Gas station without pumps

2012 July 24

EKG blinky

I ordered a printed circuit board from OSH Park, which has replaced DorkbotPDX that I blogged about a week ago.  The price is still just $5/square inch for 3 copies ($10/square inch for 4-layer boards), including shipping.  I submitted an Eagle .brd file tonight that I designed today.

OSH Park’s artistic rendering of the EKG blinky board. The battery clip (for 2 CR-2032 batteries) takes up most of the space and the batteries will be most of the weight. There will be 3 screw terminals on the upper left for attaching the EKG leads, and the blinking LED in the bottom right. I added a trimpot to the design so that gain could be adjusted as needed.

OSH Park’s artistic rendition of what the back of the board should look like. Soldering may be a bit tight, but not as bad as SMD parts.

The board is a version of my EKG circuit including an LED that should flash in time with the heartbeat (as well as providing header pins for attaching to an Arduino or oscilloscope.  I feel pretty pleased that I got the board down to about 2.4 square inches, so I’m getting 3 copies of the board for $12.15, especially as I used all through-hole parts and most of the space is taken up by the battery pack.

I’m not planning to have students solder up this board for the circuits class—there is no design task there, just technician-level skills.  I plan to design a somewhat larger board that allows prototyping instrumentation amp circuits similar to this EKG circuit, but which doesn’t have fixed wiring.  I’m still trying to decide whether to have resistors lying flat (as on this board), or mounted vertically from the board, as I usually do on a breadboard.  For this board, since the result is a wearable EKG, I wanted as much durability as I could easily get, but for the prototyping board, the ease of wiring resistors between holes 0.1″ apart may trump the extra robustness of laying them flat on the PC board.

7 Comments »

  1. […] designing and ordering the PC board for my EKG blinky circuit, I decided to try designing a prototyping board for students to design their own EKG (or […]

    Pingback by Instrumentation amp protoboard « Gas station without pumps — 2012 July 26 @ 17:49 | Reply

  2. […] ordered an EKG-blinky printed circuit board from OSH Park, on 2012 July 25, and it arrived today, 2012 Aug 13, a delivery time of 19 days, […]

    Pingback by EKG blinky boards arrived « Gas station without pumps — 2012 August 13 @ 22:20 | Reply

  3. […] EKG blinky […]

    Pingback by Order and topics for labs « Gas station without pumps — 2012 August 16 @ 23:39 | Reply

  4. […] EKG blinky The Arduino software was written by my son and works, but I think he is still doing some work on the Python programs for the laptop, and he hasn’t finished documenting them yet.  I can get nice plots like this from the EKG blinky using the command-line Python program he wrote and gnuplot, but the Python program that provides real-time plots on the screen is not able to maintain the 3msec sampling rate and drops data. Share:PrintEmailMoreTwitterDiggFacebookLinkedInPinterestStumbleUponRedditTumblrLike this:LikeBe the first to like this. Leave a Comment […]

    Pingback by EKG blinky boards work « Gas station without pumps — 2012 August 18 @ 11:52 | Reply

  5. […] they arrived by mail today 2012 August 18, a delivery time of 20 days, only one day longer than the EKG-blinky printed circuit boards from OSH Park, despite having to come from China.  Most of the delay was the airmail from […]

    Pingback by Instrumentation amp prototyping boards arrived « Gas station without pumps — 2012 August 18 @ 16:12 | Reply

  6. […] common-mode rejection, which is why I decided to use the INA126P instrumentation amp chip for the Blinky EKG boards and for the instrumentation amp […]

    Pingback by 2-op-amp instrumentation amp | Gas station without pumps — 2013 July 7 @ 20:50 | Reply

  7. Can I get a copy of your design files?

    Comment by Salman Sheikh — 2013 August 24 @ 17:11 | Reply


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