Question on SN74142s
Dylan Distasio
I recently picked up 2 SN74142 ICs. I'm about to show my ignorance again, but can someone with some patience walk me through how I would use these in a nixie clock. I'm familiar with the 74141s but have to admit after reading the SN74142 datasheet I am not entirely sure how this one works. I am still a beginner at digital logic, and would appreciate any help with utlizing a combo of a decimal counter / 4-bit latch /decimal decoder/ nixie driver in one IC.
David Forbes
Dylan,
Lucky man! I've never seen one of those chips in person.
I have used the old CMOS more-or-less equivalent, the CD4033 (which
drives 7-segment LEDs) to make a clock. You will need to wire the latch
in transparent mode, as the latch function is not needed for a clock.
RCA published an app note in their 1974 data book that I built in 1976.
It worked. I'll see if my scanner will cooperate enough to scan the app
note.
--
David Forbes, Tucson AZ
Adam Jacobs
-Adam
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chuck richards
Lucky. I have been working with this stuff since
around 1990, and during that time have only ever found
a small bunch of (10) of those 74142 ics. They are
extremely rare, made of pure unobtainium!
They are the equivalent of a decade counter connected to
a 74141 and all in one 16-pin DIP package.
TTL cookbook page 93 describes it.
Some notes from last time I had mine fired up:
Counter clear pin 1 is very sensitive to noise.
If using a 2.2k pullup resistor, a .01 uf or a .1 uF
to gnd. keeps the full count going. Without the cap,
the count goes 0 1 2 3 4 5 0
Carry out pin 14 stays high for all counts except 8 and 9.
Carry is low for counts 8 and 9, and it returns high when
count 0 is reached.
74142 belongs in a glass case, temperature and humidity
controlled, low light, nitrogen atmosphere.
Chuck
>>>> Datasheet http://diogenes.iwt.uni-**bremen.de/vt/laser/nixie/**
>>>>
>SN74142.pdf<http://diogenes.iwt.uni-bremen.de/vt/laser/nixie/SN74142.
>pdf>
>>>> Best,
>>>> Dylan
>>>>
>>>>
>>> Dylan,
>>>
>>> Lucky man! I've never seen one of those chips in person.
>>>
>>> I have used the old CMOS more-or-less equivalent, the CD4033
>(which drives
>>> 7-segment LEDs) to make a clock. You will need to wire the latch
>in
>>> transparent mode, as the latch function is not needed for a clock.
>>>
>>> RCA published an app note in their 1974 data book that I built in
>1976. It
>>> worked. I'll see if my scanner will cooperate enough to scan the
>app note.
>>>
>>> --
>>> David Forbes, Tucson AZ
>>>
>>>
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>>>
>>>
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