Nuts & Volts - February 2006

Parts and Construction

See the Parts List for a detailed description of each part, where it can

be obtained, and how much it costs.

Most parts are available from Digi-Key ( www.digikey.com). Some others are available from RadioShack.

The LCD display is available from B and G Micro ( www.bgmicro.com) for $4.95, part #LCD1022. The temperature/humidity sensor is available from Onset Computer, Inc., for $19.17 each. Contact Onset by phone at 508-759-9500, mail at P.O. Box 3450, Pocasset, MA 02559- 3450, or email at sales@onsetcomp. com They also have a website at www.onset comp.com but the SHT15 is not available there. Figure 3 gives a view of the etched side of the PC board, while Figure 4 shows the component side of the board with an “x-ray” view (Figures 3 and 4 are available on the Nuts & Volts website at www.nuts volts.com). Figure 5 is a schematic of the monitor while Figure 6 is a schematic of the LCD backlight driver (EL driver).

The construction of the monitor PC board is quite simple, however the entire unit including the LCD backlight driver could easily be done on the RadioShack pre-drilled, solder-ringed holes, PC Board using point-to-point wiring. The LCD backlight driver should not be operated unless it is connected to the LCD. The voltages from the driver can easily exceed 600 volts with no load. When connected to the LCD, this voltage drops to about 100 volts.

INDOOR/OUTDOOR TEMPERTAURE

& RELATIVE HUMIDITY PARTS LIST

RESISTORS SUPPLIER PART NO. PRICE ❑ 4.7K Digi-Key 4.7KEBK-ND Pkg of 5 at $. 28 each ❑ 100K Digi-Key 100KEBK-ND Pkg of 5 at $. 28 each ❑ 1M Digi-Key 1MEBK-ND Pkg of 5 at $. 28 each ❑ 100K Digi-Key 100KEBK-ND Pkg of 5 at $. 28 each ❑ 330 Digi-Key 330EBK-ND Pkg of 5 at $. 28 each ❑ 1K Digi-Key 1KEBK-ND Pkg of 5 at $. 28 each ❑ 10K Digi-Key 10KEBK-ND Pkg of 5 at $. 28 each ❑ 25K ohm trimpot Digi-Key 3006P-253-ND $1.73

CAPACITORS

❑ 47 μF, Electrolytic Digi-Key 493-1039-ND

❑ 39 pf disc Digi-Key 1333PH-ND

SEMICONDUCTORS

❑ CD4011 Quad Two Input Digi-Key $. 50 NAND Gate ❑ 16F870 PIC Digi-Key $4.63

$. 24 Pkg of 10 $. 60

❑ MPF960 FET N-Channel or Equivalent ❑ 1N4001 Diode

MISCELLANEOUS
❑ Wire Jumper
❑ 2 Row, 16 Char/Row LCD,
4 Data Lines, Using HD (Hitachi)
44780 Controller or Equivalent,
EL Backlight optional For
connection/programming details,
click on "Technical Information"
at the website.
❑ Normally Open Momentary
Push Button Switch
❑ 14 Pin DIP Socket (for CD4011)
❑ 28 Pin DIP Socket (for 16F870)
❑ Plastic Project Box
❑ Single Sided Copper Clad PC
Board, 3"x 4"
❑ Battery Holder for 4 x AA cells
❑ 3.5mm (1/8") Mini Stereo
Jack 3 Conductor (Female)
❑ 3.5mm (1/8") Mini Stereo
Jack 3 Conductor (Male)
❑ 3.5mm (1/8") Mini Audio
Jack 2 Conductor (Female)
❑ 3.5mm (1/8") Mini Audio
Jack 2 Conductor (Male)
❑ PC Board (if used in lieu of
Copper Clad PC Board)
4-1/2" x 6-5/8"
❑ SH T15 Temperature/Humidity
Sensor