Received TinyTimer-Duo boards and then ordered a new set

I received the boards for the TinyTimer Duo… and confirmed that they too had two mistakes.  I corrected the mistakes and ordered a new set.  The following changes were logged:

  • Fixed Oscillator and capacitor sequence.
  • Added 10K resistor to reset button
  • Changed labels on logic inputs to reflect the pin they connect to
  • Changed filter capacitors on switched circuits to use the new capacitor I found from Mouser that is rated for higher voltages and has a smaller footprint.
  • Changed label on ISP
  • Added ground plane to bottom of board.
TinyTimer - Duo
TinyTimer – Duo

New Kit – Mini-button

I decided to make a small board that can be used to mount tactile switches to breadboards.  There are other products out there that do this, but most of them are not kits.  This should be a very fast “product” from design to launch.  A dozen boards are on the way.  Each board measures .34x.5 inches.  It’s designed to use a through-hole Tactile switch and standard 2 pin header.  I anticipate offering these in sets.  For example a set of 5 PCB’s or a set of 5 PCB’s with parts for assembly.  I’m anticipating that the PCB’s will be around 50 cents each.


Change of plans -ordered TinyTimerKS boards

I found a hard bug in the PCB design.  I had forgotten to include a pull up resistor on the reset pin.  This explains why it seemed dead.  There was no nice way to hack around that, so I ordered new boards right away.  Need to get a unit assembled and begin coding/testing/verification so I can ship by the end of October.

TinyTimerKS Board Layout
TinyTimerKS Board Layout

New PCB design for TinyTimer

  • replaced switch with pin-header and shunt (jumper).  This is more cost effective and avoids the switch footprint issues.
  • rearranged the crystal and capacitors to ensure no routing errors as on the previous PCB.
  • added a ground plane.
  • located all controlled circuit traces to top of PCB.
  • changed axial capacitor out for more cost effective equivalent capacitor with higher voltage rating (600v old component, 1000v new component).
  • Adjusted component layout to produce traces with fewer vias.
  • Adjusted holes in PCB for mounting purposes.
TinyTimer-KS PCB Design
TinyTimer-KS PCB Design

Bug Juice – found the error in the schematic

Prototyping is one of those things that when it works properly it can be irritating.  I found the bug in the circuit this evening.  I had the crystal oscillator and the capacitors in the wrong order.  Grr.  I’m going to salvage the prototype board, but it won’t be pretty.    Of course, the important part is that I found the mistake and didn’t make 100 copies of it.
That’s the joy and purpose of prototyping.  Here is my 6 component Hackduino running BLINK.  🙂

Barebones Arduino Test
Barebones Arduino Test

Tinytimer-KS Prototype Board first look

I’m excited to share that the prototype board has been assembled.  I did discover an issue with the run/program switch.  A few other minor adjustments were warranted as well.  Still working on getting the ISP to behave.  The assembled board looks good.  Here’s a picture:


I worked on this for several hours yesterday.  Realized I’m short some of the tactile switches and low on a few other components.  Ordered more pieces.  ISP would not work.  Kept getting 0x00 response from IDE.  Going to take another board and populate it with just the bare minimum pieces and see if it will work and then add to it from there.  There is a bug somewhere.  Only thing new is I’m using a different Arduino footprint from Sparkfun’s library.


Testing a transistor, relay, resistor combination to ensure long term success

I originally designed the tiny timer using an MJE3055 transistor.  I did this because I had one laying around.  Always a great excuse when hacking a project.  For production purposes, that’s not usually the best choice.  I decided that I would change over to one of my favorite transistors, the BC517.  It’s a high amplification transistor with an Hfe rating of 30,000.  This means that the signal amplification is 1:30,000.  The first time I put a timer together with it I promptly fried it.  That was unfortunate but a stark reminder to always check resistor values.  So today I setup the breadboard to do some component validation.  I wired a relay, BC517, and 1M ohm resistor.  I then coupled it to an Arduino Uno.  I don’t remember what sketch is on the Uno, but when I put a wire to pin 1 the relay started going off like a door bell.  Good enough for testing.  After an hour or two I’ll have accumulated enough cycles.  It’s running at around 4 cycles a second.  That yields 14,400 cycles an hour.  I’ll let it go for a couple of hours.  28,800 cycles is a good break in test.

For your amusement I’ve attached a short video I took with my Nexus 4 Android phone.

TinyTimer-Classic Prototype Boards arrived

Many thanks to our friends at OSHPark for another speedy order of prototype boards.  The boards arrived today for TinyTimer-Classic.  This is the ATTiny85 powered timer with a single AC or DC relay.  This revision adds a standard 6 pin ISP header and optimizes the component layout.  I will be documenting the build and verifying the code and components before launching the product on Tindie.  This product is geared towards hackers and makers.  It is customizable  via the Arduino IDE and supports most basic functions.

TinyTimer Classic Prototype board
TinyTimer Classic Prototype board

TinyTimer-KS boards arrive

I’m excited.  The TinyTimer boards showed up today from OSHPark.  Hope to have one assembled and get it into testing.  These are the latest prototype revision.

TinyTimer-Kickstarter Prototype
TinyTimer-Kickstarter Prototype

Net Hatchling – a ENC28J60 DIP Breakout board



I put a new project together this weekend.  It is called Net-Hatchling.  It’s a break-out board for the ENC28J60.  The ENC28J60 is a micro-chip ethernet controller.  It’s relatively inexpensive and available in a DIP format.  There are essentially two alternatives for ethernet in the Arduino world, this chip and a Wiznet5100.  Wiznet 5100 is only available in a SOIC format which is not hobbyist friendly.

The idea for net-hatchling is that it packages a power supply, the ethernet controller, and an ethernet jack.  I’m using USB for a power source again and then regulating it to 3.3v.  Fair warning the ENC28J60 is a 3.3v chip that is 5v tolerant.  This means you can talk to it with a 5v arduino, but you can’t listen to it without some level converters… unless you run the Arduino at 3.3v which is supported.

After I get the prototype boards in I will offer this as a kit via Tindie.  I want to make sure there aren’t any mistakes before I offer it for sale.  There are cheaper ways to get a ENC28J60 ethernet for arduino, but I’m not aware of any kits that use the DIP variant.

There are some libraries for this and so it should be a pretty easy off the shelf widget… and it’s alot cheaper then an ethernet shield.

Please let me know if this is something you find interesting.

Many thanks to Sparkfun for their Eagle Library.  I used their open-source part library and customized a version for the DIP package.

This design is based off of several published open source schematics and datasheet examples including the ENC28J60 datasheet from MicroChip. ENC28J60 Datasheet

Net Hatchling