Further testing: 215W halogen bulb from B&Q comes in at 15R cold. I think thats what I'm going to use. I have 67V DC unloaded - will be interesting to see how much tat drops when loaded!!
I also found some 10r 50W resistors in the junk pile, so I ended up using those. There will be a bit of hit and miss, so may end up going back to 1 or 2 R depending. But the build is progressing well, I figured out a neat-ish way to hold the halogen stick bulbs, so hopefully that works out OK.
If I make progress tomorrow night I'll post a few more pics.
Fran
I also found some 10r 50W resistors in the junk pile, so I ended up using those. There will be a bit of hit and miss, so may end up going back to 1 or 2 R depending. But the build is progressing well, I figured out a neat-ish way to hold the halogen stick bulbs, so hopefully that works out OK.
If I make progress tomorrow night I'll post a few more pics.
Fran
mmm, I seem to have a problem.
Using a 230W 240V bulb, cold resistance about 15R. Turn on the amp, bulb lights up but drops nearly all the voltage. So I only get about 0.6v at the drain, about 0.47V at the source.
I've obviously done something stoopid! Feels like the bulb is starving her of juice.....
Fran
Using a 230W 240V bulb, cold resistance about 15R. Turn on the amp, bulb lights up but drops nearly all the voltage. So I only get about 0.6v at the drain, about 0.47V at the source.
I've obviously done something stoopid! Feels like the bulb is starving her of juice.....
Fran
Smoked or static got the mosfet? With power off check mosfet D-S if shorted...or D shorted to heatsink/ground?
HI
May be the resistance of bulb too big. I suggest you use about 25VDC to check the current passing thru your bulb, then calculate the resistance.
cheers
Coffin
Thanks guys. So I went back and substituted a big 15R 50W resistor for the lightbulb and it works OK now. I get a PS voltage under load of 47V and after the resistor of 23V. Voltage across the source resistor is 1.6V - bang on. The 15R gets hot - as does the mosfet too.
So obviously I have the bulb thing arseways. So with a somewhat clearer head tonight, I did a bit of ohms law calculation. So a 300W 120V bulb develops 2.5A across it (given 120V that is). So the get the equivalent for a 240V bulb, you would need a 600W bulb. I don't have a 600W one, but I do have a 500W one, so I will try that. I suppose I could also do 2 x 300 in parallel too.
I wonder if anyone else in a 240V country has sorted this one yet?
Fran
So obviously I have the bulb thing arseways. So with a somewhat clearer head tonight, I did a bit of ohms law calculation. So a 300W 120V bulb develops 2.5A across it (given 120V that is). So the get the equivalent for a 240V bulb, you would need a 600W bulb. I don't have a 600W one, but I do have a 500W one, so I will try that. I suppose I could also do 2 x 300 in parallel too.
I wonder if anyone else in a 240V country has sorted this one yet?
Fran
Tried a 500 w bulb - still big voltage drop. Paralleled 2 x 500w ones - that's better, now the voltage is up a but, but still to low at 12v after the bulbs. Going to try more later.
Fran
Fran
OK,
Its been singing for the past couple of hours and sounding pretty good, although only on crappy mission speakers in the workshop. It took 3 halogen sticks per channel - a total of 1300W each side!! So maybe a kettle element each side would have been good too.
The stats are:
50V secondary, 47V output under load. 22-23V before the output cap. 1.6V across the source resistor..... all seems good. Fets get to ~60degC on the cases, heatsinks are at 53degC - about 30-35 above ambient. So all seems pretty good really!
I do have one problem though - teabag are your reading this!! - I have some hum. Its not very loud (of course thats on relatively insensitive speakers) but will need to be fixed. So it looks like I might need an extra RC stage or something if you are correct teabag - i think you ended up doing that too, right?
Fran
Its been singing for the past couple of hours and sounding pretty good, although only on crappy mission speakers in the workshop. It took 3 halogen sticks per channel - a total of 1300W each side!! So maybe a kettle element each side would have been good too.
The stats are:
50V secondary, 47V output under load. 22-23V before the output cap. 1.6V across the source resistor..... all seems good. Fets get to ~60degC on the cases, heatsinks are at 53degC - about 30-35 above ambient. So all seems pretty good really!
I do have one problem though - teabag are your reading this!! - I have some hum. Its not very loud (of course thats on relatively insensitive speakers) but will need to be fixed. So it looks like I might need an extra RC stage or something if you are correct teabag - i think you ended up doing that too, right?
Fran
Attachments
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Sure, Mine had hum in the original schematic view.
It was cured via using 2x5600uf x .25 30W sandcast resistors-30,000uf-1R 25w 30,000uf.
This cured it.
I am rebuilding the supply to use both primaries right now, so I will improvise a bit on this. I will try 2x5600uf-2.2mH(L)-15,000uf-1R-1500uf on both sides.
It was cured via using 2x5600uf x .25 30W sandcast resistors-30,000uf-1R 25w 30,000uf.
This cured it.
I am rebuilding the supply to use both primaries right now, so I will improvise a bit on this. I will try 2x5600uf-2.2mH(L)-15,000uf-1R-1500uf on both sides.
OK, thanks teabag. I'm going hunting now for a few more caps to extend out the RC network. The hum is not too loud on the test speakers, but will be a problem on my horns. Sound is pretty sweet though....
Fran
Fran
Thats another thing to try out yet - I did get some 20N50Ds too...
I did a quick experiment - I added 0.47r>>6800uF and the hum disappeared. So I reckon if I added a couple of 10kuF caps I'd be aok.
