Printed Circuit Board for the 1-Wire Barometer

If you want to construct your own PC board download this package. The printed wiring is in the file Barobottom.bmp. This file's image is 905 x 631 pixels with a print resolution of 300 pixels/inch. Thus when printed it will yield an image of 3.017 x 2.103 inches in size. Your viewer/printer must print the image at this size. To be sure you have the correct size check the pads for the MPX4155. They should be spaced exactly 0.1 inches apart.

If you will be using Simon's Hub and its power see Modifications for Simon's Hub Power. If you are not going to use hub power you might want to cut the printed wires from the 5V power that goes to the modular socket. Check this out.

The diagrams which follow are not to scale and thus are not suitable for making the PC board. The top of the board diagram relates the parts values to their position for easy installation.

Top of board - not to scale

Bottom of board -- not to scale.

Notes on Barometer PC Board:

1. TP is a test point which has the voltage set by R5 (called Test Voltage Pot on main page). Make this test point with a short piece of wire.
2. Use short pieces of wire for the pins located below the test point.
3. Put a jumper in the "TEST" position to inject voltage set by R5.
4. Put the jumper in the "RUN" position to use transducer.
5. U2 (DS2438) is mounted on the bottom of the board, pin 1 is indicated.
6. I have tried to make the pads large enough for hobbyists to make this board.
7. The image should be suitable for "Iron On" transfers if you want to make the board yourself using that technique. I plan to send the layout to Far Circuits later.

Below is the parts list. I have given a Mouse part number for information only, use your own source.
www.mouser.com or, (800) 346-6873 or, sales@mouser.com

Parts:

• Modular Connector, 2 gang, each with 6 positions and 4 contacts, Mouser #154-6412, or
  Modular Connector, 2 gang, each with 6 positions and 6 contacts, Mouser #154-6612 if this is to be used with Hub power. Drilling 4 more holes required to install it.
• Power Connector, 2.1 mm pin, Mouser #163-5004
• U1 -- LM358, Radio Shack, Mouser, www.newark.com
• U2 -- DS2438, Dallas Semiconductor, Newark Electronics

• Pressure transducer:
  Motorola MPX4115A -- no port
  Motorola MPX4115AS -- side port
  www.phanderson.com, Newark
  Note: Motorola MPX4115AP might not fit on the board.

• Q1 -- 78L05, 5 volt regulator, TO-92 case, Mouser #628-80750AN

• D1 -- 1N5817 or equivalent, Mouser, Newark

• Potentiometers:
  • R3, R5 -- 10k pot, Bourns 3292 type, Mouser #72-T93YA-10k
  • R4 -- 5k pot, Bourns 3292 type, Mouser #72-T93YA-5k

• 1/4 watt Resistors:
  • R1 -- 47k
  • R2 -- 100k
  • R6 -- 15k
  • R7, R9, R10 -- 3.3k
  • R8 -- 2.2k
  • R11 -- 10k

• Capacitors:
  • C1 -- 4.7 MFD tantalum, 16 volt
  • C2 -- 2.2 MFD electrolytic, 25 volt
  • C3 -- 1 MFD tantalum, 16 volt

Jim Jennings, w5eut@earthlink.net
October 25, 2001

Modifications for Simon's Hub Power

1. Install Modular Connector, 2 gang, each with 6 positions and 6 contacts, Mouser #154-6612 -- instead of the 2 gang 6 position 4 contacts connector.
2. Do not install the LM78L05, the 2.1 mm DC connector, and 2.2 uf capacitor

Barometer Page