Hi Dartagnan,
Sorry for the delay in replying, been away for a couple of days.,
Um, thought that might be the case.
These welded laminations aren't really suited for wide band low distortion audio use as the welding messes with the magnetic properties of the laminations. And the laminations themselves are probably not of the best quality.
Anyhow, try using the speaker windings two transformers, connected in the same manner, with the speaker connected across the ends.
I will try to set up this configuration but regret that it will probably not be until the end of the weekend at the earliest due to pressures of work and personal commitments.
Unfortunately it is likely that the windings will not be matched and whilst you may get some results it isn't going to be optimum.
Yes.
The issues with using these alternative transformers such as yours and toroids is that these can provide a good method of trying out the basic principles of how the amplifier works - BUT will not necessarily give an optimum configuration or best performance.
This is important to remember because the ultimate performance of the amplifier should not be solely judged on how well a test setup performs.
Don't apologize for a sensible question
Best wishes,
Susan.
Sorry for the delay in replying, been away for a couple of days.,
Dartagnan said:
Um, thought that might be the case.
These welded laminations aren't really suited for wide band low distortion audio use as the welding messes with the magnetic properties of the laminations. And the laminations themselves are probably not of the best quality.
Anyhow, try using the speaker windings two transformers, connected in the same manner, with the speaker connected across the ends.
I will try to set up this configuration but regret that it will probably not be until the end of the weekend at the earliest due to pressures of work and personal commitments.
Unfortunately it is likely that the windings will not be matched and whilst you may get some results it isn't going to be optimum.
Yes.
The issues with using these alternative transformers such as yours and toroids is that these can provide a good method of trying out the basic principles of how the amplifier works - BUT will not necessarily give an optimum configuration or best performance.
This is important to remember because the ultimate performance of the amplifier should not be solely judged on how well a test setup performs.
Sorry about the basic questions, but I don't have means of testing (or much know-how, really.
Thanks,
Dart
Don't apologize for a sensible question
Best wishes,
Susan.
Power Supply Requirements
Dear All,
When I was originally doing the design work for the amplifier I tried to collect as much information as possible on wide band audio transformers (not much as it turned out) and spoke to a number of people who were knowledgeable in this field.
One Guru told me that the most I could get was the 1/3, 1/3, 1/3 split in power with only a third to the output.
As one respects the handed down wisdom from those who are practiced in the art I accepted this statement and happily included it subsequent information - including a post at the beginning of this thread.
I did always have a bit of a niggle with this but just put this down to my lack of proper mathematical understanding in these matters (and the use of DVMs).
On reflecting about these power requirements I note that I have been happily hitting 20 volts RMS into 8 ohms in my recent testing sessions. BUT the fuse I have in the DC supply line is only 5 amps rating.
Um?
Using the 1/3 split regime with an additional 1.5 amps bias for the Toshiba Lateral FETS and 2.5 amps for the load I should have a total current drain of 9 amps.
Somewhat higher than the T1 20mm 5 amp fuse's rating!
Oops!
My world view crumbles at this point. So much for listening to perceived wisdom.
From my notes using my 2:1 step down transformer configuration the average measured current for 20 volts AC rms into 8 ohms is a mere 2.75 amps.
2.75 amps minus 1.5 amps bias = 1.25 amps.
The 2:1 ratio transformer trades voltage for current, so 1.25 amps x 2 = 2.5 amps which is correct for 8 ohms.
Ergo the amplifier is running at far greater than 1/3 power efficiency into the load.
With a 1 amp total bias (which is what I am figuring on using for the powermesh mosfets) 20 vac RMS into 8 ohms should be 2.25 amps average max (which is over unity as far as current goes compared to a straight solid state amp direct drive output). Peak currents are higher of course.
This is a much more satisfactory state of affairs than the supposed 8.5 amps I "should" be taking.
Um, sorry about that. Humble pie etc.
I will set out to make definitive measurements the next time I have my test rig out as I think I may be getting some regenerative power back from the back EMF of the flux transitions as well. And use a moving coil test meter.
Best wishes,
Susan.
