I am hoping to build a spinning LED gadget using some strip lighting RGB LEDs and a quartz clock mechanism. I would like to use this small project to increase my electronics knowledge so I just have some questions regarding my project that I would love some advice on. I would like the following features on this gadget:
Battery powered so it doesn't have to be plugged in to work (portable)
If left on for a long period of time, and the batteries are drained, I would like to be able to charge the system without having to disassemble anything/remove batteries (e.g. plug in 5V micro USB to charge).
The user can twist any one of 3 rotary potentiometers to change the color of the LEDs
A simple on/off switch turns on both the quartz clock and the LEDs
I would like to reduce down the space required by the electronics to achieve this as much as possible
The main questions I have are the following:
Is there a big difference between 12V and 5V strip lighting LEDs? I don't need this as a light source, more so a decoration. What would you recommend?
I have used LiPo batteries in the past - is 11.1V from LiPo batteries adequate or would I need 14.8V + a 12V Voltage regulator to power 12V LEDs? (Similarly for 5V, is 7.4V LiPo + a 5V voltage regulator required?)
Battery charger - is a battery charging PCB + LiPo battery the easiest way of achieving this or what is recommended to have the ability to recharge the batteries without removing the battery from the system?
Are buck converters the easiest way of stepping down the battery voltage to 1.5V for quartz clock and 7V for micro-controller controlling LED color? (Assuming micro-controller needs 7V input)
I have seen some tutorials online using pots and 10K resistors with an arduino to control the LED color - are these the only hardware components required to achieve this for 5V LEDs? For 12V LEDS, do I also need 3x transistors?
What is the smallest micro-controller that is still compatible with arduino that I could use for this project? I will consider anything that is under the $20 price range
As mentioned, I would love to know what the most suitable hardware is to minimize both space and cost. I don't expect anyone to answer all of the above questions - just hoping that if you have any thoughts/experience on any of the questions I have, you can please share them here.
Is there a big difference between 12V (12 Volts) and 5V (5 volts) strip lighting LEDs? I don't need this as a light source, more so a decoration. What would you recommend? There is, that is what the 12V and 5V tell you. It depends on your design, I prefer 12V.
I have used LiPo batteries in the past - is 11.1V from LiPo batteries adequate or would I need 14.8V + a 12V Voltage regulator to power 12V LEDs? (Similarly for 5V, is 7.4V LiPo + a 5V voltage regulator required?) This is an open ended question in that do you want full brightness from the leds. They will be dimmer and last a lot longer at 11.2 volts as well as require less current. Although it takes more current I am a fan of using the on board regulator, the additional filtering is a big help. Remember an Arduino is not a power supply.
Battery charger - is a battery charging PCB + LiPo battery the easiest way of achieving this or what is recommended to have the ability to recharge the batteries without removing the battery from the system? This is a personal decision. You can go either way. This is a design parameter. Remember it is easier and safer to use an external charger for the LiPo batteries.
Are buck converters the easiest way of stepping down the battery voltage to 1.5V for quartz clock and 7V for microcontroller controlling LED color? (Assuming micro-controller needs 7V input). Yes; but you can use the on board regulator and not worry about the 7V, just feed the board with your battery at Vin (NOT 5V or 3.3V).
I have seen some tutorials online using pots and 10K resistors with an arduino to control the LED color - are these the only hardware components required to achieve this for 5V LEDs? For 12V LEDS, do I also need 3x transistors? It depends! How much current do you need for the LEDs, if you need more than 10mA use power MOSFETs rather then transistors although transistors will work but you will lose between 0.7 to 1.4 volts depending on the transistor chosen. If you do not want to constantly replace LEDS the resistors or current source/sinc are mandatory. The choice of 10K for the pots is fine. The resistors are i assume for the LEDs, use an online calculator or Ohm's law to calculate the resistor value, this will take care of the forward voltage drop of the LED. To be safe remember no more than 10 mA per micro pin.
What is the smallest micro-controller that is still compatible with arduino that I could use for this project? I will consider anything that is under the $20 price range. I assume you do not have the ability to use DIE so one of the 8 pin devices will work. Consider the 8 pin ATtiny.