Gains, bandwidth and collector current substantially less... Are these often used in place for?
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Transistors - Bipolar (BJT) - Single | Discrete Semiconductor Products | DigiKey
TO251, TO252 would have the larger vas devices (and small/pre driver). Usual spec for vas, 4.5 to 15pf (or a third more for pnp)--the bigger of those would be in these larger packages. They are probably easy to solder.
You know, either smaller or larger size amplifier wouldn't need two different size devices for vas. So, what size room are we talking about?
TO251, TO252 would have the larger vas devices (and small/pre driver). Usual spec for vas, 4.5 to 15pf (or a third more for pnp)--the bigger of those would be in these larger packages. They are probably easy to solder.
You know, either smaller or larger size amplifier wouldn't need two different size devices for vas. So, what size room are we talking about?
Zetex/Diodes do a few good parts such as DZT5401/DZT5551.
As for heatsinking them, theres a few options - here's some
1) Use thermal epoxy and attach a heatsink made for SMD parts. There's plenty of those suitable for DPAK type devices which could be used.
2) Same heatsink, but get one slightly wider. Drill 2 holes through it, and have mounting screws that go through the board so that it clamps to the top of the SOT-223. You see similar arrangements used for PC graphics cards to cool the core supply MOSFETs.
3) Get a TO-220 heatsink which solders to the board (preferably one with a solid metal stud). Arrange it so it's around the SOT-223 part, and put a big enough plane down for the collector, on both sides of the board, with plenty of vias. Solder the stud into that plane.
Cascoding works very well and has very little disadvantages. If the loss of headroom really bothers you, a simple Cockroft multiplier works to produce the slightly higher voltage rails needed for the frontend.
As for heatsinking them, theres a few options - here's some
1) Use thermal epoxy and attach a heatsink made for SMD parts. There's plenty of those suitable for DPAK type devices which could be used.
2) Same heatsink, but get one slightly wider. Drill 2 holes through it, and have mounting screws that go through the board so that it clamps to the top of the SOT-223. You see similar arrangements used for PC graphics cards to cool the core supply MOSFETs.
3) Get a TO-220 heatsink which solders to the board (preferably one with a solid metal stud). Arrange it so it's around the SOT-223 part, and put a big enough plane down for the collector, on both sides of the board, with plenty of vias. Solder the stud into that plane.
Cascoding works very well and has very little disadvantages. If the loss of headroom really bothers you, a simple Cockroft multiplier works to produce the slightly higher voltage rails needed for the frontend.
Great scam, buy up all the stock and then your competition is screwed, , including us DIY. Start selling them at inflated costs on eBay 
I remember having purchasing, need to go to brokers to get supply.
Same issue with the MJL's.
Wow Mark,
300, life time buy? or eBay sales I usually order min 12, for repairs, new designs. I am running out of A1381, stocking up on c3503 for sure.
Not a fan of TTA(C)004B? They ran fine in my simulation with the Toshiba models, but are not A1381 grade for VAS. I'll order up some TTA(C)004B to use as pre-drivers for testing. Another one that goes in and out of stock. The more we order the better chance of them keeping them alive.
I remember having purchasing, need to go to brokers to get supply.Same issue with the MJL's.
Wow Mark,
300, life time buy? or eBay sales
I usually order min 12, for repairs, new designs. I am running out of A1381, stocking up on c3503 for sure.Not a fan of TTA(C)004B? They ran fine in my simulation with the Toshiba models, but are not A1381 grade for VAS. I'll order up some TTA(C)004B to use as pre-drivers for testing. Another one that goes in and out of stock. The more we order the better chance of them keeping them alive.
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Probably there was a sizeable price reduction beyond qty=250, I don't remember exactly.
I also bought 100 PNP + 100 NPN (and got immediate delivery) of those Toshiba TT00xxxx medium power devices, after Wayne mentioned them as possibilities.
In my mind, if a heaping big bag full of discrete devices costs less than one toroidal transformer, why not? I've got the room to store them.
I also bought 100 PNP + 100 NPN (and got immediate delivery) of those Toshiba TT00xxxx medium power devices, after Wayne mentioned them as possibilities.
In my mind, if a heaping big bag full of discrete devices costs less than one toroidal transformer, why not? I've got the room to store them.
This device looks like a damn good substitute for KSA1220A and there are thousands of them on the shelf at DigiKey and Mouser.
HOWEVER you will need to learn how to solder surface mount devices with a big wide power tab, to use it. You may have to lay out your own PCBs too,
Choice 1: "I'd rather sit, do nothing, and have no parts, than learn how to solder SMD."
Choice 2: "I'd rather learn how to solder SMD and have parts tomorrow".
HOWEVER you will need to learn how to solder surface mount devices with a big wide power tab, to use it. You may have to lay out your own PCBs too,
Choice 1: "I'd rather sit, do nothing, and have no parts, than learn how to solder SMD."
Choice 2: "I'd rather learn how to solder SMD and have parts tomorrow".
Great scam, buy up all the stock and then your competition is screwed, , including us DIY. Start selling them at inflated costs on eBay
Same issue with the MJL's.
Wow Mark,
300, life time buy? or eBay sales
Not a fan of TTA(C)004B? They ran fine in my simulation with the Toshiba models, but are not A1381 grade for VAS. I'll order up some TTA(C)004B to use as pre-drivers for testing. Another one that goes in and out of stock. The more we order the better chance of them keeping them alive.
This attitude I do not understand. Begrudging Mark the right to buy what he wants to buy?
I bought 500 pcs of KSA1381E in 2013 as a lifetime supply. It was probably $100 at the time. Feel free to hate me for buying what I want. Building on Mark's point, a good amplifier chassis is at least $200 and the large ones are more like $400+. it makes sense to me to stock up on the parts I like. I recently bought 200 pcs each of Toshiba 2SA970BL and 2SC2240BL in the original Japan sealed static bags. Spent last weekend binge curve tracing to find matched pairs at the voltage and bias current that I want to use. Curve tracing a couple hundred parts gives me a much better idea of how the devices behave than measuring just a few parts.
Sorry that the humor was lost on me. Different jokes for different blokes. Carry on.
...A string goes into a bar. He orders a beer but the bar tender says "We don't serve your kind in this bar." ......
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