Dear All,
When I was originally doing the design work for the amplifier I tried to collect as much information as possible on wide band audio transformers (not much as it turned out) and spoke to a number of people who were knowledgeable in this field.
One Guru told me that the most I could get was the 1/3, 1/3, 1/3 split in power with only a third to the output.
As one respects the handed down wisdom from those who are practiced in the art I accepted this statement and happily included it subsequent information - including a post at the beginning of this thread.
I did always have a bit of a niggle with this but just put this down to my lack of proper mathematical understanding in these matters (and the use of DVMs).
On reflecting about these power requirements I note that I have been happily hitting 20 volts RMS into 8 ohms in my recent testing sessions. BUT the fuse I have in the DC supply line is only 5 amps rating.
Um?
Using the 1/3 split regime with an additional 1.5 amps bias for the Toshiba Lateral FETS and 2.5 amps for the load I should have a total current drain of 9 amps.
Somewhat higher than the T1 20mm 5 amp fuse's rating!
Oops!
My world view crumbles at this point. So much for listening to perceived wisdom.
From my notes using my 2:1 step down transformer configuration the average measured current for 20 volts AC rms into 8 ohms is a mere 2.75 amps.
2.75 amps minus 1.5 amps bias = 1.25 amps.
The 2:1 ratio transformer trades voltage for current, so 1.25 amps x 2 = 2.5 amps which is correct for 8 ohms.
Ergo the amplifier is running at far greater than 1/3 power efficiency into the load.
With a 1 amp total bias (which is what I am figuring on using for the powermesh mosfets) 20 vac RMS into 8 ohms should be 2.25 amps average max (which is over unity as far as current goes compared to a straight solid state amp direct drive output). Peak currents are higher of course.
This is a much more satisfactory state of affairs than the supposed 8.5 amps I "should" be taking.
Um, sorry about that. Humble pie etc.
I will set out to make definitive measurements the next time I have my test rig out as I think I may be getting some regenerative power back from the back EMF of the flux transitions as well. And use a moving coil test meter.
Best wishes,
Susan.
Toroid Schematic
Dear All,
I have added a schematic to the toroid page:
http://www.susan-parker.co.uk/zeus-toroid-amp-1.htm
BW,
Susan.
Dear All,
I have added a schematic to the toroid page:
http://www.susan-parker.co.uk/zeus-toroid-amp-1.htm
BW,
Susan.
Any news on the Lundahl LL1922 input tran?
Hi Susan,
I'm in an ordering mood these days, but the Sowter 8160 is out of my price range and the 6-8 week wait is beyond my attention span.
The LL1922 sells for $80 ea. US and K & K Audio has them in stock. But, the big question is "Are they as good as the Sowter's?" A 30% savings is fine and dandy, unless I would end up ordering the Sowters anyway.
Did you ever get any new info from Lundahl or K & K?
Also, Jensen Transformers in Los Angeles is pretty famous for their professional audio transformers. Could you please take a peek at their products and see if any meet the needs for Zeus's input and output transfo's?
They are located only 30 minutes from my house (w/o traffic).
Hi Susan,
I'm in an ordering mood these days, but the Sowter 8160 is out of my price range and the 6-8 week wait is beyond my attention span.
The LL1922 sells for $80 ea. US and K & K Audio has them in stock. But, the big question is "Are they as good as the Sowter's?" A 30% savings is fine and dandy, unless I would end up ordering the Sowters anyway.
Did you ever get any new info from Lundahl or K & K?
Also, Jensen Transformers in Los Angeles is pretty famous for their professional audio transformers. Could you please take a peek at their products and see if any meet the needs for Zeus's input and output transfo's?
They are located only 30 minutes from my house (w/o traffic).
More on Jensen Transformers
I was specifically referring to some of their microphone input transformers like the $73 JT-115K-E:
or
$80 JT-110K-HPC:
The biggest problem is no center tap, but they will supposedly do simple mods to existing transformer designs for a modest fee.
I was specifically referring to some of their microphone input transformers like the $73 JT-115K-E:
or
$80 JT-110K-HPC:
The biggest problem is no center tap, but they will supposedly do simple mods to existing transformer designs for a modest fee.
