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Homebrew Equipment A place to show, design and discuss the weird and wonderful electronic creations from the hands of individual members. |
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15th Jan 2019, 11:10 pm | #21 |
Octode
Join Date: Jun 2013
Location: Huddersfield, West Yorkshire, UK.
Posts: 1,795
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Re: Retro computer homebrew: Orton Karenbak-1 computer
Hi Karen... back to that "old" chestnut..to minimise solder fumes as you say as with pvc coating fumes.. I have a small Ex puter fan fixed to the bench blowing air across my face..sometimes I forget to switch it on.."age"
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Should get out more. Regards Wendy G8BZY |
16th Jan 2019, 12:40 am | #22 |
Rest in Peace
Join Date: Jul 2011
Location: Bridgnorth, Shropshire, UK.
Posts: 787
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Re: Retro computer homebrew: Orton Karenbak-1 computer
Hi Wendy,
My use of Nylese goes back some thirty-five years. I was an incorrigible youth back then Now I've got a growing list of ailments to remind me that I'm not indestructible. |
18th Jan 2019, 10:20 am | #23 |
Heptode
Join Date: Apr 2011
Location: Gosport, Hampshire, UK.
Posts: 606
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Re: Retro computer homebrew: Orton Karenbak-1 computer
OK, Ive got the wiring pen and spools and a suitable piece of single sided copper clad board. I might still get a Eurocard though - it'll save a lot of centre popping and drilling!
Then I'll have to sort through my boxes of IC's - that might take longer! John
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18th Jan 2019, 3:17 pm | #24 |
Rest in Peace
Join Date: Jul 2011
Location: Bridgnorth, Shropshire, UK.
Posts: 787
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Re: Retro computer homebrew: Orton Karenbak-1 computer
Blimey! Drilling copper clad board for twenty-five ICs sounds like hard work. I could never get the spacing even enough, resulting in my IC sockets refusing to seat
But don't listen to me. This is someone who wanted plain perf board so etched away the copper on some vero board! Last edited by Karen O; 18th Jan 2019 at 3:18 pm. Reason: missing word |
18th Jan 2019, 4:13 pm | #25 |
Octode
Join Date: Nov 2004
Location: Hebden Bridge, West Yorkshire, UK.
Posts: 1,885
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Re: Retro computer homebrew: Orton Karenbak-1 computer
If you don't mind the expense I can recommend these boards http://www.roadrunnerelectronics.com...Boards/Oktapad
The are very well made, have nice pads and stand up to heat well. I've tried cheaper ones but to get the enamel to melt you need the iron HOT and when prototyping I end up re-doing joints over and over ending in lifted pads. The reverse has a nice ground plane too. I can also recommend their wiring pens (and kits) the wiring pen has a metal nozzle (rather than the plastic one on the vero which I, of course, quickly melted!) The also do the combs but I didn't bother with them and went rat's nest as this was a "make it up as you go along" project...https://stardot.org.uk/forums/viewto...=15350#p210135 D |
18th Jan 2019, 4:28 pm | #26 |
Heptode
Join Date: Apr 2011
Location: Gosport, Hampshire, UK.
Posts: 606
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Re: Retro computer homebrew: Orton Karenbak-1 computer
Thanks for that! I've been through my TTL box and very few HC IC's. I've got plenty of LS though. They should be OK shouldn't they? Just a bit more power?
On the spreadsheet, the ones highlighted in red are the LS versions of the HC ones in the computer. I don't mind the drilling so much as centre popping all the drilling positions through 0.1" squared paper! One dodgy hit and it all goes wrong - you can't re do it! John
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18th Jan 2019, 4:35 pm | #27 | |
Heptode
Join Date: Apr 2011
Location: Gosport, Hampshire, UK.
Posts: 606
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Re: Retro computer homebrew: Orton Karenbak-1 computer
Quote:
John
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18th Jan 2019, 4:40 pm | #28 |
Octode
Join Date: Nov 2004
Location: Hebden Bridge, West Yorkshire, UK.
Posts: 1,885
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Re: Retro computer homebrew: Orton Karenbak-1 computer
I must be more cack-handed I found it always jumped off unless I got it soldered quickly!
I'll be interested to see how you get on. Do keep posting pics. I am playing with the idea of recreating one of these in an FPGA or CPLD but I suspect that will end up with all my other half started projects! D |
18th Jan 2019, 4:57 pm | #29 |
Heptode
Join Date: Apr 2011
Location: Gosport, Hampshire, UK.
Posts: 606
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Re: Retro computer homebrew: Orton Karenbak-1 computer
Somebody called Lawrence Wilkinson did that - emulated an IBM 360 in an FPGA. I met him at Bletchley Park about 10 years ago.
http://www.ljw.me.uk/ibm360/vhdl/ Well over my head!! John
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18th Jan 2019, 5:47 pm | #30 |
Heptode
Join Date: Apr 2011
Location: Gosport, Hampshire, UK.
