Wednesday, August 13, 2014

The Smallest Arduino Clone Possible

Everybody are making Arduino clones. So I thought I should make THE smallest. I took smallest package atmega88 – 28qfn (5mm x 5mm). Routed smallest possible resonator and as much pads as i could fit on in. The result – Smallest Arduino clone ever! Size is only 7.4mm x 7.4mm! Features include:

  • Auto reset
  • UART
  • SPI
  • 4 analog channels
  • 1 digital i/o
  • one LED
  • funny readme with BOM
It needs arduino bootloader for atmega88 like ottantotto bootloader, probably it needs some hacking too because the resonator is 8MHz not the Arduino regular 16MHz. [Link]

Voltage Converter 0 5v to 6v Circuit Diagram

This is a Simple Voltage Converter 0.5v to 6v Circuit Diagram. Conventional silicon transistors just cant operate at voltages less than about 0.7v. Old germanium transistors could be used, but those are hard to find these days and most are rather large in size. Some new n-channel MOSFET devices with very low gate-source threshold voltage can operate at quite low voltages. Ive been experimenting with various devices and came up with one electronic circuit (shown below), which demonstrates how to boost the low voltage from a single solar cell to a higher voltage. 

Voltage Converter 0.5v to 6v Circuit Diagram

Simple Voltage Converter 0.5v to 6v Circuit Diagram

The key component in the circuit below is a cheap single logic device from Texas Instruments. It turns out that TIs 74AUC family of parts can work down to about 0.45 volts. I tried one of their single schmitt trigger parts and found I was able to make on oscillator function nicely at 0.5 volts. I then used a charge pump technique and a cheap NPN transistor to form a low power flyback converter. 

This hobby circuit can produce about 6 volts at the output from a 0.5v input. The idea is to use this boost circuit to generate the higher starting voltage needed by a much more powerful DC to DC converter. Once started, part of the converters output could then be feed back to the input, to sustain converter operation. This is known as a "bootstrap" technique. In the future, I hope to post a circuit which can supply several watts of power from a 0.5v input voltage. This would be ideal for charging a battery using power from a single large solar cell or several smaller cells wired in parallel.

Drown By : Dave Jhonson