I think thats what I'll do first, then go back and try the 20N50D after I've listened for a while. What Nelson says in the article about gain is spot on - I'd say you would want an active pre to make the most of this amp.
Fran
I did a quick experiment - I added 0.47r>>6800uF and the hum disappeared. So I reckon if I added a couple of 10kuF caps I'd be aok.
I think thats what I'll do first, then go back and try the 20N50D after I've listened for a while. What Nelson says in the article about gain is spot on - I'd say you would want an active pre to make the most of this amp.
Fran
And we have it right here too!
http://www.diyaudio.com/forums/diyaudio-com-articles/160464-de-lite-amplifier.html
A great thing about the amp is that it is encouraging some experimentation and variants. That means a successful amp design when it is for DIY'ers. I think that Nelson encouraged that by describing some variants in the article itself.
Thanks, Nelson!
http://www.diyaudio.com/forums/diyaudio-com-articles/160464-de-lite-amplifier.html
A great thing about the amp is that it is encouraging some experimentation and variants. That means a successful amp design when it is for DIY'ers. I think that Nelson encouraged that by describing some variants in the article itself.
Thanks, Nelson!
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nice!!!! i had the same idea too.
are your halogen sticks 110v type or 240v type?
For me, this is Nelson's best article so far, it really clarifies a lot of points Nelson has mentioned in the past.
They are 240V - just the common type available here (240V country).
the 10000uF caps arrived today so I'll be trying them out later I hope.
Fran
I am looking for commercial single ended solid state amplifiers with this topology and output transformer.
Until know I have found either only SE tube versions (extrem wide range of various models) or - if it is solid state with output transformers - only such in push-pull topology like Altec (post #88/85/84/83/82) and Dynacord (post #77) about
http://www.diyaudio.com/forums/soli...-models-quasi-complementary-power-output.html
and additional such with a small amount of output power (and small transformers) for the use in car- and portable radios like Motorora, Bendix and Delco-GM - for looking schematics go to post #24-27 about
http://www.diyaudio.com/forums/parts/167680-vintage-transistors-3.html
But which commercial brands/models there are in single ended SS topologies with output transformator above 6 Watt output power (both vintage and currently production)?
Here some URLs arround the Nemesis topology
2SK135 SE Amp
http://www.linearaudio.nl/nemesis-1.htm
http://www.linearaudio.nl/Nemesis/nemesis cct.bmp
HiFiForum.nu - Nemesis - 1-transistor SE-stärkare
http://www.diyaudio.com/forums/solid-state/193-hiraga-20w-class-13.html (post #123, #124 "le Super Nemesis")
About
http://www.diyaudio.com/forums/soli...ended-integrated-power-amplifier-devices.html
you will find only OTL versions.
And even about the SS SE circuit overview (mostly for diy) about
http://www.diyaudio.com/forums/soli...n-single-ended-solid-state-output-stages.html
very view topologies with transformer are to find.
A second question: For the correct calculating of such transformers there are other requirements necessary than for transformators used in PP stages cause it's DC biased condition while operating (idle current arround ten times higher than by tube SE stages).
Where I can find detailled basic articles arround this (pro and cons of torodial core and such with iron slices and different behaviour regarded permeability, pro and con of various air gap and so on)?
Thank you for your comments.
Special companies for such transformers used in tube SE you will find here (small overview):
Info zu Trafos
Audio Transformers
PLITRON - audio transformers - toroidal transformers - toroids - output transformers - current transformers - power transformers - medical isolation transformers - power toroids
Korato (see attachement and ask diyaudio member "ZEN-mod")
Röhrenverstärker Bausatz
Lundahl Transformers, audio transformer and tube amplifier transformer manufacturer
EXPERIENCE electronics - Single Ended Output Transformers
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Hi all,
I got some 6N50D2 depletion mosfets from Tea-Bag a while ago and i am about to begin the mounting of a De-Lite version 3 amp. As i want to box all the components, there won't be any bulb
to the drain of the fets so i will call it the De-Nite amp 🙄 Hope you like it... There will be some Mundorf M-Resist Supreme resistors instead. I will send pictures when the amp is completed.
Tea-Bag, how muc ripple do you get at the psu output with your last filtering network ? I plan to use one mains transformer and one Schottky bridge for both channels then there will be one 22000µF + double choke with 1 ohm DCR i.e. one half on the positive rail and the other half on the return path + 22000µF as filter for each channel. A simulation with PSU2D has shown less than 1 millivolt p-p of ripple with 2x0.05mH and only some tens of microvolts with 2x0.5mH. I have asked a french transformer manufacturer about how much inductance he could get out of a 2A 1 ohm double choke, i am waiting for his reply...
Regards, facelvega
I got some 6N50D2 depletion mosfets from Tea-Bag a while ago and i am about to begin the mounting of a De-Lite version 3 amp. As i want to box all the components, there won't be any bulb
to the drain of the fets so i will call it the De-Nite amp 🙄 Hope you like it... There will be some Mundorf M-Resist Supreme resistors instead. I will send pictures when the amp is completed.Tea-Bag, how muc ripple do you get at the psu output with your last filtering network ? I plan to use one mains transformer and one Schottky bridge for both channels then there will be one 22000µF + double choke with 1 ohm DCR i.e. one half on the positive rail and the other half on the return path + 22000µF as filter for each channel. A simulation with PSU2D has shown less than 1 millivolt p-p of ripple with 2x0.05mH and only some tens of microvolts with 2x0.5mH. I have asked a french transformer manufacturer about how much inductance he could get out of a 2A 1 ohm double choke, i am waiting for his reply...
Regards, facelvega