastic housing