First step: Find the DAC datasheet. To do that, I really need to clean up my desk papers.
A little later, the EE student (Samad) is going to come by, and we will start working on gathering information on the voltage requirement / current draw of various system components. Cleaning my desk papers will be helpful for that as well.
He's here, we're starting to go through some of the power-related stuff stuff. Some notes:
- The PMT base is rated at 250 mW @ 12Vdc = 20.8 mA (quiescent power). Ray said he could pick up some more barrel connectors at Fouraker's, so that we could do a direct measurement with the paddles connected. We'll wait to try that measurement until he can do that.
- We directly measured the power consumption of the Wi-Fi board by powering it from the Keithley sourcemeter through J8 pin 3. It typically consumes at most about 300 mA at high data rates. It would be a good idea though to inflate this figure to (say) 500 mA in case the board uses more power when located farther from the base station (currently it is less than 3 feet away). A limit of 500 is appropriate also because the on-board voltage regulator U2 (which generates the +3.3V logic level) can handle at most 500 mA anyway.
- We spent a while looking for information on the voltages and currents drawn by the DE3 board (for the GPS app), but the provided docs are frustratingly ambiguous on this point. We think it is probably using at most just the +12V, +5V, and +3.3V lines from the external power supply, but we don't know the actual current draw on each. We could supply these three using the Agilent and Keithley supplies and measure them that way. However, we decided that rather than doing an experiment today to measure this, we would postpone it to Monday afternoon, when we will have more time to set it up.
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