static electricity season
The house I live in now has allot of static electricity in it due to the winter dry air and electric furnace. Should I wait until end March or April to pair together the MOSFETs ? The air will be damp again in the spring and the static disappears, dose anyone have an idea about this or just waiting is the best ?
Thank You
scatterbrain001
The house I live in now has allot of static electricity in it due to the winter dry air and electric furnace. Should I wait until end March or April to pair together the MOSFETs ? The air will be damp again in the spring and the static disappears, dose anyone have an idea about this or just waiting is the best ?
Thank You
scatterbrain001
if that's so much worry to you - make DIY working area - kitchen Al foil as working sheet - grounded , thin wire clipped to your wedding ring and grounded ;
unpack parts on foil and work
if you aren't married - then you should wait 'till damp
( nota bene - there's nothing more important than peace of mind ..... so do that even if I can't see how you can kill your mosfets even in those conditions )
unpack parts on foil and work
if you aren't married - then you should wait 'till damp
( nota bene - there's nothing more important than peace of mind ..... so do that even if I can't see how you can kill your mosfets even in those conditions )
As I am making 108db sensitive horn wont be needinh to build X version.
Has anyone used these toroids from tortech
300VA Toroid Transformer
I only need 25 watts so these look sufficient to me.
Has anyone used these toroids from tortech
300VA Toroid Transformer
I only need 25 watts so these look sufficient to me.
Fuse protection
Hi, I have not looked at this Thred for a while because I had to allocate my finances to other projects, but now I am back and am ready to purchase the finnal components to build two mono Aleph J-X amps.
Right now I aam looking for information on what value of fuses should be used for:
1. each AC line into transformer
2. each of the four transformer(600VAC with18+18 secondary) output cables
3. each of the +&- outputs from the two bridge rectifiers used
per mono channel, thats one bridge rectifier for each rail (positive & negative)
Thank You For Your Help
Ian Scaiff
(scatterbrain001)
Hi, I have not looked at this Thred for a while because I had to allocate my finances to other projects, but now I am back and am ready to purchase the finnal components to build two mono Aleph J-X amps.
Right now I aam looking for information on what value of fuses should be used for:
1. each AC line into transformer
2. each of the four transformer(600VAC with18+18 secondary) output cables
3. each of the +&- outputs from the two bridge rectifiers used
per mono channel, thats one bridge rectifier for each rail (positive & negative)
Thank You For Your Help
Ian Scaiff
(scatterbrain001)
Last edited:
You only need to fuse the hot mains lead. The fuse should be the first thing connected to the hot lead when it enters the case - before the power switch and inrush limiting. With a 600 VA transformer using a 50% overload on 120V mains you want around a 7.5A fuse, depending on your inrush current limiting scheme. You may want to use a slow blow fuse.
No need to directly fuse the secondaries, just connect them to the bridges. If you have a bridge problem a properly sized mains fuse will blow. The same argument could be made for not fusing the rails. A problem arises when you have to size the mains fuse unreasonably large to survive the startup inrush of the the transformer and main filter caps. The safest way is to fuse the rails.
If you choose to fuse the rails individually, then choose something like 2.5 x the bias current you have running. If you bias at 2A, choose a 5A fuse and so on. This will allow you to protect against catastrophe and safely pass the maximum current that the amp can draw.
No need to directly fuse the secondaries, just connect them to the bridges. If you have a bridge problem a properly sized mains fuse will blow. The same argument could be made for not fusing the rails. A problem arises when you have to size the mains fuse unreasonably large to survive the startup inrush of the the transformer and main filter caps. The safest way is to fuse the rails.
If you choose to fuse the rails individually, then choose something like 2.5 x the bias current you have running. If you bias at 2A, choose a 5A fuse and so on. This will allow you to protect against catastrophe and safely pass the maximum current that the amp can draw.
purchasing components
I lost my Internet Explorer Favorites for the period I was looking over a internet site recomended by you for purchasing electronic components and other stuff, I should remember his address but I am drawing a blank, could you please refresh my memory because I need my power supply heat sinks and other stuff from him ?
Thank You
Ian
I lost my Internet Explorer Favorites for the period I was looking over a internet site recomended by you for purchasing electronic components and other stuff, I should remember his address but I am drawing a blank, could you please refresh my memory because I need my power supply heat sinks and other stuff from him ?
