Apr 25, 2017 #1 S suman28pandit Newbie level 2 Joined Apr 25, 2017 Messages 2 Helped 0 Reputation 0 Reaction score 0 Trophy points 1 Activity points 15 I want to design a selectable input NAND gate using IC 7420 which should work as a 2- or 3-input NAND gate even when 2 or 3 inputs are applied
I want to design a selectable input NAND gate using IC 7420 which should work as a 2- or 3-input NAND gate even when 2 or 3 inputs are applied
Apr 25, 2017 #2 esp1 Advanced Member level 1 Joined Sep 4, 2007 Messages 402 Helped 139 Reputation 278 Reaction score 139 Trophy points 1,323 Location England Activity points 3,391 hi, Connect any unused inputs to a used input. E
Apr 25, 2017 #3 d123 Advanced Member level 5 Joined Jun 7, 2015 Messages 2,505 Helped 494 Reputation 992 Reaction score 525 Trophy points 1,393 Location Spain Activity points 27,148 Hi, ...or tie unused inputs to an appropriate logic level with a suitable value resistor.
Apr 25, 2017 #4 Altaero Member level 4 Joined Dec 30, 2013 Messages 78 Helped 24 Reputation 48 Reaction score 24 Trophy points 8 Location St-Petersburg, Russia Activity points 575 If I understand you right, you want to let some pins occasionally be unconnected? Just pull-up these pins. In case they are unconnected, they will have high level and the gate will act as 2- 3- input NAND (or NOT gate if you use 1- input).
If I understand you right, you want to let some pins occasionally be unconnected? Just pull-up these pins. In case they are unconnected, they will have high level and the gate will act as 2- 3- input NAND (or NOT gate if you use 1- input).
Apr 25, 2017 #5 S suman28pandit Newbie level 2 Joined Apr 25, 2017 Messages 2 Helped 0 Reputation 0 Reaction score 0 Trophy points 1 Activity points 15 d123 said: Hi, ...or tie unused inputs to an appropriate logic level with a suitable value resistor. Click to expand... I am unable to determine that logic level
d123 said: Hi, ...or tie unused inputs to an appropriate logic level with a suitable value resistor. Click to expand... I am unable to determine that logic level
Apr 25, 2017 #6 Audioguru Advanced Member level 7 Joined Jan 19, 2008 Messages 9,457 Helped 2,151 Reputation 4,302 Reaction score 2,008 Trophy points 1,393 Location Toronto area of Canada Activity points 59,721 An input on a NAND gate does nothing when it is at a logic high. Connect the unused input to the +5V supply to make it a logic high.
An input on a NAND gate does nothing when it is at a logic high. Connect the unused input to the +5V supply to make it a logic high.
Apr 25, 2017 #7 d123 Advanced Member level 5 Joined Jun 7, 2015 Messages 2,505 Helped 494 Reputation 992 Reaction score 525 Trophy points 1,393 Location Spain Activity points 27,148 Hi, A bit late, but still... 0 + 0 + 0 + 0 = 1 1 + 0 + 0 + 0 = 0 0 + 1 + 0 + 0 = 0 0 + 0 + 1 + 0 = 0 0 + 0 + 0 + 1 = 0 1 + 1 + 0 + 0 = 0 etc. NAND is only all 0s make a 1, any 1s make a 0.
Hi, A bit late, but still... 0 + 0 + 0 + 0 = 1 1 + 0 + 0 + 0 = 0 0 + 1 + 0 + 0 = 0 0 + 0 + 1 + 0 = 0 0 + 0 + 0 + 1 = 0 1 + 1 + 0 + 0 = 0 etc. NAND is only all 0s make a 1, any 1s make a 0.
Apr 25, 2017 #8 Altaero Member level 4 Joined Dec 30, 2013 Messages 78 Helped 24 Reputation 48 Reaction score 24 Trophy points 8 Location St-Petersburg, Russia Activity points 575 d123 said: Hi, A bit late, but still... 0 + 0 + 0 + 0 = 1 1 + 0 + 0 + 0 = 0 0 + 1 + 0 + 0 = 0 0 + 0 + 1 + 0 = 0 0 + 0 + 0 + 1 = 0 1 + 1 + 0 + 0 = 0 etc. NAND is only all 0s make a 1, any 1s make a 0. Click to expand... That is NOR, not NAND ;-) NOR is 0 if any of the inputs is 1. NAND is 0 if all of the inputs are 1.
d123 said: Hi, A bit late, but still... 0 + 0 + 0 + 0 = 1 1 + 0 + 0 + 0 = 0 0 + 1 + 0 + 0 = 0 0 + 0 + 1 + 0 = 0 0 + 0 + 0 + 1 = 0 1 + 1 + 0 + 0 = 0 etc. NAND is only all 0s make a 1, any 1s make a 0. Click to expand... That is NOR, not NAND ;-) NOR is 0 if any of the inputs is 1. NAND is 0 if all of the inputs are 1.
Apr 25, 2017 #9 d123 Advanced Member level 5 Joined Jun 7, 2015 Messages 2,505 Helped 494 Reputation 992 Reaction score 525 Trophy points 1,393 Location Spain Activity points 27,148 Altaero said: That is NOR, not NAND ;-) NOR is 0 if any of the inputs is 1. NAND is 0 if all of the inputs are 1. Click to expand... Oh dear, you're right, just as well you pointed it out, thanks.
Altaero said: That is NOR, not NAND ;-) NOR is 0 if any of the inputs is 1. NAND is 0 if all of the inputs are 1. Click to expand... Oh dear, you're right, just as well you pointed it out, thanks.