Big squiggly area in the center of the second (bottom) image. On Mon, Sep 30, 2019, 1:48 PM Mark Whittington <markwhi@gmail.com> wrote:
https://4.bp.blogspot.com/-DGOlTkGXj_Q/U8-T2uBG5iI/AAAAAAAAATY/7ra6gVkSKg8/s...
https://4.bp.blogspot.com/-6RLSsFHgMgY/U8-TzfBRxOI/AAAAAAAAATQ/NeiKlqHPevs/s...
Out of curiosity (and assuming I've found the right board images), do you happen to know where the circuit that Neville identified as faulty is on these images? Also, I've found a couple of these units for sale in the US for ~$85 and in the UK for ~$50 that might be useful for backup or reverse engineering purposes.
Cheers,
-Mark
On Mon, Sep 30, 2019 at 12:57 PM Evan Koblentz <evan@vcfed.org> 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 <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@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@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@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@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@cpumagic.scol.pa.us > Old Technology http://q7.neurotica.com/Oldtech/ >