I see the MJ15003/4 are back in stock at Digi-Key, albeit at ridiculous prices ($10). These were once my favorite audio transistors, and they are still capable of excellent audio today. The MJ15024/5 are slightly less expensive ($8), probably because they have slightly lower current ratings.
However, I don't see TO-3 transistors in any equipment from the past two decades. I expect that old designs are the only things keeping these transistors in production.
Given the comments about fakes, would you trust TO-3 transistors today?
Ed
However, I don't see TO-3 transistors in any equipment from the past two decades. I expect that old designs are the only things keeping these transistors in production.
Given the comments about fakes, would you trust TO-3 transistors today?
Ed
From a proper distributor like Digi-Key yes.
From auction sites no way.
These TO-3 parts are being made for repair and long term manufacture of military and aviation "professional" equipment, not the audio industry
From auction sites no way.
These TO-3 parts are being made for repair and long term manufacture of military and aviation "professional" equipment, not the audio industry
That certainly explains the prices. 😉
ETA: I know that the toroidal transformer manufacturer that I buy from seems to cater to medical equipment manufacturers.
Ed
ETA: I know that the toroidal transformer manufacturer that I buy from seems to cater to medical equipment manufacturers.
Ed
Sometimes I repair city/state/school_system equipment and they are not allowed to "buy new" (unless already included in that year´s preapproved budget) so they must patch and repair whatever they have.
No that big deal with pure Electronics, a mess with "mechanicals" (speakers, turntables, tape and cassette players, etc.)
Don´t start me on Video Projectors 🙄
No that big deal with pure Electronics, a mess with "mechanicals" (speakers, turntables, tape and cassette players, etc.)
Don´t start me on Video Projectors 🙄
Mounting and wiring a TO-3 transistor is a waste of time and material. They were used for a while because most plastic parts did not have high power ratings, but that is no longer true. Gone is point-to-point wiring and more recently through-hole circuit boards. Connecting to the collector required using the screws, a bad idea. DIY'ers will continue to use up their junk box parts, but TO-3 is history in professional manufacturing. Before I retired, I worked on stuff that required a microscope, and that is the way of the future. Handmade is not just expensive, it is becoming impossible.
TO-3 is the most beautiful transistor ever made
numerous manufactures still making them and trusted
numerous manufactures still making them and trusted
"They were used for a while" ..... like from ... say ..... late 50's to present day?
That makes for some quite extended "while" , don´t you think? 🙂
stuff that required a microscope, and that is the way of the future.
Can you make a 100W (or larger) amp with microscope viewable parts?
Wow!!! 🙂
Personally I would not mix "brain" with "muscle" requirements.
Microscopic processors? .... any day of the week.
Microscopic power devices? .... only if liquid nitrogen cooled.
That makes for some quite extended "while" , don´t you think? 🙂
stuff that required a microscope, and that is the way of the future.
Can you make a 100W (or larger) amp with microscope viewable parts?
Wow!!! 🙂
Personally I would not mix "brain" with "muscle" requirements.
Microscopic processors? .... any day of the week.
Microscopic power devices? .... only if liquid nitrogen cooled.
From reputable sellers like RS Components and Farnell, I would buy them. Though I did buy several MJ21193/4 a while back when they were around £5 or so. Buying 100 brings the prices back down from £9 currently to £6.60, so group purchase might be a way forward.
I've not had any problems with TO-3+mica+thermal paste and screws - amplifiers built even 40 years ago still working (though the PSU has been upgraded a couple of times and the original 3055's removed about 20 years ago to allow for higher performance).
Only change to plastic when prices were lower, they do have one advantage in requiring only one screw, but using ally angle to mount the devices permits using either type on modern finned heatsinks with a flat surface.
DIY-ers will still use PCB's or point-to-point prototypes. The only possible replacement I suspect is metal substrate PCB's with surface mount devices, but they still won't be microscopic!
Class D will not excite too many hifi enthusiasts, either, I suspect, though there are one or two good designs out there. One I've heard boasted .003% THD or thereabouts, and was pretty indistinguishable from my Class AB. But it wasn't small, either.
