Has anyone got any photos of the original capacitors on the Apple 1 ?
I am specifically interested in the ceramic and the 47pf Mica.
Has anyone got any photos of the original capacitors on the Apple 1 ?
I am specifically interested in the ceramic and the 47pf Mica.
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Why not here? We also need this information
of course you may get that informations too. vview the related pages listed at:
i just can´t repeat here entire webpages....
and i have published this link here in another thread several weeks ago....
Sorry Thank you! ^_^
you probably just missed that thread...
Are you interested in the "classic" ceramic capacitors or the plastic film ones used in the NTI version? I'm planning to build a NTI version and I'm investigating the latter.
I am interested in the Pre NTI version.
I would like a picture of the writing on the ceramics.
I now have a set of the Phillips electrolytic.
I queue up for the same info but concerning greenish NTI caps
BTW, concerning big Sprague caps, anyone knows what alternative values would work in place of 2400uF and 5300uF? For voltage, any equal or higher value is fine but for capacity?
For the electrolytics caps, you can use higher capacity.
this is only partially valid....
for the big electrolytic capacitors a stepup to the next higher value is O.K. ,
so you may use instead of 2500 µf => 3300 µF
and for 5300 µF you may use instead => 5600 µF or the more common 6800 µF.
But you should not use higher values....
when powerup happens - this capacitors draw high current while loading up to default voltage and
this "spike" could kill the rectifier diodes, if you use for example double high values like
4700 µF and 10.000 µF.
The chance to use other values depends to the function the capacitor has to fullfill.
For example using higher values for the filtering capacitors ( the ceramic ones with 100nF ) or sometimes noted as
0,1 µF or other common notation 104 . Using there higher values drop efficiency for filtering the noise away from the
Same is valid if the capacitor is used in frequency dependant filters
( like the ones besides the 74LS123 ( or 74123 ) and close to the crystal ....
the change of those values will have direct effect to pulse duretion ( at the 74123 )
and damage the correct timing
- or the inability to operate at the determined frequency ( at the crystal ).
so a change od values is not realy permitted in general.... it realy depends to function and location....
I did some quick measurements and calculations and spec sheet scanning.
It takes about 30 milliseconds on my Mimeo to charge the 5300 UF cap to roughly 11 volts. Doing the calculations gives a current of roughly 10 AMPs averaged over those 30 milliseconds.
The A14F rectifiers that I am using are normally rated to 1 AMP, however they are rated to 50 amps for a one cycle surge (60HZ) and 4 amps for 8.3 msec
Because of the way the specs are made, it appears that the stock 5300 UF cap exceeds the rectifier's ratings, since the charge takes more than 1 60 HZ cycle (16 milliseconds). On the other hand, the 50 AMP rating would seem to indicate that there might be some margin left in the design, since we are only charging at 10 AMPs, not the full 50.
This is an interesting exercise and one I would take seriously, if I were designing new equipment, but something that probably isn't going to cause you trouble, unless you far exceed the original values.
This was my primary concern, but given that voltages involved are relatively low and in the NTI version 8 x A14F seem to be used, do you think it could be safe to even double the caps value?
The A14F has peak surge current rated at tens of Amperes.
ops... didn't note that Mike W. already provided an answer
thanks for adding the results from your research......
the thing i mention about is rather more not the fact of one single "loading cycle"....
this happens each time the computer is switched on ! So we are talking about a repeating event !
this surely won´t cause damage with the first several "power ups"... but what happens in fact is
that the limits are repeatingly exceeded if too large values of the caps are inserted and each single
exceeding causes "micro damage" (*)within the diode and such small damages don´t heal but sum up by time ...
... and that shortens life of the device rapidly....
a diode that might last for 5 to 10 years in "normal use" will fail sooner after probably 1 or 2 years
if the values are exceeded that far.....
why do the consumers always believe that electronic devices have eternal lifetime ? That´s not true....
- using wrong values was for years a common trick to shorten down "time of life" for such devices
and you can do that by exceeding electrical limits or for capacitors for example also by exceeding
surrounding temperature.... if you want reliable electronics you should keep within electrical limits.....
..... everybody doubting about this should "google" the topic about obsolescence and learn careful about that topic...
of course with the stuff at google you won´t be able to get details like explained here by me, but it at least explains about what i´m talking about... the rest can be researched by scientific examinations on the physics of electronical devices within universities....
