Electronics > Projects, Designs, and Technical Stuff

Replace HC by HCT, and LS by HCT

<< < (3/3)

wraper:
I would just replace everything with HC and don't leave any LS at all. If there are things which have TTL outputs and cannot be replaced or are powered from 3.3V, I would use HCT inputs connected to those. As I said, HCT instead of HC should work just fine. HCT is a compromise to use CMOS technology but leave it backward compatible with TTL (LS).

luiHS:

--- Quote from: wraper on May 24, 2019, 02:57:29 pm ---I would just replace everything with HC and don't leave any LS at all. If there are things which have TTL outputs and cannot be replaced or are powered from 3.3V, I would use HCT inputs connected to those. As I said, HCT instead of HC should work just fine. HCT is a compromise to use CMOS technology but leave it backward compatible with TTL (LS).

--- End quote ---

 
Ok, thanks, I will try to replace all the LS and HC with HCT.

I will also try to replace the 7407 with the 74HC4050, I hope it works. The 4050 I use it a lot, and in this circuit only one buffer of the 7407 is used. Having to use a new reference takes away space in the feeders of the Pick and Place, so I try to reduce the number of references.

 

duak:
luiHS, the 74HC4050 should work fine in this circuit.  As others have said, the unused inputs of the 74HC4050 should be connected to GND.  Also, since the 74HC4050 is not open collector, R1 is not needed.

I see that a 74HC04 is also used on this board to generate RESET_Z80.  You could also use two inverters in series to perform the same function as the 74HC07.  If there are two free inverters in the existing part, you would not have to add a 74HC4050.

In fact, the circuit could probably changed slightly to use only one free inverter.

luiHS:

--- Quote from: duak on May 24, 2019, 05:17:03 pm ---luiHS, the 74HC4050 should work fine in this circuit.  As others have said, the unused inputs of the 74HC4050 should be connected to GND.  Also, since the 74HC4050 is not open collector, R1 is not needed.

I see that a 74HC04 is also used on this board to generate RESET_Z80.  You could also use two inverters in series to perform the same function as the 74HC07.  If there are two free inverters in the existing part, you would not have to add a 74HC4050.

In fact, the circuit could probably changed slightly to use only one free inverter.

--- End quote ---


Ok, thanks.
Unfortunately, the 6 gates of the 74HC04 are in use in the circuit, I have to use an additional chip for that single gate of the 7407. I prefer to use the 74HC4050, because it is a chip that I use a lot, and so I do not use more feeders of the Pick and Place.

Navigation

[0] Message Index

[*] Previous page

There was an error while thanking
Thanking...
Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod