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New Cosmac Elf Recreation on PCB


Rizal Acob
 

I just created an album showing 3pics of my latest Cosmac Elf system recreated on PCB. Thanks to Emilio Aoi for the PCB design. Please browse on the album if you have time.Thanks


 

Very very nice. Great looking build.

David


David Madole
 

Rizal,

 

That is very nice. I was just wondering a few days ago if someone had done a PCB for a classic ELF.

 

Are artwork or boards available?

 

David

 

 

From: cosmacelf@groups.io <cosmacelf@groups.io> On Behalf Of Rizal Acob
Sent: Monday, August 3, 2020 1:20 AM
To: cosmacelf@groups.io
Subject: [cosmacelf] New Cosmac Elf Recreation on PCB

 

I just created an album showing 3pics of my latest Cosmac Elf system recreated on PCB. Thanks to Emilio Aoi for the PCB design. Please browse on the album if you have time.Thanks


Lee Hart
 

Rizal Acob wrote:
I just created an album showing 3pics of my latest Cosmac Elf system
recreated on PCB. Thanks to Emilio Aoi for the PCB design. Please browse
on the album if you have time.
This is a beautiful example of the PE Elf. Very true to the original. :-)

How did you wire up the switches? Are they hand-wired to the header/connector above the MP/IN switches? Or are the PCB mounted to a second board below the main board?

Lee Hart

--
A designer knows he has achieved perfection not when there is
nothing left to add, but when there is nothing left to take away.
-- Antoine de Saint Exupery
--
Lee Hart, 814 8th Ave N, Sartell MN 56377, www.sunrise-ev.com


Rizal Acob
 
Edited

Hi Lee...thanks for the comments. Here is picture of my wiring harness at the back on the switches.

Furthermore, I would like to extend my thanks to Josh Bensadon and Lee Hart since this recreation is based mainly from Josh’s Original Schematic plus the TIL311 display circuit was from that of Lee’s ....referenced from their Cosmac Elf 40th Anniversary.

Since I don’t really own the gerber files, I can not share it for now. I was permitted to have the PCB fabricated since I was who initiated to have the PCB project made. All 5 PCBs are now comitted. Thanks!


Lee Hart
 

Rizal Acob wrote:
Hi Lee...thanks for the comments. Here is picture of my wiring harness
at the back on the switches.
Aha... hand wired, just like the original! :-)

One thought; you could make the PCB switch area with holes to mount the switches and wire them up. To assemble, cut off this part of the PCB. Use the center hole for each switch as a "pilot hole" to drill a piece of metal or blank PCB material, for the switch mounting. Then you could use a header and socket to transfer the signals from the switch PCB to the main PCB.

Or, the original RCA "Microtutor II" was basically the ELF on a PCB. Its switches mounted to the main board, on top. It also featured two expansion connectors (memory and I/O).

Furthermore, I would like to extend my thanks to Josh Bensadon and Lee
Hart since this recreation is based mainly from Josh’s Original
Schematic plus the TIL311 display circuit was from that of Lee’s
....referenced from their Cosmac Elf 40th Anniversary.
You are most welcome! The whole point of that project was to get people building again. I guess we succeeded. :-)

Lee Hart

--
A designer knows he has achieved perfection not when there is
nothing left to add, but when there is nothing left to take away.
-- Antoine de Saint Exupery
--
Lee Hart, 814 8th Ave N, Sartell MN 56377, www.sunrise-ev.com


 

It's beautiful.  May I ask if you're in a position to measure the amount of current being used, please?  


Rizal Acob
 

Here is my test 7.5v to 9v no change in current consumption


 

Rizal.  Thank you so much.  Gosh, those TIL311 displays really use a lot of power.

Cheerful regards, Mike


Ham Radio
 

I just looked at the data sheet of the TIL311 last night.  Quite a nice part for a 1972 design.  There is a blanking pin on the chip and I suspect that some clever code could be used to reduce the duty on cycle of the LEDs.  One would need to toggle an output pin connected to the TIL311 blanking pin at the appropriate rate to reduce the current whilst keeping the display from blinking.