(*) small changes in the siliciumoxid transient areas
As you say a higher voltage will work fine, and you can use a larger capacitance value, but not too large.
Its a common misconception that throwing the largest value capacitor will make for a better power supply, this works in theory, but in practice the larger the Cap the more the power diodes have to supply higher current to charge the caps. Peak current in the power diodes can double or triple as the capacitor size climbs, this is OK if you take this into account in your design, by replacing both the diodes and the transformers.
I remember as a radio trades apprentice thinking just this. Build a power supply, rated at 5V, 3A, use 5A diodes to be safe (as this turns out this was 1977 and used an LM323 regulator). Pick a transformer with 8V with a 3A secondary. Throw in the biggest electrolytic I could find and within an hour the transformer was near critical mass, with a surface temperature too hot to touch. One of the engineers working with me chuckled and reduced the main filter electrolytic to a much smaller value and the problem was solved, 4,700uF from memory.
The resultant voltage out waveform doesn't need to be super smooth, as long as the lowest point in the waveform is around 2V above the output voltage of the regulator the regulator will provide a nice smooth 5V DC out.
I wouldn't go more than 2X the capacitance in the original WOZ power supply circuit.
Can i use 2500uf at 35v instead 2400uf and 5200uf at 35v instead of 5300uf? Capacitance tolerance for both is (+30%, -10%). And Capacitance tolerance (+50%, -10%) for the 5x 25v 22uf it is a problem?
Yes you can use the alternate electrolytic capacitors you propose. I wonder if they are blue Spragues ? And if they are, are they still fitting in the Apple-1 PCB ? (Just curious)
I used to sell sets of three big blue electrolytic capacitors on Ebay, see:
... until I ran out of the 5300uF/15V ones. These sets had 2000uF/50V for the +12V/-12V supplies, which worked fine. My words of caution in that auction description may be helpful for builders venturing out on their own to find such capacitors.
IMHO, these 2400uF/25V capacitors, if old, and not inspected / reformed / ripple tested, are by far the most dangerous components in an Apple-1. A non-populated Apple-1 (empty IC sockets) gets close to their rated voltage, which is OK for new ones, fresh out of the factory, but 40+ year old ones without applying extra precautions and TLC may just explode in your face, and the shreds of aluminum foil may make nice shorts on your Apple-1 PCB. So be careful and heed my warnings !
A while ago, I ran an Apple-I using just 2 x 470uF in lieu of the 2400uF/25V ones, which is seen in this thread, post #1:
and it works just fine. As long as the valleys of the ripple voltage on these filter capacitors do not enter the dropout region of the regulators, they still can regulate and since the Apple-1 using the original transformer spec runs the regulators at a ridicolously high, or in other words, very generous, input voltage headroom, which makes the regulators run hot, you can always get away with using reasonably smaller capacitances for these three electrolytics. But you should never use higher capacitances, as the originally specified ones already are way too large and put the rectifier diodes at risk as pointed out by some posts above ... if the transformer can supply that current. Most transformers are too weak to blow these diodes up, but when they do, the diodes more often than not will fail as a short circuit, and if this happens, the next thing that blows up are your electrolytic capacitors. Which may be quite violent ... loud BANG! and a lot of mess from their shredded guts.
Purely coincidential, right now I'm experimenting which much smaller-than-specified blue Sprague capacitors to make a "flat looking" Apple-1 clone. Together with a lower profile heatsink on the LM323K this would fit into a better looking, low profile enclosure.
Nobody needs to use these "fat bastard" capacitors which are waaay oversized in terms of capacitance and looks, and then having the risks with those two who run somewhat too close to their rated voltage. Using higher voltage ratings always is safer. But don't overdo it, as the volume of the capacitors tends to go up with both more voltage and more capacitance.
Now, the purists may complain: "Buuuut .... the looooks .... incorrrrect !". They have a point here. But given the fact that experts like Cory can spot a clone from 10 feet away at the first glance - regardless how much effort you put into your "forgery" - my opinion is that we should allow ourselves some leeway, at least for cheap "builds for fun" which do not attempt to pass as originals. Making a "colorful candy" series of such cheap Apple-1 clones based on funny component colors is one of my next projects.
Finally, don't worry: the original SPRAGUE capacitors are still available new, from distributors like Mouser, despite Vishay now owns them, but if you want the 5300uF/15V one with exactly the 2.5" length, you have to buy a lot of them at once. There is a vendor from mainland China on Alibaba who sells the 5300uF/15V in pairs of two for below $20, but at the moment I don't find the link. He shows them in the original plastic trays as they came from the factory, so they most likely are genuine.