Thank You
Ian
Apex Jr.Home Page is my favorite surplus place. Call Steve if you don't see what you want on the web - he often has stuff that hasn't made the website.
full schema required...
Dear all:
I plan to order Peter's aleph-jx pcb, and I've read all post about aleph-jx in this forum.
But I still confuse about the "full aleph-jx schema".
I know aj-x front end schema in this thread.
But I don't understand how this front-end combine to the original aleph-j's schema.
And what's the exact resistor & capacitor's value ?
I've calculate base on AXE-1.2.xls.
It shows that if I want to build a 50w aleph-jx , the rails voltage should be +-17v.
But how many output mosfets should use in this project ?
Is IRFP240 suitable in this low voltage (+-17v) circuit ?
Regards,
Dear all:
I plan to order Peter's aleph-jx pcb, and I've read all post about aleph-jx in this forum.
But I still confuse about the "full aleph-jx schema".
I know aj-x front end schema in this thread.
But I don't understand how this front-end combine to the original aleph-j's schema.
And what's the exact resistor & capacitor's value ?
I've calculate base on AXE-1.2.xls.
It shows that if I want to build a 50w aleph-jx , the rails voltage should be +-17v.
But how many output mosfets should use in this project ?
Is IRFP240 suitable in this low voltage (+-17v) circuit ?
Regards,
Hi Scrazy,
I agree with Bill, this project may put you off DIY if you cant pull it off. You can try an aleph J or if you like X topology, Euval is making circuit boards for an F5-X.
If you really need an alephj-X look at your spreadsheet again. You need to choose how many fets you use in multiples of 4. Four should be good for 50 watts. If you increase the bias, look at the dissipation per fet. Ideally it shouldn't really exceed 35-40 watts per fet. But its dependant on teh heat, you need to work out how much sinking you need o keep temprature to around 55-60 degrees. So if you want 7 amps bias, I expect you will want more than 4 fets, probably 12.
For low rails like yours the irfp240 will work, if you have them use them. Ideally they should be very closely matched. If you are buying fets try our forum member (forget his name) Tech DIY Company Store
Good luck, but this one is not an easy project and needs some tweaking.
One thing I've thought about, what is the actual advantage of X-ing the Aleph J?
If I've understood correctly it becomes a completely different amp, but as far as I've looked none has described the sound of the amp. Does it still sound like an Aleph J in areas or is it completely different?
What I basically wonder is if there are sonic advantages with the design are or if it's a case of "it's hard to build, so I want to build it just because I can."?
// Olle
If I've understood correctly it becomes a completely different amp, but as far as I've looked none has described the sound of the amp. Does it still sound like an Aleph J in areas or is it completely different?
What I basically wonder is if there are sonic advantages with the design are or if it's a case of "it's hard to build, so I want to build it just because I can."?
// Olle
Hi Eric,
If you've built an Aleph before and understand their operation then you should be able to pull it off. It's a bridged amp with quite a bit of interaction between the two halves, and the interaction somewhat defeats the stability of the individual Aleph circuits. Parts matching becomes much more important, maybe to the point of being anal, but a 50 watt amp should be easily doable for you.
Best, Bill
If you've built an Aleph before and understand their operation then you should be able to pull it off. It's a bridged amp with quite a bit of interaction between the two halves, and the interaction somewhat defeats the stability of the individual Aleph circuits. Parts matching becomes much more important, maybe to the point of being anal, but a 50 watt amp should be easily doable for you.
Best, Bill
The Master gave his description in one of his writeups, chocolate and peanut butter.
X-ing takes it from SE to push-pull so it would be quite different. Personally, I started one a couple years ago but talked myself out of finishing it. I have the chassis, maybe this year. I like my Js.
mounting IRFP240s electrical insulators
Do the IRFP240s need to be electrically insulated from the heatsink ? I have purchased mica insulators before I did any reading on it, is it worth while buying aluminum oxide insulators, or beryllium oxide insulators, however I have not found out where to purchase some beryllium oxide insulators yet.
Thank You all for your help.
Do the IRFP240s need to be electrically insulated from the heatsink ? I have purchased mica insulators before I did any reading on it, is it worth while buying aluminum oxide insulators, or beryllium oxide insulators, however I have not found out where to purchase some beryllium oxide insulators yet.
Thank You all for your help.