Re: More on Jensen Transformers
Folks, you might also want to check out Lundahls LL7905.
This is a very high level mic IP tranny with 1+1+1+1 : 5.6+5.6
So with parallel prim to series sec you can get 1 : 11.2 with a
CT on secondary.
Data sheet specs max sec voltage at +37dBu (54.5V rms) so it
looks like it may work fairly well at the levels required for Susans
amp.
Here is data sheet:
http://www.lundahl.se/pdfs/datash/7905.pdf
Please note that in general, for mic IP transformers to work best
they are specified for a source impedance of 150ohms for
optimum transient response. This is particularly true with
Jensens as they have an almost perfect Bessell HF roll off when
used as such.
Further to this point, the output capacitance of MOSFETs that
this transformer drives may have to be compenasted for.
The best way to do this is to feed a 10kHz square wave and
adjust a snubber at transformer output for least amount of
ringing.
Cheers,
Terry
darkmoebius said:
Folks, you might also want to check out Lundahls LL7905.
This is a very high level mic IP tranny with 1+1+1+1 : 5.6+5.6
So with parallel prim to series sec you can get 1 : 11.2 with a
CT on secondary.
Data sheet specs max sec voltage at +37dBu (54.5V rms) so it
looks like it may work fairly well at the levels required for Susans
amp.
Here is data sheet:
http://www.lundahl.se/pdfs/datash/7905.pdf
Please note that in general, for mic IP transformers to work best
they are specified for a source impedance of 150ohms for
optimum transient response. This is particularly true with
Jensens as they have an almost perfect Bessell HF roll off when
used as such.
Further to this point, the output capacitance of MOSFETs that
this transformer drives may have to be compenasted for.
The best way to do this is to feed a 10kHz square wave and
adjust a snubber at transformer output for least amount of
ringing.
Cheers,
Terry
Re: Any news on the Lundahl LL1922 input tran?
Hi Darkmoebius,
Been looking into these posts.
Ordering is good
Um. I haven't used any Lundahl's but have heard good things about them.
However note the bandwidth of the LL1922 in 1:8 is 10 Hz to 30 kHz +/- 1.0 dB.
I don't know what the distortion levels are without comparing the two side by side on the bench but a 15 VA toroid has a bandwidth that is not a lot lower than this.
Only what's up on their website.
Would be very convenient.
I have had a good look and I can't see anything really suitable.
Some of the line stuff is half way there but nothing with a big enough core cross section for the step up. You could use a pair if you had some in a box but it wouldn't be cheaper than the Sowter solution which was specifically designed for this application.
The Lundahl's look better but their bandwidth is much lower.
I would note from the specs for the Sony DVP-NS955 that...
Frequency Response: Standard CD is 2 Hz to 20kHz(±0.5ｄB)
Frequency Response: Super Audio CD is 2Hz to 100kHz (50kHz: -3dB ±1dB)
... so the Toshiba Linear FETs don't hack it either.
Best wishes,
Susan.
Hi Darkmoebius,
Been looking into these posts.
darkmoebius said:
Ordering is good
Um. I haven't used any Lundahl's but have heard good things about them.
However note the bandwidth of the LL1922 in 1:8 is 10 Hz to 30 kHz +/- 1.0 dB.
I don't know what the distortion levels are without comparing the two side by side on the bench but a 15 VA toroid has a bandwidth that is not a lot lower than this.
Only what's up on their website.
Would be very convenient.
I have had a good look and I can't see anything really suitable.
Some of the line stuff is half way there but nothing with a big enough core cross section for the step up. You could use a pair if you had some in a box but it wouldn't be cheaper than the Sowter solution which was specifically designed for this application.
The Lundahl's look better but their bandwidth is much lower.
I would note from the specs for the Sony DVP-NS955 that...
Frequency Response: Standard CD is 2 Hz to 20kHz(±0.5ｄB)
Frequency Response: Super Audio CD is 2Hz to 100kHz (50kHz: -3dB ±1dB)
... so the Toshiba Linear FETs don't hack it either.