So no need to pay a King's ransom to the price gougers. Some of them ring up close $100 for a set of three. This made me so angry that I decided to show that these big blue capacitors can be sourced at a much cheaper price. This is why I sold a few sets ... just to show where the price point should be.
Thank you for your answer.
Nop, they are not blue. They are axial leaded 30mm (2500uf) and 39mm (5200uf) long and they are new.
You have done very good job in the thread you drive me to see. Congratulations!
... I finally found the link to the Chinese source for these SPRAGUE capacitors I did mention in my post #17 above:
Seems he has lots and lots of them. I did not try this seller out yet, but his merchandise looks genuine, so you give it a try and tell us about the outcome ! (And don't blame me if you get burned ! Only buy the minimum order initially and anticipate you may lose your money ... but if this vendor is honest we all want to know it !).
Note that the datecode on these capacitors is 9117, so they are 20 years old and past their "shelf life". I would not use them without the electrode reforming process and the the ripple voltage test. Which means extra effort, but the price is right, and they are still "Made in the USA". I've seen newer Sprague capacitors of the same type where this information is not present anymore, so we can assume that after Vishay acquired the Sprage capacitor business, they probably moved manufacturing elsewhere.
And here are a few of my "colorful candy" capacitors:
I see no reason why in a "for fun" Apple-1 build we should stick to the dull colors of the original bypass capacitors.
I'm chasing the 2400uF 25VDC caps - as old as I can find!
I stick with the new ones i found. I don't care for the original look capacitors to be honest. My goal is to build a working apple 1 replica (if I can), just for the fun of making and practice. That's why I use the gerbers I found in this forum.
I have those crappy old bastards :) and i was wondering if they are good fit on my replica. Tested and they seems ok. I dont know the volt rating.
And one more thing i want to ask is, can you post a link for a silver Mica please?
Those will work (and look) fine.
... I'm not sure if this is the same seller or if it's two sellers using the same photos (in which case one of them is a fraud).
Alas, my Russian language skills are not good enough to tell !
But thanks for your post anyway, it's good for the international Apple-I builder community to know which parts seller is honest and who is not.
I got that link from a builder in Europe who claimed that he bought his 5300uF/15V capacitors from that vendor.
Always keep in mind that if something goes wrong, it's not necessarily a fraud, I bought a lot of parts from China over the years and you would not believe how they scrambled up my name and address in some cases. Very few items did not arrive, though.
But more often than not I did not get the "genuine" item that was advertised, but something that was manipulated or a chinese made knockoff. Some CPLDs I bought as the (rare) 5V versions were relabeled 3.3V versions (laser engravers are cheap now) and the "genuine" Cherry blue line keyswitches were cheap chinese made knockoffs. I now have 10 of them for which I paid the ruinous sum of just a tad below $5 including shipping. I don't know whether I should throw them into the trash (they seem to work) or if I should finish by OSI Superboard II build with genuine Cherry keyswitches only.
This said, it is always prudent not to trust those alibaba sellers too much, meaning don't risk too much of your money.
... you have made !
Thanks for posting the pictures !
Maybe I "steal" your idea on how to mount the mine. At the moment I use small rubber feet fastened by screws (which go into the regular screw holes) but at least for one of my (now seven) Apple-I a nice mount or enclosure would be desired !
As for the forged ICs of Chinese origin, this is a scourge on mankind. I'm a retired chip designer and the (famous and reputable) company I worked for got customer complaints that our (excellent) opamps are crappy and do not meet spec. Guess what ? The Chinese had re-stamped super cheap and abundant 741 type opamps as one of our high-precision parts.
This also affects us Apple-1 builders. A builder in Australia told me that his "1404" shift registers he ordered in China were re-stamped 555 timers. Of course they did not shift, or time, in the Apple-1, but just got hot and died.
So, when dealing with China, "Buyer Beware".
(And they dare to call that "Silk Road")
Here are the capacitors I put in. Not blue but new :)
They look like the non-polar type used in audio.
They are polar. The marks are underneath and you can't see them. Maybe a bit in the middle photo.
I like the insulation you used over the legs of the Caps. Makes the install look professional.
It used to be common to see this on vintage electronics. Not so much today. Nice work!
Soldering looks pro as well. Good to see.
Here are a clean photo of the polarity marks.