UniPowerSupply – an LM2576 based design

I ordered boards to test a new power supply design.  It’s based around the National Semiconductor LM2576.  This accepts 7v to 40v as input and uses switching to produce a stable 5v output.

One of the things that became apparent to me as I worked on TinyTimer and TinyPLC is that a USB power input wasn’t always convenient.  I still think it is a great power source for small electronics.  The wall transformers are plentiful, cheap, and have a very easy to find cable that is very durable.  All qualities that are optimal for small embedded projects.

However, in some control applications it would be convenient to use whatever DC power is handy.  A rectifier could be added in some cases to deal with AC sources like 24vac which is very common.

I am also looking at the LNK306PN which is essentially a power supply on a chip.

Here is an image of the prototype / testing board:

unipowersupply

TinyTimer KickStarter Edition is code complete

I wrapped up the code for TinyTimer KickStarter edition.  This completes the project and paves the way for units to ship.  It has several unique features that are missing from similar units on the market.  These features include:

  • Arduino IDE compatible for education and hacking
  • OpenSource Hardware design with Eagle files available.
  • Push Button programming and easy to use jumper for run/program mode.
  • Natively supports time periods of deciseconds (1/10th second), seconds, minutes, hours, and days.
  • Allows periods to be mixed for significant flexibility.
  • Supports values of up to 9999 for deciseconds, seconds, minutes, and hours.  Days are limited to 490 based on limitations in 32 bit unsigned long numbers.
  • Example applications:
    • Run a pump for 1 hour per day, or per week.
    • Flash a light for 2.5 seconds once per minute.
    • Run a device for 2 hours once per 30 days.
  • Kit price is expected to be $55 with a fully assembled and tested unit for $75.  Shipping not included.

WP pasted back together.

Still not really sure what went wrong or what fixed it, which is spooky.  But it seems to be working now.  I switched themes a couple of times and it started working.

2AA batteries for breadboarding

I created a part in Eagle for a 2 AA battery holder.  Ordered a set of prototype boards.  Cute but kinda pricey.  Need to validate the layout and hole sizes are correct anyhow.  Will be nice to be able to put 2 AA batteries on the breadboard.

oshpark-2aabattery

Simplight and prototyping

I started working on a new project tonight.  I’m going to build a compact, cheap LED light that runs on a single AA battery.  I’ll be using the MCP1640 voltage regulator booster from MicroChip.

I created the Eagle-Layout for it tonight and ordered a test board from OHSPark to verify the layout.  I also created a SOT23 to breadboard adapter and ordered 3 of those as well.  That will make it easier to prototype the chip and figure out how to set it up.

I also made a variant of the TO92 package for Eagle.  I find it annoying to bend the pins for transistors when putting them in boards.  I can’t think of a good reason it’s needed so I built a straight layout for the BC517.  I added it to the test layout board that I ordered.

MCP1640 breadboard adapter
MCP1640 breadboard adapter

Test board to verify component layout.
Test board to verify component layout.