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'[BUY]: RTL logic circuts MC 660 and MC 672'
2001\02\19@142521 by MEDICINTEKNIK KB

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In the early 70's RTL logic circuits preceded TTL. I am about to repair some old X-ray equipment fom that era, and need mentioned IC's for the purpose.

I have been unable to locate these in ordinary ways. If you collect stuff the way I do, you might have some....

Near Sweden preferred, but I pay cash in most currencies.

Sven in Sweden

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2001\02\19@145052 by Dan Michaels

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Sven in Sweden wrote:
>In the early 70's RTL logic circuits preceded TTL. I am about to repair
some old X-ray equipment fom that era, and need mentioned IC's for the purpose.
>
>I have been unable to locate these in ordinary ways. If you collect stuff
the way I do, you might have some....
>


Sven, if worst comes to worst, and you still must fix this equipment,
you may be able to get by with cutting out the chips and soldering on
some discrete NPN inverter circuits. That is really all RTL was.
Somewhere I have an old textbook showing nominal resistor values.

- dan

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2001\02\19@154355 by Chris Eddy

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Milton;

I have been working on some modernization efforts for the nuclear industry.  They have a number of designs which used this old logic.  The logic, if I
recognize the numbers, are MHTL logic, which is a high threshold logic version of DTL logic made by Motorola.  I would be wary of Dan's suggestion for
replacing with transistor logic, Dan assumed RTL, and in reality they are a bit more than that.  He meant well.  The best bet is to use a comparator around
7.5V (this is fixed regardless of supply) and then deal with the logic levels.  Outputs are either an active transistor output in a peculiar buffer
arrangement, or a passive pullup with active pulldown.   Not a clip out solder in solution.  I know that the nuclear industry went absolutely to the end of
the earth to find these parts, which have been out of production for probably 25 years.

Wish the news was better.  Sorry.
Chris~

MILTON MEDICINTEKNIK KB wrote:

> In the early 70's RTL logic circuits preceded TTL. I am about to repair some old X-ray equipment fom that era, and need mentioned IC's for the purpose.

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2001\02\19@172740 by Spehro Pefhany

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At 08:14 PM 2/19/01 +0100, you wrote:
>In the early 70's RTL logic circuits preceded TTL. I am about to repair
some old X-ray equipment fom that era, and need mentioned IC's for the
purpose.

If you want enough $$$+ worth to make it worthwhile for them, just contact
a gray
market dealer, there are still plenty of these old chips floating around.
Be sure
to specify the suffix (L or P).

Best regards,

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2001\02\19@223646 by Dan Michaels

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Chris Eddy wrote:
>Milton;
>
>I have been working on some modernization efforts for the nuclear industry.
They have a number of designs which used this old logic.  The logic, if I
>recognize the numbers, are MHTL logic, which is a high threshold logic
version of DTL logic made by Motorola.  I would be wary of Dan's suggestion for
>replacing with transistor logic, Dan assumed RTL, and in reality they are a
bit more than that.  He meant well.  The best bet is to use a comparator around
>7.5V (this is fixed regardless of supply) and then deal with the logic
levels.  Outputs are either an active transistor output in a peculiar buffer
>arrangement, or a passive pullup with active pulldown.   Not a clip out
solder in solution.


According to the textbooks [if one can believe them], "all" of the
old RTL, DTL, and HTL gates are fairly straightforward NPN circuits.

So, if unable to find these gates/chips anywhere, and if fixing
the equipment as opposed to trashing it is the major consideration,
then it would seem that clip out solder in may be the only possible
course of action. It cannot be all that difficult to try, assuming
only one or a few gates are blown - either works or doesn't work.

Unsolder the old chips, solder wirewrap headers into the holes, build
a new gate on fiber board [kind with plated-thru holes], and solder to
the WW legs.

[of course, this thing probably wouldn't meet FDA approval].

- dan

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2001\02\19@224029 by Sean Breheny

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Hmmm, so this is what will be running our nuclear power plants? <VBEG>

Sean


On Mon, 19 Feb 2001, Dan Michaels wrote:
{Quote hidden}

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2001\02\20@004842 by Dan Michaels

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At 10:40 PM 2/19/01 -0500, you wrote:
>Hmmm, so this is what will be running our nuclear power plants? <VBEG>
>
>Sean


No, this is what "has been" running our nuclear plants.

[probably also the air traffic controls, IRS, B-52 bombers,
10,000 nuclear tipped missiles, most of the navy, and the SAC
computers under Cheyenne Mtn - and if not here, then certainly
in several other countries].

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2001\02\20@011102 by shb7

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Hi Dan,

I wasn't clear. What I meant by "this" was little
hacked discrete replacements for old ICs. IIRC, someone
said that he was upgrading nuclear power plant
electronics and had to deal with these old ICs by
replacing them with equivalent circuits.

Sean

Quoting Dan Michaels <spamBeGonedanspamBeGonespamORICOMTECH.COM>:

> At 10:40 PM 2/19/01 -0500, you wrote:
> >Hmmm, so this is what will be running our nuclear
power plants? <VBEG>
> >
> >Sean
>
>
> No, this is what "has been" running our nuclear
plants.
>
> [probably also the air traffic controls, IRS, B-52
bombers,
> 10,000 nuclear tipped missiles, most of the navy, and
the SAC
> computers under Cheyenne Mtn - and if not here, then
certainly
> in several other countries].
>
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>
>

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2001\02\20@012406 by Lee Jones

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>>> Hmmm, so this is what will be running our nuclear
>>> power plants? <VBEG>

>> No, this is what "has been" running our nuclear plants.
>>
>> [probably also the air traffic controls, IRS, B-52 bombers,

> I wasn't clear. What I meant by "this" was little
> hacked discrete replacements for old ICs. IIRC, someone
> said that he was upgrading nuclear power plant
> electronics and had to deal with these old ICs by
> replacing them with equivalent circuits.

No.  Original poster was asking for replacements for RTL
to repair X-ray machines.

Second poster said to swap discrete transistors for RTL.

Third poster said he'd been working with the nuclear industry
on RTL and other old logic families and warned _against_ using
discretes as replacement parts.  He said the nuclear industry
has bought up all the old replacement parts to keep their own
equipment running with the proper replacements.

                                               Lee Jones

P.S. Last I heard, air traffic control system was still
    on IBM 9020s, circa IBM 360 level of technology.

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2001\02\20@021651 by Sean H. Breheny

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Sorry, you're right, I looked at the messages again. I stand corrected.

Sean

At 10:25 PM 2/19/01 -0800, you wrote:
{Quote hidden}

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'[BUY]: RTL logic circuts MC 660 and MC 672'
2001\03\01@184545 by rottosen
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Sven:

I know that you wanted someplace closer than the US but...

Rochester Electronics( http://www.rocelec.com/ ) specializes in parts
like this. They even buy old masks to keep producing some popular (but
old) parts.

I did a search on their site and found the MC660L for about $11 US. They
do not show a MC672.

-- Rich


MILTON MEDICINTEKNIK KB wrote:
{Quote hidden}

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