UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - Retro computer homebrew: Orton Karenbak-1 computer

Karen O · 25th Jan 2019, 7:52 pm

Hi John,

10k pull-downs will work with HC/HCT logic but a bit of a no-no on LS gates. I forget what current emerges from a low LS input - 400uA...? You have to pull it down to at least 0.5V and that demands a low value resistor - around 1k if I've got my Iout(LOW) right.

25th Jan 2019, 7:52 pm	#48
Karen O Rest in Peace Join Date: Jul 2011 Location: Bridgnorth, Shropshire, UK. Posts: 787	Re: Retro computer homebrew: Orton Karenbak-1 computer Hi John, 10k pull-downs will work with HC/HCT logic but a bit of a no-no on LS gates. I forget what current emerges from a low LS input - 400uA...? You have to pull it down to at least 0.5V and that demands a low value resistor - around 1k if I've got my Iout(LOW) right.