Transistor equivalent

[spec]

Would you mind making components list fastly? my brother will arrive Hanoi in 18-1, so I thing I should know before 15-1.

will do

 

[Nikolai Petrenko]

will do

Thanks.
My EI transformer core size is: 5.8x3.2cm

 

[Nikolai Petrenko]

My EI transformer in a cheap half waves rectifier car battery charger. It is noisy, I think this problem cause by iron laminations weren't pressed firmly enough, and magnet wires don't make good contact to the core's insulator.

 

[spec]

Thanks.
My EI transformer core size is: 5.8x3.2cm

My EI transformer in a cheap half waves rectifier car battery charger. It is noisy, I think this problem cause by iron laminations weren't pressed firmly enough, and magnet wires don't make good contact to the core's insulator.

Hi Nikolai,

Sorry to say that the battery charger transformer will not be suitable for a high end audio amplifier. The transformer is one of the foundation components. The buzzing, if what I think it is caused by, should be quite easy to fix unless the transformer is being run close to the core saturation points (negative and positive). As a matter of interest though, are the dimensions you give for the core that the wingdings go on? Can you post a picture of the transformer?

 

[Gasboss775]

Out of interest and since BF199 were mentioned in the original post. Tayda electronics still sell them. I have bought from them before and they are reliable. Based in Thailand so shipping a bit slow, though you can pay US$18 for 3-4 day shipping from DHL.

Here's a link: Tayda Electronics: BF199

They also still sell "through hole" jfets, though certain stocks have exhausted now and I don't think anyone is making through hole jfets anymore, though I could be wrong as Farnell ( AKA Element14 / Newark ) are still selling a few through hole jfets at the moment.

 

[KeepItSimpleStupid]

The battery charger transformer is probably made to be intentionally lossy or "energy limiting".

 

[spec]

Out of interest and since BF199 were mentioned in the original post. Tayda electronics still sell them. I have bought from them before and they are reliable. Based in Thailand so shipping a bit slow, though you can pay US$18 for 3-4 day shipping from DHL.

Here's a link: Tayda Electronics: BF199

They also still sell "through hole" jfets, though certain stocks have exhausted now and I don't think anyone is making through hole jfets anymore, though I could be wrong as Farnell ( AKA Element14 / Newark ) are still selling a few through hole jfets at the moment.

Hi Gordon- hope there is no flooding where you are: horrific pics on the TV.

Thks for info. Now that Nikolai is going for a main-line distributor I will be able to improve the performance of the power amp no end. The first thing will be a change of output transistors (know type) and drivers. The driver and the VAS transistors are always a challenge because they are generally not a high-use device. Its a three corner compromise between Hfe, ft & VCE. Many of the really good drivers from Tosh are no longer in production. Still I expect ON will have something suitable. Are you a HiFi type person?

PS like the cat- what is his name?

 

[spec]

The battery charger transformer is probably made to be intentionally lossy or "energy limiting".

Yeah, that's what I though- some low grade cheap material- the exact opposite to what is needed. A nice jucy microwave transformer would probably do the job, but may be too large for a reasonable size case, if not a torroid.

 

[Gasboss775]

Hi Gordon- hope there is no flooding where you are: horrific pics on the TV.

Thankfully not, though we did experience some local flooding in December, though nothing like the stuff in Aberdeen this week or in the north west of England last month. Worst flood we've had was in 2006, quite a few houses were seriously damaged that time, though we were lucky, just couldn't get in and out of the area we live in for a day or so. At that time the local authority said it was only a 1 in 100 years type event so they couldn't justify the expense of flood protection measures. That seems questionable now, given recent events. The flooding in December last year was perhaps equivalent to 2/3 of the scale of the 2006 flood.

Are you a HiFi type person?

Sort of. I joined DIYAudio.com last year and have been learning a lot of stuff about amplifier design. Still not knowledgeable enough to build something decent yet. I did design and build a prototype Class A amplifier, but it was a crude and inefficient thing with an emiiter follower and resistive load for the output stage. About 40 Watts in, about 2.5 watts out! It did work though and didn't sound horrifickly bad to me, some audiophiles might beg to differ.

Sadly, Bonnie the cat in the picture died a couple of years ago at the respectable age of 18 years. She is still missed. We have another cat, Cheeky. I had a picture of him as my avatar before the one of Bonnie.

Gordon.

 

[spec]

Thankfully not, though we did experience some local flooding in December, though nothing like the stuff in Aberdeen this week or in the north west of England last month. Worst flood we've had was in 2006, quite a few houses were seriously damaged that time, though we were lucky, just couldn't get in and out of the area we live in for a day or so. At that time the local authority said it was only a 1 in 100 years type event so they couldn't justify the expense of flood protection measures. That seems questionable now, given recent events. The flooding in December last year was perhaps equivalent to 2/3 of the scale of the 2006 flood.