Best wishes,
Susan.
Audition of the Zeus
.
A friend and I were lucky enough just over a week ago to get to audition Susan's Zeus amplifier along with the rest of her system and I have to say we were pretty impressed with what we heard ...
Susan explained that the system did not have any esoteric, hi end, expensive components - just stuff that she happened to have at the time when she built the system.
Of course, it is always difficult to know what is contributing what in an unfamiliar system but the overall sound cannot be better that the weakest link and overall sound was VERY good.
Over the last 5 years or so I have listened to quite a few home systems of different friends. Many DIY, some bought. I have also auditioned some very expensive stuff at dealers and attended a couple of hi-fi shows.
Susan's system seemed to combine good balance of detail, clarity and dynamics along with a lovely fluidity that made it really easy to listen to. I regard this combination as very rare. The sound was also quite big and effortless.
I have heard beautiful sounding systems that sounded somewhat compressed. I have heard very detailed systems that sound somehow too analytical or dry or rough. Then there are systems that sound nice and soft but lack detail.
For me, Susan's system had a special combination of fluidity, detail and dynamics that I regard as the best I have heard to date. ( not bad considereing some of the systems mentioned above cost £50,000+ ).
I will be ordering my transformers soon and I am really looking forward to hearing a zeus amp in my system ( although realistically I think it will be mid January before this is realised ).
mike
.
A friend and I were lucky enough just over a week ago to get to audition Susan's Zeus amplifier along with the rest of her system and I have to say we were pretty impressed with what we heard ...
Susan explained that the system did not have any esoteric, hi end, expensive components - just stuff that she happened to have at the time when she built the system.
Of course, it is always difficult to know what is contributing what in an unfamiliar system but the overall sound cannot be better that the weakest link and overall sound was VERY good.
Over the last 5 years or so I have listened to quite a few home systems of different friends. Many DIY, some bought. I have also auditioned some very expensive stuff at dealers and attended a couple of hi-fi shows.
Susan's system seemed to combine good balance of detail, clarity and dynamics along with a lovely fluidity that made it really easy to listen to. I regard this combination as very rare. The sound was also quite big and effortless.
I have heard beautiful sounding systems that sounded somewhat compressed. I have heard very detailed systems that sound somehow too analytical or dry or rough. Then there are systems that sound nice and soft but lack detail.
For me, Susan's system had a special combination of fluidity, detail and dynamics that I regard as the best I have heard to date. ( not bad considereing some of the systems mentioned above cost £50,000+ ).
I will be ordering my transformers soon and I am really looking forward to hearing a zeus amp in my system ( although realistically I think it will be mid January before this is realised ).
mike
Re: Audition of the Zeus
Dear Mike,
Thank you for your kind comments.
The setup was with my prototype CD-ROM drive CD player which uses ECL differential connection for the audio serial data to the preamp's DACs (MC10H124 Quad TTL to MECL > Ribbon Cable > MC10H125 Quad MECL to TTL).
Burr Brown 20 bit DACs (I will put up some information on the preamp soon).
Differential preamp line output is with OP275 opamps.
Zeus monoblock amplifiers in 4:1 output (15 watts max) configuration.
Beyond the Box floor standing speakers.
Best wishes,
Susan.
Dear Mike,
Thank you for your kind comments.
mikelm said:.
A friend and I were lucky enough just over a week ago to get to audition Susan's Zeus amplifier along with the rest of her system and I have to say we were pretty impressed with what we heard ...
Susan explained that the system did not have any esoteric, hi end, expensive components - just stuff that she happened to have at the time when she built the system.
Of course, it is always difficult to know what is contributing what in an unfamiliar system but the overall sound cannot be better that the weakest link and overall sound was VERY good.
[snip]
For me, Susan's system had a special combination of fluidity, detail and dynamics that I regard as the best I have heard to date. ( not bad considereing some of the systems mentioned above cost £50,000+ ).
[snip]
mike
The setup was with my prototype CD-ROM drive CD player which uses ECL differential connection for the audio serial data to the preamp's DACs (MC10H124 Quad TTL to MECL > Ribbon Cable > MC10H125 Quad MECL to TTL).
