just when i thought i understand it .....
so looking at this schematic http://home.student.utwente.nl/f.s.bouwman/audio/images/invertedLM3875.gif
i see that the schematic gives 2 grounds and one V+ and one V- .. am i correct?
but .. the schematic uses both of the secondaries? which confuses me ..
seems to work for one channel, what happens for the second channel???
or is that for use with two torroids? (i'm planning on having one 400VA)
so looking at this schematic http://home.student.utwente.nl/f.s.bouwman/audio/images/invertedLM3875.gif
i see that the schematic gives 2 grounds and one V+ and one V- .. am i correct?
but .. the schematic uses both of the secondaries? which confuses me ..
seems to work for one channel, what happens for the second channel???
or is that for use with two torroids? (i'm planning on having one 400VA)
It's using one transformer for both channels and this is exactly what I've been doing. I only use separate wires from PS to ea. channel, so that's why it's 8 of them.
oh, so you mean looking at the previous power supply i just branch V+, V- and the two grounds (i guess you could call it y-splitting?) and then run each through a separate wire to the amps?
btw .. another comment
i got some 3A/4A/6 1/4A fuses today .. they didn't carry 7A
i suppose i should try 3A first, then move up if need be?
btw .. another comment
i got some 3A/4A/6 1/4A fuses today .. they didn't carry 7A
i suppose i should try 3A first, then move up if need be?
I don't think 3A is enough with 400VA toroid, start with 4 A. And ground wires are run ea. from a separate bridge, to make it clear.
yeah, now i understand it!!!
amazing .. took me a while, but hey 🙂
gotta learn somehow ..
thank you .. i'll be sure to come back for more help when i get all the parts 🙂
amazing .. took me a while, but hey 🙂
gotta learn somehow ..
thank you .. i'll be sure to come back for more help when i get all the parts 🙂
ahh!
just now i ran across the correct PS/amp schematics in the GC thread ..
the PS supply is made as i thought so 🙂
just now i ran across the correct PS/amp schematics in the GC thread ..
the PS supply is made as i thought so 🙂
oh, one more q 🙂
digikey has 2 types of 3875's available
LM3875T and LM3875TF .. which of the 2 should i get? and what's the difference?
digikey has 2 types of 3875's available
LM3875T and LM3875TF .. which of the 2 should i get? and what's the difference?
I think TF is isolated, so you don't need a pad when you place it on a heat sink.
I always use non isolated, because I believe that by using better insulating pads I can improve heat dissipation and I noticed that a pad has slight influence on a sound. I like to use aluminum oxide pads and if not for European guys, beryllium oxide too😉
I always use non isolated, because I believe that by using better insulating pads I can improve heat dissipation and I noticed that a pad has slight influence on a sound. I like to use aluminum oxide pads and if not for European guys, beryllium oxide too😉
allright 🙂
i think i saw active electronics carry the insulation pads when i was there earlier today .. they don't carry LM3875s 🙁
i think i saw active electronics carry the insulation pads when i was there earlier today .. they don't carry LM3875s 🙁
Ok,
Just got back home from work .. long day 🙁
decided to take another look at the power supply .. so i decided maybe i'll apply what i've learned so far (the little i did), use someone else's PS scheme (can't remember whose .. posted a link earlier) .. and this is what i came up with
Does this look good to you Peter? (Or someone else?) Or am I missing something?
Just got back home from work .. long day 🙁
decided to take another look at the power supply .. so i decided maybe i'll apply what i've learned so far (the little i did), use someone else's PS scheme (can't remember whose .. posted a link earlier) .. and this is what i came up with
Does this look good to you Peter? (Or someone else?) Or am I missing something?
Attachments
It looks good. If you shop at active you might get MUR860 diodes(or MSR860, but I don't think they carry them), because they sound pretty good when comparing to other types.
I'm just about to place an order for MUR1520 diodes from digikey.
Oh yeah, for the diodes, do you use a pcb to connect them? (Like a pre-drilled one)? Or can I (or do you) connect them p2p style?
Oh yeah, for the diodes, do you use a pcb to connect them? (Like a pre-drilled one)? Or can I (or do you) connect them p2p style?
Peter Daniel said:
Can I get it from Digikey? I checked their catalog, but I don't seem to find the one with the size of LM3875. Do you have any special source? Either aluminum oxide or beryllium oxide is fine with me. I'm not an European. 🙂
peter recommended at some point in time (and earlier in this thread) to use 2 separate grounds, which are not connected until star ground in the amps themselves ..
well, i suppose i'm getting everything pretty soon
still have to order the resistors/4.7uF cap from partsconnexion and the torroid from plitron, but the digikey order is placed and it went through .. should come wednesday 🙂
so far, my cost is $250 not including the price of wire/chassis and shipping for the torroid
i'm making a spreadsheet which will hopefully help someone like me in the future 🙂
i know there's already one made which helped ME lots!
but hey, some more info never hurt anyone, right?
