EEVblog Electronics Community Forum

General => Buy/Sell/Wanted => Topic started by: JohnG on October 14, 2021, 07:45:09 pm

Title: [US] Donner 3500 for parts, needs a good home
Post by: JohnG on October 14, 2021, 07:45:09 pm
I have the mainframe of a Donner 3500 "portable" analog computer. It is missing all the amplifier cards, which was unknown to me until I acquired it, and that makes it suitable for parts or decoration only, unless someone out there has some amps for it.

I would love to find a good home for it, or at least see it go to someone who can use it to repair or maintain another one. Please contact me if you have any interest. It will be free to the right person willing to pay for shipping (I estimate >15 kg).

http://computermuseum.informatik.uni-stuttgart.de/dev_en/dnr3500/dnr3500.html (http://computermuseum.informatik.uni-stuttgart.de/dev_en/dnr3500/dnr3500.html)

John
Title: Re: [US] Donner 3500 for parts, needs a good home
Post by: Tarloth on October 14, 2021, 11:59:45 pm
What a BEAUTY!!!! It's a pity that I live a continent away!
Title: Re: [US] Donner 3500 for parts, needs a good home
Post by: james_s on October 15, 2021, 12:55:10 am
I have no space for it and no use for it so I am not the right person, but that thing is super cool. I hope somebody can restore it to working condition.
Title: Re: [US] Donner 3500 for parts, needs a good home
Post by: JohnG on October 15, 2021, 01:32:36 pm
I got it from my brother-in-law, who was clearing out an estate. I had him send it to me, but had I known that all the amps were missing, I would have not bothered. The amp are essential to the integrators, and the whole point of analog computers is to solve differential equations with integrators. So, the chassis has the readouts, power supplies, user interface (that's all the knobs, lights, banana jacks, etc.), but without the amps there's not much to be done. I was pretty bummed when I opened it up to find them missing :(.

John
Title: Re: [US] Donner 3500 for parts, needs a good home
Post by: james_s on October 15, 2021, 10:04:02 pm
Well it seems like something that wouldn't be too hard to replicate in terms of function, is there documentation available showing how the amplifier modules worked? The chassis with the user controls is half the battle.
Title: Re: [US] Donner 3500 for parts, needs a good home
Post by: JohnG on October 18, 2021, 03:58:31 pm
Well it seems like something that wouldn't be too hard to replicate in terms of function, is there documentation available showing how the amplifier modules worked? The chassis with the user controls is half the battle.

I lump this statement in along with "it's just engineering". Doable, but it would be a lot of actual work. Not really high on my list, I'm more interested in other stuff. But, I do hope that someone is interested enough to take up my offer. I hate to scrap it.

John
Title: Re: [US] Donner 3500 for parts, needs a good home
Post by: james_s on October 18, 2021, 05:54:36 pm
There are different degrees of "just engineering". Complex hybrids, custom analog ICs, stuff like that are a big undertaking and difficult if not impossible to achieve. This sounds like it could be more or less an op-amp on a board. I haven't seen the schematic though so I don't know.