Burr Brown 20 bit DACs (I will put up some information on the preamp soon).
Differential preamp line output is with OP275 opamps.
Zeus monoblock amplifiers in 4:1 output (15 watts max) configuration.
Beyond the Box floor standing speakers.
Best wishes,
Susan.
Website Updates
Dear All,
I have added a schematic for the STW34NB20 version to the "Building a Zeus" page:
http://www.susan-parker.co.uk/zeus-construction.htm
... and an intermodulation test to the 2SK1529 FFT test page.
http://www.susan-parker.co.uk/zeus-test-2sk1529-fft-1khz.htm
Still working on getting a definitive test set up configured
Best wishes,
Susan.
Dear All,
I have added a schematic for the STW34NB20 version to the "Building a Zeus" page:
http://www.susan-parker.co.uk/zeus-construction.htm
... and an intermodulation test to the 2SK1529 FFT test page.
http://www.susan-parker.co.uk/zeus-test-2sk1529-fft-1khz.htm
Still working on getting a definitive test set up configured
Best wishes,
Susan.
Re: Sowter made OP transformer bobbins
I don't know how I missed this post
Yesterday, I made up my mind to simply go ahead and order the Sowter transformers. I figured $250 US for the input and probably an equal amount or less for the outputs.
So, I spent the afternoon driving around Los Angeles returning a bunch of tools, etc. that I never used to Home Depot and other stores. Came home with enough cash for the inputs and maybe some extra for the outputs - then I re-read your post.
$750 US for all four transformers!
Looks like I will have to get the inputs now and wind my own output is this amp is ever going to see the light of day in my house.
Susan-Parker said:
I don't know how I missed this post
Yesterday, I made up my mind to simply go ahead and order the Sowter transformers. I figured $250 US for the input and probably an equal amount or less for the outputs.
So, I spent the afternoon driving around Los Angeles returning a bunch of tools, etc. that I never used to Home Depot and other stores. Came home with enough cash for the inputs and maybe some extra for the outputs - then I re-read your post.
$750 US for all four transformers!
Looks like I will have to get the inputs now and wind my own output is this amp is ever going to see the light of day in my house.
Re: Re: Sowter made OP transformer bobbins
Dear Darkmoebius,
Sorry that you got a fright. Unfortunately the UK pound is strong versus the US Dollar and this is not helping either.
If you buy the wound bobbins only, and get the laminations and frames separately you should be able to get a good saving and much lower shipping cost than buying fully assembled transformers.
Winding the output transformers oneself on a EI-120 split bobbin (for the multiple option version) is not difficult although a bit of patience and care is required to count turns and get the layers even for both sides.
Winding on a single chamber bobbin with four 1.0 mm wires for the simpler 2:1 only configuration is a walk in the park (honest).
You can also use the finer M2 or M3 laminations from Thomas & Skinner which should push the distortion levels down further.
Best wishes,
Susan.
Dear Darkmoebius,
Sorry that you got a fright. Unfortunately the UK pound is strong versus the US Dollar and this is not helping either.
darkmoebius said:
I don't know how I missed this post
Yesterday, I made up my mind to simply go ahead and order the Sowter transformers. I figured $250 US for the input and probably an equal amount or less for the outputs.
So, I spent the afternoon driving around Los Angeles returning a bunch of tools, etc. that I never used to Home Depot and other stores. Came home with enough cash for the inputs and maybe some extra for the outputs - then I re-read your post.
$750 US for all four transformers!
Looks like I will have to get the inputs now and wind my own output is this amp is ever going to see the light of day in my house.
If you buy the wound bobbins only, and get the laminations and frames separately you should be able to get a good saving and much lower shipping cost than buying fully assembled transformers.
Winding the output transformers oneself on a EI-120 split bobbin (for the multiple option version) is not difficult although a bit of patience and care is required to count turns and get the layers even for both sides.
Winding on a single chamber bobbin with four 1.0 mm wires for the simpler 2:1 only configuration is a walk in the park (honest).
You can also use the finer M2 or M3 laminations from Thomas & Skinner which should push the distortion levels down further.