I've not had any problems with TO-3+mica+thermal paste and screws - amplifiers built even 40 years ago still working (though the PSU has been upgraded a couple of times and the original 3055's removed about 20 years ago to allow for higher performance).
Only change to plastic when prices were lower, they do have one advantage in requiring only one screw, but using ally angle to mount the devices permits using either type on modern finned heatsinks with a flat surface.
DIY-ers will still use PCB's or point-to-point prototypes. The only possible replacement I suspect is metal substrate PCB's with surface mount devices, but they still won't be microscopic!
Class D will not excite too many hifi enthusiasts, either, I suspect, though there are one or two good designs out there. One I've heard boasted .003% THD or thereabouts, and was pretty indistinguishable from my Class AB. But it wasn't small, either.
No confidence on my side.
I work in maintenance and when I see the number of manufacturers who have turned to alternative suppliers during the covid crisis (due to the shortage and the production plants have stopped) and when I see the result today today is scary.
I very often work with Daikin, which I consider to be a serious manufacturer and very Japanese in mentality, they never do anything at random, and well today it's a real disaster in terms of reliability and they still can't solve the problems of "alternative" components and I am talking about modern components, so imagine for obsolete components which only interest a market of amateurs knowing that all production has already struggled to provide current and modern components. ..
there is also the possibility that the supplier got hold of a stock from a broker.
I continue to buy all the interesting wrecks that I can to have a sufficient stock of components until the end of my days and I will work to give everything before I die unless my children are interested in it.
I work in maintenance and when I see the number of manufacturers who have turned to alternative suppliers during the covid crisis (due to the shortage and the production plants have stopped) and when I see the result today today is scary.
I very often work with Daikin, which I consider to be a serious manufacturer and very Japanese in mentality, they never do anything at random, and well today it's a real disaster in terms of reliability and they still can't solve the problems of "alternative" components and I am talking about modern components, so imagine for obsolete components which only interest a market of amateurs knowing that all production has already struggled to provide current and modern components. ..
there is also the possibility that the supplier got hold of a stock from a broker.
I continue to buy all the interesting wrecks that I can to have a sufficient stock of components until the end of my days and I will work to give everything before I die unless my children are interested in it.
The effort of mounting TO-3 is not important for my hobby projects. I am considering switching from perf board to PCBs. I can build my designs as long as through-hole components are still made.
TO-3 is a very nice package. The TO-3 transistors in my old amplifier are much of the reason why I have not built my new design.
Ed
TO-3 is a very nice package. The TO-3 transistors in my old amplifier are much of the reason why I have not built my new design.
Ed
I recently bought some mj21193,4 from Mouser for an amp I am designing to replace an original. Onsemi packaged them in Mexico with a 22 date code.
We are very fortunate that they are still in production when most mfg use the plastic packages due to cost and ease of use.
I know exicon discontinued the metal can stating increased costs and decreased demand, leaving only the plastic parts available.
Bottom line, only buy from authorized distributors or buyer beware.
We are very fortunate that they are still in production when most mfg use the plastic packages due to cost and ease of use.
I know exicon discontinued the metal can stating increased costs and decreased demand, leaving only the plastic parts available.
Bottom line, only buy from authorized distributors or buyer beware.
I wouldn’t design them into anything serious where large numbers of them are required. Those prices are going to continue to skyrocket, and most of the audio types will simply go away. It will likely be a race to see which ones are the last to fall, the 15024/5 or the 21195/6. That will depend on how much industrial/military equipment the 15024 has actually been designed into. In any audio use still being considered, the 21195/6 can replace any of them. The few non audio types (2N5686, 2N5038, BUV21, etc) that are still holding strong may actually endure because of their traction in older, non-replaceable equipment for the military. But the PRICES on those parts are already going from the ridiculous to the sublime.
I have my stash, pretty much a lifetime+ supply. Mostly used a few at a time. There may be a project or two with say, 20 of them some time in the future - but I’m not looking forward to all that drilling.
