danuke

does anyone know of a 16 to 4 line encoder and part number? It can be either cmos or ttl. I've searched google and here and didn't come up with anything. If something exists like this please let me know.

All help is appreciated.

Thanks,
Joe

blueroomelectronics

Never seen such a chip. Wonder how would it handle more than one high input at a time?

__________________
Bill
Smart Kits build Smart People
http://www.blueroomelectronics.com

danuke

Not sure on the more than a single high part. Basically looking for something like a BCD encoder or a 10 to 4. I'm actually just looking at using 12 of the inputs, not all 16.

Pommie

Have a look at the 74148 - 8 to 3 priority encoder. If I remember correctly there is some way to cascade them.

Alternatively, it can be done with a diode array. Tie each output low and have a diode from each input to each output line that has to be high.

Mike.
Edit, google priority encoders.

nickelflippr

Harris HD0165

ericgibbs

hi,
Look at the HEF 4532 , 8 input priority encoder, you cascade two of these ic's to give a 16 bit encoder.

__________________
Eric
"Good enough is Perfect"

PIC tutorials:
Gramo's: www.digital-diy.net/
Bill's: www.blueroomelectronics.com/

on1aag

Hi Danuke,

Here's one, but that chip is almost as old as I am.

http://www.alldatasheet.com/datashee...LD/74C922.html

You gonna have to "visit" a museum to get one.

on1aag.

ericgibbs

hi on1aag,
You must visit my workshop [museum] , I have got about 4 or 5 on the shelf!

Actually they are 4*4 [x,y] scan matrix to a 4bit output with a strobe, used on keypads.

__________________
Eric
"Good enough is Perfect"

PIC tutorials:
Gramo's: www.digital-diy.net/
Bill's: www.blueroomelectronics.com/

Nigel Goodwin

That's what the 74C922 was, a keypad encoder.

Perhaps the OP might like to mention what he wants it for?.

__________________
PIC programmer software, and PIC Tutorials at:
http://www.winpicprog.co.uk

blueroomelectronics

I've seen the 74C922 on the University of Toronto PIC demo board. You can still get them but they cost more than a PIC 16F628A would (that could replace it, and offer more features too like key rollover and buffering) and enough I/O left over for a buzzer

__________________
Bill
Smart Kits build Smart People
http://www.blueroomelectronics.com

ericgibbs

hi Bill,
I would agree they are expensive, I wouldn't recommend them for a new design.
However, I have seen 2 or 3 members asking for information on the ic.

__________________
Eric
"Good enough is Perfect"

PIC tutorials:
Gramo's: www.digital-diy.net/
Bill's: www.blueroomelectronics.com/

Nigel Goodwin

I suspect it's mainly because they look in the old databooks, or google for keypad encoder, and this is what pops up.

__________________
PIC programmer software, and PIC Tutorials at:
http://www.winpicprog.co.uk

ericgibbs

The members asking the questions have also been in the 'developing' countries, I wonder if its the 'time shift' factor on obsolete components?

Actually, the 74C922 is/was an excellent device, its just the price thats counts it out, never had one fail!

There are lots of posts ref 741 opa, I expect the hedgerows of the world are littered with 'old' devices.

__________________
Eric
"Good enough is Perfect"

PIC tutorials:
Gramo's: www.digital-diy.net/
Bill's: www.blueroomelectronics.com/

Leftyretro

It reminds me of the robust business on E-bay for Nixie tube displays. Seems that many want to build digital clocks using these old displays even though it's really old tech and can take quite a few bucks gathering all the high voltage parts and such. I use to have tons of that old stuff around but somehow between home moves most is gone. Still have lots of mid 80s and on stuff.

Lefty

__________________
Measurement changes behavior

danuke

I'm using it to encode 12 pushbuttons into a 4 bit code. It's not for a keypad per say but something similar. It's just going to take the 12 pushbuttons and make it into a 4 bit binary value so that it can be used with less traces to be run, etc on a pcb.