ALDL circuit

160 And 8192 Baud Aldl
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Papatewks
Posts: 10
Joined: Sat Oct 14, 2023 8:39 pm
cars: 1965 corvair

ALDL circuit

Post by Papatewks »

ALDL.jpg
When I started working with ALDL a few months ago, I burned a lot of google time looking for a good circuit for the electrical integration of ALDL. I'd like to share the best one I've found. I think it offers some advantages over rivals. In my implementation, R1 is actually internal to the raspberry pi I'm integrating with, so just have a 14 pin dip and one resister for the whole thing! And there's the option of supporting 2 (or 3) interfaces just by adding another 1 (or 2) resisters.
If you need an inverting interface, use a 7405 instead of 7407.
Enjoy !
In-Tech
Posts: 788
Joined: Mon Mar 09, 2020 4:35 pm
Location: California

Re: ALDL circuit

Post by In-Tech »

Hiya,
it might take me a while to find my old max233/7407 circuit if I even have it still from the early 90's, was straight db25 or db9 serial back in the day. It worked flawlessly on any baud rate, 160, 8192, everything I could test up to 500k. From memory, the 7407 is also an invertor(sp?). I think I still have a few hundred left if anyone wants some dips.
In-Tech
Posts: 788
Joined: Mon Mar 09, 2020 4:35 pm
Location: California

Re: ALDL circuit

Post by In-Tech »

Hiya,
Took me a bit to find my 50 ft cable I use in the boats with a Mefi puter. Yepper, ps2 powered, ethernet out, etc, etc :afro: Doesn't need ethernet, this circuit is signal and ground...back in the day we had all kinds of RJ45 stuff laying around :thumbup:
Max233.jpg
Last edited by In-Tech on Fri Dec 15, 2023 12:54 pm, edited 1 time in total.
Papatewks
Posts: 10
Joined: Sat Oct 14, 2023 8:39 pm
cars: 1965 corvair

Re: ALDL circuit

Post by Papatewks »

In-tech - I don’t know what you’re showing! A boat with ALDL? Do tell!! If you have some 7407’s laying around let me know, I’ll take them off your hands… 7407 is non-inverting. 7405 is same deal but inverting.
In-Tech
Posts: 788
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Location: California

Re: ALDL circuit

Post by In-Tech »

I have a few hundred left, I'll take pics in the next few days. They are at my shop still in the factory tubes and factory pink plastic.
In-Tech
Posts: 788
Joined: Mon Mar 09, 2020 4:35 pm
Location: California

Re: ALDL circuit

Post by In-Tech »

Hiya's,
Mercury Marine used to use the Mefi1,2,3 and Volvo/Penta used them as well as the Mefi 4's. All delphi's and 8192 baud. Anyhoosit, I thought I remembered those 7407's being an invertor, too long ago :wall: Shoot, I probably could have gotten away with a 1488/1489 but I always overbuild stuff :shh: :thumbup:
dm7407.pdf
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MudDuck514
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Re: ALDL circuit

Post by MudDuck514 »

Hi all,
FYI good design practice is to pull all unused inputs of the IC to ground, so the output circuit of each buffer stays at ground level, too. (Inverters would be tied HIGH using pull-up resistors like in the diagram)

Mike
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