Good news about no flood. We lived in a bungalow, a couple of years ago, and were only saved by the elevated railway track 40 feet from the back of the house. All the houses south of the track got flooded, but the environmental agency did a fantastic job and installed pumps, pipes and dams all over the place. It was difficult to sleep at night because of the constant drone of the diesel engines driving the pumps. They managed to keep the water to just below damp proof course. So all the garages were flooded a couple of inches but the houses were ok. Many people were evacuated because of electricity danger. It was a very impressive operation- some of the pipes where a couple of feet in diameter. Apparently, they only managed to save the houses because they could pump the water into a rhyne a half mile away which led to the sea, about three miles away.

Sort of. I joined DIYAudio.com last year and have been learning a lot of stuff about amplifier design. Still not knowledgeable enough to build something decent yet. I did design and build a prototype Class A amplifier, but it was a crude and inefficient thing with an emiiter follower and resistive load for the output stage. About 40 Watts in, about 2.5 watts out! It did work though and didn't sound horrifickly bad to me, some audiophiles might beg to differ.

DIYAudio= good site. I have been with them for years. Some incredible stuff there. Yea, single ended class A is dreadfully inefficient but I suspect you are under selling you class A amp- it should sound superb, but perhaps limited on power and output current (2x theoretical is good)

Sadly, Bonnie the cat in the picture died a couple of years ago at the respectable age of 18 years. She is still missed. We have another cat, Cheeky. I had a picture of him as my avatar before the one of Bonnie.

That's the trouble with pets, unless you have a tortoise, elephant, or parrot, they don't live that long. There was s fantastic cat that the kids opposite named Wolfie. He just showed up one day and moved in with them. He used to stroll into our house as though he owned the place, often staying all day and night.

If you had a conversation he almost joined in, looking from one person to the other in line with the conversation flow. If I was working on the car he would come and supervise. Once when I was changing the plugs, he insisted on sitting on the rocker cover; would he move- no.

He had no fear of anything, including traffic. One summer he was asleep in the shade of the tyre of a delivery van parked on the drive opposite. The driver didn't know Wolfie was there and drove over him!

 

[Nikolai Petrenko]

Picture here:

 

[Nikolai Petrenko]

Microwave oven transformer too big and hard to disadsemble

 

[Nikolai Petrenko]

Microwave oven transformer too big and hard to disassemble, and hard to asessemble again. Toroid is the best so I continue to find it

 

[spec]

Hi Nikolai,

That transformer is not good enough in all respects for an audio amp, but would probably be Ok for making a bench power supply for example. Yes, I think a torroid is the way forward.

 

[spec]

Hy Nikolai,

I think you should use an LME49810 driver chip for your power amp.
Not only will this give predictable audiophile performance but also a power amp PCB design is available from Texas Instruments.

Don't confuse the LM49810 with single chip audio power amplifiers. The LME49810 is a true thoroughbred. If you do go this way can you make a sterio set for me too

The output transistors I would recommend are MJL3281A (NPN) and MJL1302A (PNP)

https://www.ti.com/lit/ds/symlink/lme49810.pdf

 

[spec]

Here is the first stab at the Bill Of Materials (BOM) for your 70W pre and power amplifier, but it does not take into account any decision you might make about the LME49810 in post #715 above.

​

 

[audioguru]

The LME49810 as the driver in a power amplifier "might" make a good audio amplifier. But the datasheet has spec's only for the driver IC with no load. They should have shown spec's for an entire power amplifier with certain power supply voltages and an 8 ohm load. They should recommend certain output transistors.

 

[spec]

The LME49810 as the driver in a power amplifier "might" make a good audio amplifier. But the datasheet has spec's only for the driver IC with no load. They should have shown spec's for an entire power amplifier with certain power supply voltages and an 8 ohm load. They should recommend certain output transistors.

You just killed this project- I hope you are happy now!

 

[audioguru]

The datasheet for the LME49810 driver IC is not marked "preliminary" so why wasn't it finished to show the spec's and pcb for a very good amplifier?? Is TI waiting for an audiophile to do it for them? I notice that National Semi made the unfinished datasheet almost 9 years ago. The "soft clipping" photo on the datasheet shows hard clipping, not soft clipping. Did you notice on TI's datasheet that it is discontinued? Digikey has none but Newark still has a few in stock.

 

[Gasboss775]

The battery charger transformer is probably made to be intentionally lossy or "energy limiting".

This is an interesting if rather crude approach to voltage / current limiting.