Analog to Digital Converters You Can Build

While these devices were designed to be used with Data Collect Lite software and Radio-SkyPipe (Max187 only), there is no reason why you could not write your own program in BASIC to run them.  Below is the preferred, 12 bit version which uses a $14 MAX187 chip.

Construction of either circuit can be done on a small IC breadboard available from Radio Shack.  The power source should be well filtered or a battery. One neat way to package the units is inside a two way parallel port manual switch box. These can be bought for about $10 at computer shows. One of the DB25 connectors is removed from the back of the switch and replaced with a power and a analog input jack. Leads 2, 3, 12, 24, and 25 from the removed DB25 are soldered directly to the appropriate places on the AtoD board.  The switch can then be used to pass through to the printer when the AtoD is not in use.

The chips and voltage regulators can be purchased from DIGIKEY. I have been very happy with their mail order service.

Click here for an idea on constructing this ADC in a printer switch box.

Click here for the Maxim Integrated Circuits Application Note on interfacing to the serial port.

Click here view the schematic for the 8 bit version using the TLC548 IC.