[NJARC] Richard Brewster rebuilds the Eccles-Jordan flip-flop

[Jim Whartenby]

AlexNot to be too picky but there is an obvious error in the Flip-Flop schematic.  The right hand relay shows no contacts.
Beyond this minor error, the Sensitive or Morris Relay seems to require somewhere around 40 to 60 mA to operate reliably but the 01A has a typical plate current of only 3 mA!  The 01A would be struggling in this circuit.
HB-3 data shows no maximum 01A ratings but shows curves out to about 10 mA with 158 volts on the plate and -5 volts on the grid.  With 100 volts on the plate and zero grid volts, plate current should be about 8 mA give or take.  With a hard +9 volts on the grid as per the schematic, we are in unknown territory.  I have no idea how reliable an 01A is under these conditions.  Perhaps this explains the resistor problems noted in the text?
Then there is the final issue of applying 6 volts to a 5 volt rated filament.
Even the 6J5 would have difficulty in this circuit.  Maximum plate current rating is 20 mA; typical plate current is 10 mA at 100 volts plate.  But to be fair, there are curves in HB-3 that show 40+ mA of plate current with +9 volts on the grid.  So there is hope in using the 6J5 in this circuit using the Morris Relay.Regards,Jim


      From: Alex Magoun <a.b.magoun at ieee.org>
 To: njarc at mailman.qth.net 
 Sent: Tuesday, May 29, 2018 3:47 PM
 Subject: [NJARC] Richard Brewster rebuilds the Eccles-Jordan flip-flop
   
Now online at IEEE Spectrum: https://spectrum.ieee.org/geek-life/hands-on/recreating-the-first-flipflop. Looking forward to the next show and tell for variations on this theme. . . . And the first comment suggests that engineering profs do have room for some history--on their own terms, to be sure:)
Alex
~~~
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IEEE History Center
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USA

+1 732-981-3414
a.b.magoun at ieee.org
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