Best wishes,
Susan.
Re: Sowter made OP transformer bobbins
Hi Dave,
Um, I guess.
I am doing my best to try to recommend components that are as affordable as possible. But unfortunately transformers and heatsinks are expensive to buy.
Here's a quick sketch of one way to build the amp:
Mono-block Amplifier with separate PSU in its own steel enclosure (this cuts down on the magnetic field radiation/pickup).
The amp is designed to be tall and not deep so as to sit behind or to one side of the speaker it is driving.
Heatsink (N.B. SK157 profile) 300 x 200 x 80 mm with a 300 x 150 x 80 mm steel chassis which sits in front of and at the bottom of the heatsink. The output transformer sits on top of the steel chassis, the input transformer is inside and thus screened from electrical and magnetic fields (including the output transformer's).
The PSU is in a separate 300 x 200 x 80 mm enclosure and sits under or to one side of the amplifier. Power connection is a (short) loop of cable with 4 pin XLR connectors.
I did a quick "back of envelope" costing as to how much each amp costs and buying all new from distribution is about UKP 550 per monoblock!
To be economically viable for me to build (i.e. putting aside my consultancy work and building audio kit instead) I would have to charge UKP 1495 (+ sales tax in the EU) each if I was building them for sale - and that would be "special direct 'dealer' price". Retail in the high street would end up being something like UKP 2495 each.
So UKP 4990 for a stereo pair. That's just for power output stage as well. Still need a preamp/line driver.
As in most things custom bespoke and just building in twos or sixes is expensive.
Its quite scary how quickly the costs mount up.
Best wishes,
Susan.
Hi Dave,
planet10 said:
Um, I guess.
I am doing my best to try to recommend components that are as affordable as possible. But unfortunately transformers and heatsinks are expensive to buy.
Here's a quick sketch of one way to build the amp:
Mono-block Amplifier with separate PSU in its own steel enclosure (this cuts down on the magnetic field radiation/pickup).
The amp is designed to be tall and not deep so as to sit behind or to one side of the speaker it is driving.
Heatsink (N.B. SK157 profile) 300 x 200 x 80 mm with a 300 x 150 x 80 mm steel chassis which sits in front of and at the bottom of the heatsink. The output transformer sits on top of the steel chassis, the input transformer is inside and thus screened from electrical and magnetic fields (including the output transformer's).
The PSU is in a separate 300 x 200 x 80 mm enclosure and sits under or to one side of the amplifier. Power connection is a (short) loop of cable with 4 pin XLR connectors.
I did a quick "back of envelope" costing as to how much each amp costs and buying all new from distribution is about UKP 550 per monoblock!
To be economically viable for me to build (i.e. putting aside my consultancy work and building audio kit instead) I would have to charge UKP 1495 (+ sales tax in the EU) each if I was building them for sale - and that would be "special direct 'dealer' price". Retail in the high street would end up being something like UKP 2495 each.
So UKP 4990 for a stereo pair. That's just for power output stage as well. Still need a preamp/line driver.
As in most things custom bespoke and just building in twos or sixes is expensive.
Its quite scary how quickly the costs mount up.
Best wishes,
Susan.
Rollin' your own....
Aaaaah, a decent shock every once in a while is good for the circulation
In reality, your amps are no more expensive to build than a lot of the SE & PP tube amps I was considering - especially the 300B variants. In that case, I would still have to buy the driver/output tubes and the the output and interstage transformers. Filament transformers, cockets, designers capacitors, PS filtering components, etc.
The chassis and connector costs would be the same no matter what topolgy, so in that light your amps are reasonable. Although, those SK158 heatsinks are another shocker
$270 EUR/$360 US.
Is it also possible to buy the bobbins for the input transformer also? If so, what EI and stack size is the bobbin/laminations?
That might help bring the total purchase within my price range.
Patience & time are two things that I have an abundance of, as compared to money. I could easily construct a reliable hand-crank winding system w/ a turns counter.
