Dear friends,
for those who are interested, I have drawn a very compact SMD version (total or hybrid) of the good 2519 Replacement described here:
https://oshwlab.com/szillat/2519-fixed
(I think the designer is a member here, if so: great job!)
The prototype I made works perfectly.
You can find the Gerber files here:
Enjoy,
Claudio
The DIP version is from me, please note that the idea was to use IC-sockets with integrated hidden cap.
Hi Guys -
I appreciate your efforts creating stuff for our beloved Apple-1 but from the point where I am standing I fail to see why such a substitution is necessary ?
Such little rider cards typically are made to replace an IC which can't be obtained anymore.
But the last time I bought Signetics 2519 (a few months ago) my chip broker told be there are still more than 5000 (IIRC) in stock at the same chip broker he gets them from. The problem is not getting them. They are there, sitting in the warehouse of that UK guy hoarding all these Signetics ICs.
The problem is to get them at a good price. If you buy 50 (2 tubes) you still can get them for $18 a piece.
If you buy them at Unicorn the price is twice that but this is a real business who can't give them away at their own cost, they have to add their margin, to pay for their overhead, and to make a living, and so their price is twice what they have to pay for them, which still is not usurious, but usual in this type of business. Otherwise, such small businesses can't exist.
How much does it cost to procure these PCBs and all the other parts and how much time to put it together ? Can you really save something ? How much is one of your hours of RQLT worth which you did put into this project ? 50 cents ? A quarter ? A dime ?
So please tell us what is the motivation for making such a PCB. In my eyes it does not make any sense to do so. But maybe I did miss something. Has the UK capsized and everybody drowned so the source is gone ? Sorry not having TV (a total waste of time) so I could not notice such an event ;-)
Great work for the future!
Now you can really buy 2519s from Unicorn relatively inexpensively, unlike eBay. But what happens if that chain (UK broker - Unicorn) breaks, someone buys out all 5,000 2519s, waits a year until they run out at Unicorn and starts dictating their price? If I had $90000 I would. When I started getting interested in this topic the 2519 was $26 on eBay, now there are no offers under $100, which means the price has almost quadrupled in 3 years! Good thing we still have Unicorn, but it may not be at any time. Also, thanks to the availability of Russian boards, now replicas are being assembled all over the world, including countries where it's very problematic to buy something in the U.S. store. I sent my kits to Hungary and Australia last week. Now thanks to 2519 SMD Replacement they can assemble a replacement for about $20 and if necessary leisurely search for an acceptable offer on the original chip.
@natas666: good job, as we discussed via email.. :-)
Well, the answer to the question is: "why not?"
As Macintosh_nik pointed out, sooner or later it might become difficult or too expensive to get them, especially here in Europe where there are custom fees for non-EU countries (UK included).
And maybe before spending a lot of money for a single IC (maybe date-correct because maybe I'm restoring an original) I want to be sure it's actually broken.
By the way, I did some arithmancy: the bare cost of the components for a single unit is around 5 EUR/each at the most, without doing tricks to have more units on the same PCB.
By producing larger quantities (without not being in a hurry) the price would drop well below 4 EUR/each.
Anyway, I did it (and I will do more things like that) because I had time to do it, because I enjoyed it, and because I already had other orders in progress in China, not because I wanted to make a business out of it... :-)
Replacement is intended as a temporary and emergency measure, or for troubleshooting... we all want our Replicas "clean" and without any gimmicks.
Enjoy,
C.
Also many people that started with building Apple 1 1:1 replicas have 2 or more boards.
The idea is to have one optically as original as possible (maybe even with defekt parts).
Have one as close to original in working condition.
And have one to play with all kinds of extensions.
Late 2023 update: now that the 2519 is $65 + shipping on eBay, this kind of replacements make financial sense.
If you use some kind of feet for your Apple-I you can mount this replacement hidden below the PCB. The left socket (7404) is only for staybility and not electrically needed.If you want to place some broken or cheap IC in the socket you can drill hole (as big as possible) into the IC from the bottem without piercing the surface and before inserting this dummy check if really no pin has continuitiy to any other.
Hi,
well, not really... ;-)
The connection to the 7404's socket is required to connect the GND, which isn't present on the 2519 socket.
In fact, the 2519 works with an archaic technique called 'current well/pit' (I'm not sure of the English translation) and only has +5V and -12V as power supplies, no Ground.
To make the 6 shift registers work properly, it is therefore mandatory to connect a GND.
Of course, if you place the replacement circuit under the PCB, you can pick it up from somewhere else and not necessarily from the 7404 socket.
Regards,
Claudio - P-LAB
Speaking of which, I am curious: what did you use for the pins/connectors that plug into the original IC sockets?
I found something like this:
https://www.cnctech.us/productdetails.asp?ID=736
-Erik
Yes, that kind of connector is fine and doesn't damage the sockets.
Alternatively, if you plan to solder it under the PCB, you can consider the classic "Arduino style" square pin connectors that could be cheaper.
BR,
C.