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 !
ALDL circuit
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Papatewks
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ALDL circuit
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In-Tech
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Re: ALDL circuit
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.
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.
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In-Tech
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Re: ALDL circuit
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
Doesn't need ethernet, this circuit is signal and ground...back in the day we had all kinds of RJ45 stuff laying around 
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
Doesn't need ethernet, this circuit is signal and ground...back in the day we had all kinds of RJ45 stuff laying around You do not have the required permissions to view the files attached to this post.
Last edited by In-Tech on Fri Dec 15, 2023 2:54 am, edited 1 time in total.
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Papatewks
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Re: ALDL circuit
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.
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In-Tech
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Re: ALDL circuit
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.
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In-Tech
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Re: ALDL circuit
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
Shoot, I probably could have gotten away with a 1488/1489 but I always overbuild stuff 
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
Shoot, I probably could have gotten away with a 1488/1489 but I always overbuild stuff
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MudDuck514
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Re: ALDL circuit
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
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