[vcf-midatlantic] A little electronics hack

Evan Koblentz evan at vcfed.org
Mon Sep 30 12:57:38 EDT 2019


>> Looks like someone on this list has already done the legwork on this as
of 2016... https://www.glitchwrks.com/2016/09/12/lego-logo-interface
<https://www.glitchwrks.com/2016/09/12/lego-logo-interface>

No - that's the card for connecting the computer to the interface box. That
schematic already existed and we didn't have the card, so Jonathan (Glitch)
built one for us. That is what you see documented. In the current thread I
am referring to the interface box itself. There is more info on my personal
website at http://www.mindsbeforethestorm.com/8bit_hardware.php.



On Mon, Sep 30, 2019, 11:16 AM Mark Whittington <markwhi at gmail.com> wrote:

> Looks like someone on this list has already done the legwork on this as of
> 2016...
>
> https://www.glitchwrks.com/2016/09/12/lego-logo-interface
>
> On Mon, Sep 30, 2019 at 9:13 AM Evan Koblentz via vcf-midatlantic <
> vcf-midatlantic at lists.vcfed.org> wrote:
>
>> >> If you're interested in investigating further if you point us to
>> schematics we can give suggestions.
>>
>> I am giving the box to Neville in early November (don't want to risk it
>> not
>> working before the Brickfair NJ event the first weekend of that month). He
>> agreed to my request to make a schematic of it.
>>
>> The next step will be to have someone else take his schematic, build one,
>> and send it back to me for testing. That'll prove that the box can in fact
>> be built from just the plans. After that I'll post it on my website.
>>
>> A possible third stage would be to make modern improvements, if any ideas
>> stand out.
>>
>> I'm only interested in the function, not in replicating the physical case.
>> But what I would avoid is replacing the vintage computer with a
>> microcontroller. I'm all for a better interface but strictly against some
>> non-vintage computer experience.
>>
>>
>>
>>
>> On Mon, Sep 30, 2019, 8:43 AM David Gesswein via vcf-midatlantic <
>> vcf-midatlantic at lists.vcfed.org> wrote:
>>
>> > > >> It's called a 'crowbar' circuit.  Prevents things from burning up.
>> > >
>> >
>> > What I normally called a crowbar circuit is the overvoltage protection
>> > where it intentionally shorts the output of the power supply. This
>> sounds
>> > more like over current protection.
>> >
>> > > What are common reasons why those stop working? Neville and I didn't
>> see
>> > > any obvious signs of damage to it.
>> > >
>> > Either component value shift or failed component. You indicated that it
>> is
>> > driving the motors better than it ever has. It may also be your motors
>> > are a heavier load than it was intended to drive.
>> >
>> > If you're interested in investigating further if you point us to
>> schematics
>> > we can give suggestions.
>> >
>> >
>> > > On Sun, Sep 29, 2019, 1:56 PM Mike Loewen <
>> mloewen at cpumagic.scol.pa.us>
>> > > wrote:
>> > >
>> > > > On Sun, 29 Sep 2019, Evan Koblentz via vcf-midatlantic wrote:
>> > > >
>> > > > > Neville noticed something that I wouldn't have. The circuitry
>> > contains a
>> > > > > safety mechanism to shut off all power if the current jumps too
>> high,
>> > > > such
>> > > > > as a kid inserting a paper clip. There's probably a technical name
>> > for
>> > > > that
>> > > > > but I do not know it. Anyway, for unknown reasons this circuit was
>> > > > kicking
>> > > > > in! He jumped it with an equal-length wire. :)
>> > > >
>> > > >     It's called a 'crowbar' circuit.  Prevents things from burning
>> up.
>> > > >
>> > > >
>> > > > Mike Loewen                             mloewen at cpumagic.scol.pa.us
>> > > > Old Technology
>> > http://q7.neurotica.com/Oldtech/
>> > > >
>> >
>>
>


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