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Product Inquiry - Need help selecting the right product
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Please be positive and constructive with your questions and comments.

Product Inquiry - Need help selecting the right product

by CarlosRR on Tue Apr 30, 2019 10:45 am

Hello,

I have a little project I want to do with a colleague and it involves using a programable controller, to control 12-16 LEDs (5V). I also want to create an app on my phone that I can use to change the lighting pattern or colors of the LEDs, so the controller would need BlueTooth capability. I want to make a few hundred of these, so the cheaper and SMALLER, the better. Any recommendations?

I will be using a 5V rechargeable battery.
I'm considering using addressable LEDs too.

I will appreciate any feedback or insight, thanks in advance.

CarlosRR
 
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Joined: Tue Apr 30, 2019 10:37 am

Re: Product Inquiry - Need help selecting the right product

by oesterle on Tue Apr 30, 2019 5:31 pm

Hi, CarlosRR!

I'd consider the Adafruit Feather nRF52840 Express,

I'd lean towards using strips of addressable LEDs, if that works for you; that would simplify your wiring a lot. One option is the Adafruit NeoPixel Digital RGB LED Strip - Black 30 LED.

Here's an example project: Bluetooth Low Energy Lights | Festive Feather Holiday Lights | Adafruit Learning System

I might power it with a 3.7V battery like the Lithium Ion Cylindrical Battery - 3.7v 2200mAh, instead of a USB battery pack. Feather boards automatically charge an attached battery when connected to a USB power source or computer port.

What are you making?

Cheers,

Eric

oesterle
 
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Re: Product Inquiry - Need help selecting the right product

by CarlosRR on Wed May 01, 2019 2:27 pm

Thanks for the suggestion, I like the nRF52840 Express but the price is almost 5 times what I wanted to spend on it. I asked for the 5V battery because just like the LEDSs you recommended, they run on 5V @2A, making them brighter than if I use the 3.7V 1.1A battery, unless I'm mistaken on this?

I am making a small device, around the size of a hockey puck, with LED's emitting light all around it's circumference. Some key factors are brightness, discharge time, and BT capability, apart from a low cost. I was aiming for under $15 in electronics, is this not realistic?

CarlosRR
 
Posts: 2
Joined: Tue Apr 30, 2019 10:37 am

Re: Product Inquiry - Need help selecting the right product

by millercommamatt on Wed May 01, 2019 3:47 pm

If you're looking for a microcontroller board with bluetooth in the $5 range, you're going to need to look on eBay or Aliexpress or the like to get cheap, off-brand microcontrollers and have them shipped direct from China.

Lithium cells have a typical voltage of 3.7 volts. So you'll need a boost converter somewhere in your design if you need 5 volts or else you need to design you LEDs to run with a lower voltage. LED brightness is a function of the current through them, not the voltage you supply. Your voltage needs to be above the cumulative forward voltage of the LEDs in series. You usually select the value of the resistor in series with your LED(s) based on the forward voltage of the LED, the supply voltage, and the desired current.

You can probably hit your target unit cost, but you'll probably have to spin up your own custom designs and have them made at moderate scale as opposed to cobbling together components you purchased at retail prices.

millercommamatt
 
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Re: Product Inquiry - Need help selecting the right product

by oesterle on Wed May 01, 2019 4:01 pm

How many do you want to make? How will they be used?

While it's possible you could get the electronics down to USD $15 in large quantities, building functional prototypes from off-the-shelf, maker-friendly parts will likely cost 3x+ that.

Other questions:
  • Could you use a smaller number of LEDs, with light piping and/or diffusion to spread the light?
  • Are the LEDs showing different colors, or the same color?
  • Does the puck house the battery?
  • How will the device be recharged?
  • What's the use case, and in what lighting conditions will it be used?
  • How long to you expect the device to run off one charge?

oesterle
 
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Joined: Tue Sep 17, 2013 11:32 pm

Please be positive and constructive with your questions and comments.