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Re: Retro computer homebrew: Orton Karenbak-1 computer
Karen, I've spent all afternoon on this looking at components etc and what I have in my junk boxes.
1. I have most of the ICs but not HC family, only LS types. They should work OK do you think, at the expense of a bit more power? 2. I don't have 74LS4040 IC 7 and 17, and they don't seem to exist. 74HC4040 seems readily available so is it OK to mix them with 74LS ? I already have a nice project box in my "come in handy" pile. Looks like it finally has! Regards John
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18th Jan 2019, 5:51 pm | #31 |
Dekatron
Join Date: Jun 2015
Location: Biggin Hill, London, UK.
Posts: 5,215
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Re: Retro computer homebrew: Orton Karenbak-1 computer
I'll second the recomendation for the Roadrunner wiring pen. It's very useful for one-off projects like this.
As for drilling holes for an IC socket in copperclad board, I used an odd bit of stripboard as a drilling jig. At one time you could get a tool that consisted of a drill bit with a cylindrical cutter round it. It drilled the hole and then cut away the copper leaving a nice circular pad round the hole. No idea where you'd get one now. |
18th Jan 2019, 7:17 pm | #32 |
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Location: Bridgnorth, Shropshire, UK.
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Re: Retro computer homebrew: Orton Karenbak-1 computer
Hi John,
You can mix LS TTL and HCMOS but you have to add pull-up resistors wherever an LS output drives a HCMOS input. Bear in mind that some HCMOS gates are Schmitt triggers and are used for generating delays. |
18th Jan 2019, 7:43 pm | #33 |
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Re: Retro computer homebrew: Orton Karenbak-1 computer
I remember the IC pin number labels for the back too, mirror image of course.
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18th Jan 2019, 10:32 pm | #34 | |
Heptode
Join Date: Apr 2011
Location: Gosport, Hampshire, UK.
Posts: 606
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Re: Retro computer homebrew: Orton Karenbak-1 computer
Quote:
John
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19th Jan 2019, 5:41 pm | #35 |
Heptode
Join Date: Apr 2011
Location: Gosport, Hampshire, UK.
Posts: 606
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Re: Retro computer homebrew: Orton Karenbak-1 computer
The MODE control appears to be a 5 pole 4 way rotary switch. Is there such a thing?
I found a 6P4W on Farnell and it was £69!! I haven't been able to find one so far. John
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20th Jan 2019, 10:55 am | #36 |
Heptode
Join Date: Apr 2011
Location: Gosport, Hampshire, UK.
Posts: 606
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Re: Retro computer homebrew: Orton Karenbak-1 computer
Well, that switch has turned in to a bit of a show stopper. Can't seem to get one anywhere without spending a lot of money, which I don't want to do.
I was hoping to build it with bits from my junk boxes, and I do have most of it. If nothing else, I've been through all my logic IC's now! Back burner for now, till I see a suitable switch somewhere. John
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20th Jan 2019, 12:15 pm | #37 |
Octode
Join Date: Aug 2006
Location: Stoke-on-Trent, Staffordshire, UK.
Posts: 1,082
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Re: Retro computer homebrew: Orton Karenbak-1 computer
Rs and others used to make a stackable selector switch 1 long shaft and i seem to remember single pole 12 way wafers you just added as many wafers as poles required
have you looked at this Trev |
20th Jan 2019, 1:48 pm | #38 |
Dekatron
Join Date: Jun 2015
Location: Biggin Hill, London, UK.
Posts: 5,215
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Re: Retro computer homebrew: Orton Karenbak-1 computer
I remember those switches from RS. They were called 'Makaswitch' or some similar term and came in 2 sizes. The switch wafers had 12 fixed contacts and existed in single pole, 12 way, 2 pole 6 way, 3 pole 4 way and 4 pole 3 way I think. There were also screening plates, spacers, a mains-rated switch, etc.
But getting back to the problem. The switch here seems to select logic signals. I think it would not be too much work to replace it with a handful of TTL ICs (AND gates, effectively) and a single pole switch. |
21st Jan 2019, 9:08 am | #39 |
Heptode
Join Date: Apr 2011
Location: Gosport, Hampshire, UK.
Posts: 606
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Re: Retro computer homebrew: Orton Karenbak-1 computer
Hello Trevor, yes I had considered that and I remember the Makaswitch but they're more than I'm prepared to pay!
Tony, I think I'll be going along with your suggestion. I spent an hour looking at it yesterday and I think it could be done with three or four 74HC08 (Quad 2 input AND). I've got one, they're still quite cheap to buy and I have a 1P4W BBM rotary switch. In the meantime, I'll keep my eyes open for a switch! John
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GQRP Club 4704 - BVWS Member Last edited by wireless_john; 21st Jan 2019 at 9:27 am. |
21st Jan 2019, 6:57 pm | #40 |
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Re: Retro computer homebrew: Orton Karenbak-1 computer
What about two 3 pole 4 way swithces, you will have to turn them together, join them with levers and a link (only goes +/- 60 degrees should be OK) or put them front to front and wire one backwards. Big edge knob for turning.
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