I was trying to work things out in my head last night - here's a partial list of needs:
(2) EI-120 x 50mm/2" two-chamber bobbins
(2) sets of EI-120 x 50mm M2 .007" Super-Orthosil laminations (Thomas & Skinner)
(?) 0.8mm enameled magnet wire.
(2) sets of EI-120 transformer frames
(8) non-magnetic lamination screws & bolts
The winding geometry has me a little confused. For the Sowter 9840 type output, is the winding geometry like your example "Version 2 Windings" [/B][/QUOTE]here?
In that example, I assume for each chamber that we first wind all 12 layers(2 wires) of the primary around the bobbin first, then 6 layers of the secondary(2 wires) - loop out for midpoint taps - then continue the final 6 layers of the secondary. No insulation or paper between windings, except between primary and secondary.
Although, your "start/finish" numbers make me think that you suggest interleaving the primary and seondary. Is this right?
And those in charge tell us this is good for Americans
May be good for exports, but sucks for importing.
Susan-Parker said:
Aaaaah, a decent shock every once in a while is good for the circulation
In reality, your amps are no more expensive to build than a lot of the SE & PP tube amps I was considering - especially the 300B variants. In that case, I would still have to buy the driver/output tubes and the the output and interstage transformers. Filament transformers, cockets, designers capacitors, PS filtering components, etc.
The chassis and connector costs would be the same no matter what topolgy, so in that light your amps are reasonable. Although, those SK158 heatsinks are another shocker
$270 EUR/$360 US.Is it also possible to buy the bobbins for the input transformer also? If so, what EI and stack size is the bobbin/laminations?
That might help bring the total purchase within my price range.
Patience & time are two things that I have an abundance of, as compared to money. I could easily construct a reliable hand-crank winding system w/ a turns counter.
I was trying to work things out in my head last night - here's a partial list of needs:
(2) EI-120 x 50mm/2" two-chamber bobbins
(2) sets of EI-120 x 50mm M2 .007" Super-Orthosil laminations (Thomas & Skinner)
(?) 0.8mm enameled magnet wire.
(2) sets of EI-120 transformer frames
(8) non-magnetic lamination screws & bolts
The winding geometry has me a little confused. For the Sowter 9840 type output, is the winding geometry like your example "Version 2 Windings" [/B][/QUOTE]here?
In that example, I assume for each chamber that we first wind all 12 layers(2 wires) of the primary around the bobbin first, then 6 layers of the secondary(2 wires) - loop out for midpoint taps - then continue the final 6 layers of the secondary. No insulation or paper between windings, except between primary and secondary.
Although, your "start/finish" numbers make me think that you suggest interleaving the primary and seondary. Is this right?
planet10 said:
And those in charge tell us this is good for Americans
May be good for exports, but sucks for importing.
Hey Enoch!!!
You're only a few minutes away from me in San Pedro. Nice to know there's another DIY'er in the area.
Yeah, they may have that on us but, there is one thing they can't ruin - it is currently 75-80 degrees (F) here at the beach in sunny Southern California. I can look out my home office window and see all of Catalina Island and the Channel Islands to the north. Clear with Santa Ana conditions.
No sign of Winter here, at all.
In celebration, I'm going to blow off all work today and take the dogs a few hundred yards down the hill for a hike through the canyons along the cliffs overlooking the Pacific ocean. May even hike down to the tide pools and let the dogs splash about.
Take that, all you East Coasters, Euro's, Brits, etc.
You're only a few minutes away from me in San Pedro. Nice to know there's another DIY'er in the area.
enochRoot said:ie: it's good for big business (who post record sales in times of a weak dollar), and bad for consumers...
Yeah, they may have that on us but, there is one thing they can't ruin - it is currently 75-80 degrees (F) here at the beach in sunny Southern California. I can look out my home office window and see all of Catalina Island and the Channel Islands to the north. Clear with Santa Ana conditions.
No sign of Winter here, at all.
In celebration, I'm going to blow off all work today and take the dogs a few hundred yards down the hill for a hike through the canyons along the cliffs overlooking the Pacific ocean. May even hike down to the tide pools and let the dogs splash about.
Take that, all you East Coasters, Euro's, Brits, etc.