The following are some Electronic Projects that I have built recently.
Most are based on PIC Microcontrollers. Thanks to Paul Kelly and Craig Studwicke and Terry McCreary's book for helping me get started
This makes for an easy connection from a load cell to a Dataq A/D system
Note the TIP29 power transistor. I used this to eliminate loading of the INA125P with the 10 volt load cell excitation. Power supply is a +- 15 Volt AC supply. I have AC Power at my current test stand location. For larger motors (at a remote location) I will use a +- 18 volt supply using four 9 volt batteries. No gain setting resistor is installed in this photo.
The above board is the INA125 amplifier that I am now using. I added a 120 volt AC bipolar 15 volt power supply with inputs to allow using four(4) 9 volt batteries in the field when 120 VAC is not available. The board includes on board voltage regulators and a +10 volt amplifier/buffer for the load cell excitation. The two pots allow for both gain and zero adjustments. The board also uses an LM301AN buffer amplifer for zeroing out the output if required. I have found that the bipolar 15 volt supply combined with using 10 volt load cell excitation allow for the best A/D resolution and best noise performance.
I took Craig's code and modified it adding a beeper to indicate "ready to launch" and also to beep pulses after the time cycle for location.
All of the above recovery devices have a seperate power supply for the electric matches. I use a single 9 volt NICAD. I can supply PC Board layouts in Gerber format for anyone interested in building any of the above. Email me at pbunn@matrixei.com