I have just purchased 10 of these devices and need to test them for proper operation.



--
Regards,
Bernie Murphy


Stuart Remphrey
 

On Mon, Aug 31, 2020 at 06:50 AM, Ham Radio wrote:
TIL311
Hmm, did you find 10x TIL311 somewhere, at a reasonable price?!


cmdrcosmac
 

What with TIL311's and DM9368's being hard to get and expensive from sketchy
suppliers, has anyone seen this:

http://www.jakeselectronics.net/projects_4bitbinaryto7segmenthexadecimaldecoder.php

PIC 16F28A's are an active part at Digikey. They have thousands of 'em at $2.03
D-K can program them.

-Chuck


Ham Radio
 

I purchased 5 for $28.88 on eBay They are brand new. See my recent  post on testing these devices and their current draw.
--
Regards,
Bernie Murphy


David Madole
 

> What with TIL311's and DM9368's being hard to get and expensive from

> sketchy suppliers, has anyone seen this:

There’s all kinds of alternatives, but in anticipation of building a Micro/Elf and maybe some other “classic” machines, I bought 20 ”new” ones on eBay last week from a US seller with perfect feedback for about $4.40 a piece. Really not that bad compared to the cost and trouble of alternatives, especially for “classic” designs.

 

David

 


Lee Hart
 

cmdrcosmac wrote:
What with TIL311's and DM9368's being hard to get and expensive from sketchy
suppliers, has anyone seen this:

http://www.jakeselectronics.net/projects_4bitbinaryto7segmenthexadecimaldecoder.php

PIC 16F28A's are an active part at Digikey. They have thousands of 'em
at $2.03
Another vintage solution is the Motorola MC14495. It's a CMOS equivalent of the DM9368; so much lower power. It's a 16-pin DIP hexadecimal latch/decoder/driver for a standard 7-seg LED display.

I wonder if it would be possible to layout a tiny PCB that has male pin on the bottom to match the TI TIL311 or HP 5082-7340, an MC14495 on top, and a 7-seg LED display on top of that?

Lee Hart
--
A designer knows he has achieved perfection not when there is
nothing left to add, but when there is nothing left to take away.
-- Antoine de Saint Exupery
--
Lee Hart, 814 8th Ave N, Sartell MN 56377, www.sunrise-ev.com


Hank Riley
 

The 16F628A is a "very old" part.  Microchip is discouraging their sale with the high pricing.  Notice there is no price break with quantity; that is a clue.

There should be newer, better parts down nearer $1 in small quantities.
____________________________________________________________


On Tuesday, September 1, 2020, 02:00:00 PM EDT, cmdrcosmac  wrote:

PIC 16F28A's (sic) are an active part at Digikey. They have thousands of 'em at $2.03



Magnus Kesselmark
 

I did once buy a batch (10 pcs) of TIL311 från China (AliExpress) and did test them and they all worked perfectly.

Also I have a handful of 1802s from China (and another handful from reliable suppliers in Sweden and USA) The Chinese CPUs are still untested but I have an old project on my working table right now and have a good opportunity to try them out.

Once I even got some SID chips (MOS 6510) and they were all flawless.


The TIL311s are running low on AliX, but I still find a few priced $5 each. Serach for "hexadecimal displays".


/Magnus

Den 2020-09-01 kl. 19:59, skrev cmdrcosmac:
What with TIL311's and DM9368's being hard to get and expensive from sketchy
suppliers, has anyone seen this:

http://www.jakeselectronics.net/projects_4bitbinaryto7segmenthexadecimaldecoder.php

PIC 16F28A's are an active part at Digikey. They have thousands of 'em at $2.03
D-K can program them.

-Chuck



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megaslug1
 

 There are also some nice 4 digit I2C LEDs, if a pure look isn't needed, drive that with a cheap micro and you have your address bus display, with one small cheap micro and a 4 digit display.
 A 2x16 LCD would work too, display address, data, and all sorts of other things. And had LCDs been available inexpensively enough at the time, they would be a natural fit for the low power of the 1802.

                           --Randy