Capacitor for bluetooth using the workaround "route"

Hello @profezzorn ,

You had informed me to use this:

But I was reading in the deep sleep thread about the bluetooth workaround:

I would like to go the with the workaround route and have my BT909 as a “fake blade”. So do I need 22uF, 47uF or 100uF for that ? What would be the difference ?

Also about the voltage rating, 6.3 to 10V, this is the recommended range. Would it be a problem if it was more: 20, …, 50V or more? What is the maximum that would still work.

I am asking this because the ideal 47uF 6.3 to 10V ceramic capacitor (603 or 805) is only available in Malta at an atrocious shipping price, unless I order minimum 3000 of them ! 20€ for 100 pieces + 22€ shipping + import tax on parts AND SHIPPING (yes I have to pay tax on the price of shipping !!!). I refuse to pay that much for a less than 1€ part that I only need one of them.

My local electronic repair shop has offered to look for a salvageable one from discarded electronics. So I would like to know what is the min-max uF & V that could be used ?

Thanks

The voltage rating is a maximum, so anything above the maximum is still fine, so long as the footprint (0805 or 0603 since they’re similar enough in size) is correct, uF is all that matters.

The point of the capacitor is to act as a mini battery whenever the Bluetooth powers on, otherwise it (often) pulls more power from the main power line than the board can handle, resulting in the board crashing. So yes, it’d be ideal. With some of the smaller BLE modules people have gotten away without one though, and sometimes because the chip isn’t starting up as the same time as the proffieboard, when BLE is on a separate blade they can also get it to work, but it’s a pretty fine line and you’re better off just having it.

Think of the different uF ratings as different battery sizes. The bigger the “battery”, the more power it can provide to the BLE to aid startup.

Cool, so the bigger (uF) the better ?

Within reason. Just stick within that range and you’ll be fine. Closer to 47 is more ideal.

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Your answer is in Proffieboard User Manual PDF on page 19, please take a look: ProffieBoard_v2_User_Manual_07.pdf - Google Drive

Also you don’t need that capacitor if you are using the big BT909 module on black pcb with leds and pads (from TCSS, SaberBay, KRsabers) because that pcb already has that capacitor.

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Yes it is indeed the “big” BT909 on black pcb from SaberBay.

That is great news. I can finally continue to solder my Proffie board to the rest of the chassis.

Thank you.

No kidding? What the hell do I do with all these capacitors now?

Seriously though that’s great.

How many capacitors did you get ?

extra capacitor won’t hurt :slight_smile:

Lil bag of em. I’ve got plenty if you need some. I only use them for bt.

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Thanks, I only needed 1, but now I need zero. Good thing I didn’t order 100 of them.