Powering up puzzle
#17
0.2 V forward drop? Wanders off to google... ah schotty 0.2 to 0.4 V, rather lower than I thought, my bad.

Only really need the series diode in the +3.3 V feed to the S1 jumper block that powers the E-field preamp. That is where a mis-jumpering or tweezer slip is going cause the +5 V and +3.3 V rails to come together. If some one chooses to power a board just resting on a work bench along with nuts/bolts and wire off cuts that's their probelm. B-)

The Blue E-field pre-amp uses the ADA4891 op-amp, minimum supply of 2.7 V, a silicon diode would drop to much. Higher end schotty would bring the supply at the controller board down to 2.9 V. Assuming 10 mA pre-amp load, 100 m of coax will only drop 0.025 V, so plenty of head room. Assuming the pre-amp design will still perform properly with a supply below 2.9 V.
Cheers
Dave.

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Messages In This Thread
Powering up puzzle - by MonkeeRench - 2017-06-12, 21:15
RE: Powering up puzzle - by kevinmcc - 2017-06-12, 23:03
RE: Powering up puzzle - by MonkeeRench - 2017-06-13, 15:51
RE: Powering up puzzle - by kevinmcc - 2017-06-14, 00:13
RE: Powering up puzzle - by MonkeeRench - 2017-06-14, 02:15
RE: Powering up puzzle - by kevinmcc - 2017-06-14, 05:03
RE: Powering up puzzle - by DelandeC - 2017-06-14, 08:42
RE: Powering up puzzle - by allsorts - 2017-06-14, 10:03
RE: Powering up puzzle - by kevinmcc - 2017-06-14, 23:12
RE: Powering up puzzle - by BobW - 2017-06-15, 04:11
RE: Powering up puzzle - by cutty - 2017-06-15, 05:38
RE: Powering up puzzle - by allsorts - 2017-06-15, 16:20
RE: Powering up puzzle - by kevinmcc - 2017-06-16, 22:57
RE: Powering up puzzle - by BobW - 2017-06-15, 12:05
RE: Powering up puzzle - by allsorts - 2017-06-15, 18:18
RE: Powering up puzzle - by Jon Point - 2017-06-16, 01:11
RE: Powering up puzzle - by allsorts - 2017-06-17, 22:39

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