I know that when you run a Bluetooth module from the 3.3 volt pad, you have to add a capacitor between the 3.3 volt pad and Ground. My question is, do I need this capacitor for a spinning crystal chamber motor?
My plan was to wire it with around a 50 ohm resistor so the motor gets between 1.5.and 2.0 volts, then trim the final spin speed with the blade style.
Has anyone else done this and can they confirm I’m thinking along the right lines?
A link for the motor is below and includes specs for it:
Thanks as always.
Motors are coils. Coils are the enemy of reliable electronics.
I don’t recommend hooking up a motor to the 3.3v rail, hook it up to the battery instead. (And add a resistor if you need it.)
Adding capacitor helps, and very rarely hurts, but I’m not sure if it is needed when hooking up the motor to BATT+. If still choose to hook it up to 3.3v, then yes, I would absolutely add a capacitor.
My reasoning for using the 3.3 volt pad was to ensure consistent motor spin speed. If Batt+ varies between around 4.2 volt and 3.2 volts, wouldn’t that give different spin speeds depending on battery charge level?
Yes, the changing voltage will affect your RPM…but the voltage from your battery should not dip below 2.5V before you have to recharge it. According the to specs on TSA even at 1.5V the RPM is still 20.
If you really want constant speed, you could put a small voltage regulator in place like this one from Pololu: Pololu 3.3V Step-Up/Step-Down Voltage Regulator S7V8F3
That will keep the voltage constant even if the battery drops below 3.3V.
As a side note, Pololu makes many neat little boards, and they are all sized for small hobby projects. They use high-quality components and all the boards are well designed. More expensive than the Chinese crap you can get on Amazon or Ebay, but worth the price difference IMO.