really old magazine article on diy modem

Nov 14, 2006 7 Replies

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Brad 19 years ago

Hi all, I'm trying to find an article I read about 30 years ago or so. It was a diy project for a low speed modem. It was in Byte, Kilobaud or Popular Electronics. Do any of you happen to know where this article might have been?

If I recall, the modem was like 300 baud or maybe only 110. I'm doing a little project that could use a dirt cheap modem, and signalling speed is not an issue. Slow is fine, cheap is better :)

Or, if anyone has a more up to date approach I'd be glad to look at that too. I've come across a few half-way described implementations of modems using PICs, but I don't have the time to figure out the missing details.

Regards, Brad

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Homer J Simpson 19 years ago

IIRC it was Popular Electronics and it was an acoustic coupler.

Look on eBay for an old Radio Shack modem.

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Tom Bruhns 19 years ago

Google "modem IC" and you'll get quite a few hits. Search for "Bell

103 modem IC" and you'll get things more targeting what you are asking for. There are other ways to phrase the search that will become obvious from the hits you get on those. I suppose some of the slow modem ICs are still available. MM74HC943 seems to not be made by National now, but perhaps someone has stock.

Cheers, Tom

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Ross Herbert 19 years ago

If cheap is what you want there will be literally thousands of unused dial-up modems lying around which can be had for a few dollars if not for free. These are tried and proven so you won't have to spend time developing and proving a design either... why re-invent the wheel?

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Jeff Findley 19 years ago

I've found old RS-232 modems (often 9600 baud and higher) at places like Goodwill, garage sales, and etc. for $5 or so. You might even try eBay. You can get just about anything on eBay.

Jeff

"They that can give up essential liberty to obtain a little temporary safety deserve neither liberty nor safety" - B. Franklin, Bartlett\'s Familiar Quotations (1919)

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GregS 19 years ago

36 years ago I was troubleshooting modems made from 7400 series chips. I didn't really know how the whole thing worked but I could fix bad logic. That was at DEC.

greg

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Michael Black 19 years ago

You're paying too much. I paid five dollars for my used 2400 baud external modem back in 1995.

I paid ten dollars for an external 33.6K modem some years back. And I got my 56K external modem for five dollars last year.

MIchael

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Michael A. Terrell 19 years ago

Find a large library with old magazines on microfilm, and start looking. There were dozens of those articles, and most used now obsolete ICs. There is a company in Ann Arbor, Michigan that made those microfilms. I think it was connected to the university. They used to advertise in '70s and '80s magazines.

Service to my country? Been there, Done that, and I\'ve got my DD214 to prove it. Member of DAV #85. Michael A. Terrell Central Florida

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