#garfield Logs

Feb 28 2023

09:01 AM aandrew: hm
09:12 AM aandrew: here's a nice diversion
09:12 AM aandrew: I'm measuring a rising edge on a board
09:12 AM aandrew: 10% to 90% (3.3V) in 2ns
09:12 AM aandrew: can I estimate the drive current of the driver?
09:12 AM aandrew: I know I=CdV/dT, so I/C=2.64V/2ns, so I = 1320000000*C
09:12 AM aandrew: and if I assume 5pF for the receiver capacitance and a few more pF for board capacitance I arrive at about 9-13mA of drive strength which seems to make sense
09:12 AM aandrew: but I'm using a 500MHz passive probe and that probe's got 8pF of capacitance all on its own
09:12 AM aandrew: so does that mean my current estimate should be even higher since it's also driving the probe load?
11:11 AM rue_mohr: the electricity is back!
11:11 AM rue_mohr: my generator ate the pull cord
11:11 AM rue_mohr: its about 5" of snow right now
08:33 PM rue_shop2: cold cold
08:37 PM Tom_L: light a fire
08:37 PM Tom_L: fix gen
08:59 PM rue_shop2: yea I have to pull that hub off with the ball snag in it
08:59 PM rue_shop2: where you have to lock the flywheel
09:00 PM rue_shop2: after taking off the front cowling
09:00 PM rue_shop2: and the pull thinger on the cowling isn't screwed in, its one of the ones with the bent tabs
09:10 PM Tom_L: i usually shove a screwdriver in the cooling fins
09:11 PM rue_shop2: tearing engines down, I'v broken more than a few fins off
09:11 PM rue_shop2: I wonder if I can 3d print that tool from a picture of it