Hi, maybe we can assume value to be 1$ a piece so a (probably virtual) 150$ in total for 20 year old parts. Now you will need to spend time and effort to find what the IC does and then find an application. The gain in the case of building something with 2 of these parts is 2$. Isn't having a certain application and then find a suitable part in the end resulting in less time, less effort, higher performance and possibly less money? It would be a pity to be busy for days and then discover the part (certainly the case if it is an opamp) has been vastly improved over the last 20 years 🙂
But then it could be a rare chip that people are willing to pay good coin for??
Or sometimes people are willing to spend the time on things like this as it's a challenge, fun or a learning curve 🙂
I've done that haha
I think that you are right here. I have been tinkering off and on with music synthesizer stuff and many of my test circuits use common TL072 type opamps. Maybe I'll stick one of these into one of the sockets to see what happens, but likely they will be trashed. Some friends and I used to hit the bankruptcy auctions when many of the small tech startups in South Florida died in the 80's and 90's. The likelihood of these being "rare chips" that are in demand today is virtually zero.
Meanwhile, I have found another TI mystery chip with a similar numbering scheme. I only have 4 of these and they were stuck in another tube with some Microchip parts.
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Exactly....
Remember one of my friend "back then" asked me to figure out if possible, a couple of custom number chips on
a PCB from Jaguar (Car) used for the cruise control. These boards burned constanly, and the prices from the
company was a disgrace. Never succeeded though, but would have added a nice little income 🙂
Maybe this is a stupid question, but can you not just call TI and ask them?
I spent 41 years working for Motorola. I couldn't even find a cross reference for our own in house numbers. They are rather closely guarded trade secrets. Well guarded so that your parts division can charge $10 for a $1 chip.
I worked in the cal lab at Motorola for 10 years. We had about 15 people and did our own repairs on everything used in the factory. When we had a factory shutdown event due to a backlog of sick test equipment waiting for parts I managed to squeeze a few generic part numbers out of HP for some logic chips in the HP 8656 RF signal generator. During the time when the factory grew faster than they could build buildings for it we had a full time HP guy whose territory was "Motorola South Florida." When I left Mot in 2014 the cal lab was gone, and all repair and calibration was outsourced to HP/Agilent/Keysight.
A high school friend worked in a large lithography operation in Miami that did color seperations, half tone screens, and made the printing plates for the magazine industry back in the late 70's. They had a large machine called a Hell Colormaster (if I remember correctly) that came from Germany. It routinely blew a PC board that drove one of 4 motors that probably moved laser beams. These boards contained some small parts and 4 large transistors on a heat sink. The PC boards cost a small fortune and took a long time to get. So my friend brought me a dead one to see what I could do with it. At the time it looked to me like an audio amp but was likely an H bridge. I simply went to see the in house Motorola semiconductor sales rep and asked for samples of the most powerful audio output parts that would fit the board. After fixing a few boards they never had another failure.
That might make sense since there were only 4 and in the same stick as some Microchip Variable Gain Blocks. The stick was in a box full of parts from a failed music synthesizer experiment.
Parts related, since you were an RF engineer, how would using these caps
in stereos or music instrument amps fair? They are the open frame
silver mica caps. To use or not to use, that is the question.
My intent is to not hi jack the thread.
S 12 J = 12pf,
S 22 J = 22pf and so on.
in stereos or music instrument amps fair? They are the open frame
silver mica caps. To use or not to use, that is the question.
My intent is to not hi jack the thread.
S 12 J = 12pf,
S 22 J = 22pf and so on.
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This reminds me of the Korg DW-8000's filter chip. It's an NJM part, but try getting a datasheet from either Korg or NJM, and neither can provide it. It was probably a custom chip made for Korg by NJM.
Those open frame caps were popular in RF amps back in the 70's through the 80's, but have largely been replaced by ceramics today. I doubt that this has anything to do with the quality of the cap. It's probably more about the desire to make everything smaller and cheaper today. Mica based caps had the lowest RF loss other than air back in the 70's. Some of today's high tech ceramics are better today but they didn't exist in 500 volt versions when I left the RF research world in 2014.
The picture shows an RF amp I made for Amateur Television in the 440 MHz range back in about 1980. There are several of those caps scattered about on the board. Other than possible moisture absorption and mechanical mounting issues they are probably fine to use in an audio amp. 12 and 22 pF however won't be found in too many audio frequency devices though.
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Hi and thanks. Interesting looking amp you have there also.
So was that with a copper shield on the back plane wrapped
to the top of the board that we see? Soldered to the copper
ground plane?
Was there a combination of mucho solder along with a
derating compound ?
Wondering how moisture would be an issue unless
they get warm - hot and the mica and silver cool at different rates
leads to moisture inside the folds, etc.
I've got a few pounds of these probably remove the mica's and melt
them for their scrap values.
Regarding the M1107 transistor, I've got a smattering of various transistors
from our friends at Motorola, some even have "sample" on the white circle.
Cheers,
Sync
So was that with a copper shield on the back plane wrapped
to the top of the board that we see? Soldered to the copper
ground plane?
Was there a combination of mucho solder along with a
derating compound ?
Wondering how moisture would be an issue unless
they get warm - hot and the mica and silver cool at different rates
leads to moisture inside the folds, etc.
I've got a few pounds of these probably remove the mica's and melt
them for their scrap values.
Regarding the M1107 transistor, I've got a smattering of various transistors
from our friends at Motorola, some even have "sample" on the white circle.
Cheers,
Sync
The board was a DIY effort that could not do plated through holes. At 440 MHz you need a good connection between the top and bottom ground planes. I used some U shaped tin stock that was used in the MX-300 radios to mount the option board to the main board. I put pieces all around the board perimeter and slobbered on lots of solder. There is a bunch of tiny tin rivets scattered around the board connecting the top and bottom ground planes. The M1107 transistor was a house numbered part that I pulled out of a dead mobile radio.
This board made about 50 watts from 440 to about 470 MHz when driven to hard saturation. I ran it at 444 MHz for Ham TV which was in its infancy back in the 1970's. NTSC TV required a linear amplifier, which this is NOT. It worked fine with the magic of a "sync stretcher" and by running the peak sync power at about 15 watts. There was a ham TV repeater about 15 miles from my house which I could reach at 10 watts of peak power. The FCC rules expressly prohibit music over the ham radio airwaves, but do not mention video games. Let's just say that some enterprising hams might have connected the video output of their Apple II clones up to a ham TV transmitter. Since those hams worked the evening shift at the Motorola plant, all those adventures occurred after midnight. Audio was live voice, since some games produced music.
This amp got hot and lived in the humidity of South Florida. It still works. I can't say would will happen to those caps it I tried to desolder them though.
This board made about 50 watts from 440 to about 470 MHz when driven to hard saturation. I ran it at 444 MHz for Ham TV which was in its infancy back in the 1970's. NTSC TV required a linear amplifier, which this is NOT. It worked fine with the magic of a "sync stretcher" and by running the peak sync power at about 15 watts. There was a ham TV repeater about 15 miles from my house which I could reach at 10 watts of peak power. The FCC rules expressly prohibit music over the ham radio airwaves, but do not mention video games. Let's just say that some enterprising hams might have connected the video output of their Apple II clones up to a ham TV transmitter. Since those hams worked the evening shift at the Motorola plant, all those adventures occurred after midnight. Audio was live voice, since some games produced music.
This amp got hot and lived in the humidity of South Florida. It still works. I can't say would will happen to those caps it I tried to desolder them though.