MEP EP#246: Doing Something Magical

<h4><a href="https://macrofab.com/blog/mep-ep246-doing-something-magical/">MEP EP#246: Doing Something Magical</a><br></h4><h4>Parker</h4> <ul> <li><a href="https://phys.org/news/2020-10-physicists-circuit-limitless-power-graphene.amp" target="_blank" rel="noopener">Physicists build circuit that generates clean, limitless power from graphene</a> <ul> <li>University of Arkansas physicists </li> <li>Energy harvesting the thermal motion of graphene</li> <li>Without getting all quantum about it, it seems to work by configuring the graphene as one electrode (or both) of a capacitor. As the graphene flaps in the breeze (actually Brownian motion, I assume), the changing geometry will change the capacitance.</li> <li>The team's next objective is to determine if the DC current can be stored in a capacitor for later use</li> <li><a href="https://www.youtube.com/watch?v=wrleMqm3HiU" target="_blank" rel="noopener">Youtube video</a></li> </ul> </li> </ul> <h4>Stephen</h4> <ul> <li>New test equipment design - picking the right opamp <ul> <li>Current sensing with a bit of a twist</li> <li>Powered by +/-12V</li> <li>Need to read current on the +12 and the -12 along with a +9V rail</li> <li>Opamp needs to be capable of reading a voltage drop in an environment where the common mode voltage is at or near the opamp supply voltage</li> <li>Current sense amplifiers</li> <li>INA1x9 series amplifiers from TI <ul> <li>Supply and common mode range are independent of each other</li> <li>2.7v to 60v</li> </ul> </li> <li>Convert a voltage to a current then change the gain by selecting an appropriate load</li> </ul> </li> <li>Iphone 12 doesn’t come with a charger? <ul> <li>Are chargers necessary?</li> <li>Don't we have like 300 of them lying around?</li> <li>Apple states environmental reasons for dropping the charger</li> <li>Also no earbuds</li> <li>Examples of other products that lack the equipment necessary to function <ul> <li>Video game consoles?</li> <li>Appliances?<