I have my stash, pretty much a lifetime+ supply. Mostly used a few at a time. There may be a project or two with say, 20 of them some time in the future - but I’m not looking forward to all that drilling.
Honest Chinese vendors do exist. Last year I wanted some extra 15022's to back up what I had on hand. An eBay vendor in China I had bought from several times prior had some at 1/4 of Digikey's price. I asked him if he would refund me if they were fakes. (Most eBay vendors will not even reply when asked this.) He said, yes of course. I got them and they check out fine.
Considering an order of 100-200 2N3055H or 2N3773 from BEL India, supposedly the successors of old time USHA-UR which gave me excellent results.
Not for new designs but as backup to keep repairing old workhorses, still in use by customers.
Dragging my feet only because of the red tape involved 🙁
Not for new designs but as backup to keep repairing old workhorses, still in use by customers.
Dragging my feet only because of the red tape involved 🙁
@JMF:
Usha/ (UR), or really Usha Rectifier was a private company based in Delhi, now defunct.
BEL is a Government owned defense company, and they start with their own silicon, super quality.
They have their own refinery for silicon, it seems.
No relation to UR at all.
There is also CDIL, considered good.
There was a post here, UK price for CDIL made 2N3055 was 1.92 GBP, IIRC.
Supply to civilian market from BEL is erratic, they are busy with their own defense related orders.
Price is about 50 cents each, local market, small quantities, for CDIL made devices.
The CDIL web site did not have 2N3055 in TO-3, only TO-220, so what is available is old stock...or they forgot to put it on the site!
See if equivalents in European or American series are available, shipment to Argentina from India is expensive.
You have to consider the landed cost at your end...
Usha/ (UR), or really Usha Rectifier was a private company based in Delhi, now defunct.
BEL is a Government owned defense company, and they start with their own silicon, super quality.
They have their own refinery for silicon, it seems.
No relation to UR at all.
There is also CDIL, considered good.
There was a post here, UK price for CDIL made 2N3055 was 1.92 GBP, IIRC.
Supply to civilian market from BEL is erratic, they are busy with their own defense related orders.
Price is about 50 cents each, local market, small quantities, for CDIL made devices.
The CDIL web site did not have 2N3055 in TO-3, only TO-220, so what is available is old stock...or they forgot to put it on the site!
See if equivalents in European or American series are available, shipment to Argentina from India is expensive.
You have to consider the landed cost at your end...
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In all reality the toshiba and onsemi 150w devices in the to-3p are the most economical for any new amp designs. The wolverine folks even say they are the best performers. Just use 3 pair instead of 2 x 200w mjlx281 in the to-264.
Legacy designs using to-3 I guess you’re stuck with them 🙂
I do not recall ever getting bum parts off eBay suppliers but on old 2sx Japanese to-3 devices you are taking a chance for sure.
Let’s just say imo the to-3 should be in the not recommended for new design grouping, for maintenance only as previously mentioned.
One can say for sure onsemi must have some big orders to still be making them.
I have never used a semi from India, one day, I see new for me German mfg such as diotech at mouser for small signal
Legacy designs using to-3 I guess you’re stuck with them 🙂
I do not recall ever getting bum parts off eBay suppliers but on old 2sx Japanese to-3 devices you are taking a chance for sure.
Let’s just say imo the to-3 should be in the not recommended for new design grouping, for maintenance only as previously mentioned.
One can say for sure onsemi must have some big orders to still be making them.
I have never used a semi from India, one day, I see new for me German mfg such as diotech at mouser for small signal
FWIW, I thought a TO-247 would drop into a TO-3 location with minor adjusting, assuming the heat sink side faces the right way.
The 2SC5200 has amazing specs, is inexpensive ($3), but comes in a plastic package. It is clearly winning on performance/cost.
The MJ15003 is still very good (more than good enough for audio). I think it is a decent choice if one does not mind the cost.
Ed
The MJ15003 is still very good (more than good enough for audio). I think it is a decent choice if one does not mind the cost.
Ed