So i figure the total project cost will be $300 .. but that's because i got some extra parts (about $20-$30 worth of) .. so still $300 for an amp that'll hopefully be MUCH better than the crappy receiver i have
not a bad deal i'd say 🙂
but its about time i get to sleep .. can't think about much other than the amp right now .. quite excited!
i already have some neat designs for the case in my head .. and some new project ideas when i get some money! 🙂
well, i suppose i'm getting everything pretty soon
still have to order the resistors/4.7uF cap from partsconnexion and the torroid from plitron, but the digikey order is placed and it went through .. should come wednesday 🙂
so far, my cost is $250 not including the price of wire/chassis and shipping for the torroid
i'm making a spreadsheet which will hopefully help someone like me in the future 🙂
i know there's already one made which helped ME lots!
but hey, some more info never hurt anyone, right?
So i figure the total project cost will be $300 .. but that's because i got some extra parts (about $20-$30 worth of) .. so still $300 for an amp that'll hopefully be MUCH better than the crappy receiver i have
not a bad deal i'd say 🙂
but its about time i get to sleep .. can't think about much other than the amp right now .. quite excited!
i already have some neat designs for the case in my head .. and some new project ideas when i get some money! 🙂
JAZZ2250 said:
I'm using TO-247 size pads. They are slightly smaller than the chip, but it works fine and I never had a problem. Didg-Key doesn't carry them. Check this thread: http://www.diyaudio.com/forums/showthread.php?s=&postid=148888#post148888
For bridges, I'm using proto boards and p2p technique.
elizard,
I have a 225 va, 18v secondaries Plitron transformer sitting here, waiting to be used. I'm got too much on the go right now. I paid $35 USD for it plus shipping from Vancouver (about half the cost of direct from Plitron). If you are interested let me know offline and we can arrange to meet. I'd like to have a listen to the finished amp though 🙂)
Steve.
I have a 225 va, 18v secondaries Plitron transformer sitting here, waiting to be used. I'm got too much on the go right now. I paid $35 USD for it plus shipping from Vancouver (about half the cost of direct from Plitron). If you are interested let me know offline and we can arrange to meet. I'd like to have a listen to the finished amp though 🙂)
Steve.
naw .. i'm gonna go for the 400VA one
its $72CAD .. plus that way i can use it for another project if i want
but once i've built it, we could probably arrange a meet so you can hear it 🙂
gonna be a few weeks first
Peter: I'm gonna contact Active and see if they have it in stock (seeing you have it in an active packaging bag)
oh and spind, you're only the 2nd person i saw on this message board from winnipeg
i'm sure there's more, but only 2 that i saw so far 🙂
nice to see some locals too .. sadly there isn't more 🙁
its $72CAD .. plus that way i can use it for another project if i want
but once i've built it, we could probably arrange a meet so you can hear it 🙂
gonna be a few weeks first
Peter: I'm gonna contact Active and see if they have it in stock (seeing you have it in an active packaging bag)
oh and spind, you're only the 2nd person i saw on this message board from winnipeg
i'm sure there's more, but only 2 that i saw so far 🙂
nice to see some locals too .. sadly there isn't more 🙁
mbe it bears repeating -- start with an old HP power supply
if you want to build an inexpensive high end amplifier -- start with one of the older HP, Kepco, Fluke, Lambda, Systron Donner programmable analog power supplies -- a supply rated for 100 watts is rated for 100 watts industrial, not 100 watts by Pioneer or Sony -- these supplies are used by GE, Boeing, GM, etc. for continuous testing. Because many of these units used separate binary encoders (often lost in the shuffle) they can be had for $10 to $30. My last acquisition was an HP6130 for $19 just this week.
You get a first class chasis, first class power interconnects, fusing relays, meters -- and a big butt transformer (sometimes 2). As many of these power supplies are amplifiers in reality, there is plenty of room to modify and add the guts of a very nice modern amp inside.
if you want to build an inexpensive high end amplifier -- start with one of the older HP, Kepco, Fluke, Lambda, Systron Donner programmable analog power supplies -- a supply rated for 100 watts is rated for 100 watts industrial, not 100 watts by Pioneer or Sony -- these supplies are used by GE, Boeing, GM, etc. for continuous testing. Because many of these units used separate binary encoders (often lost in the shuffle) they can be had for $10 to $30. My last acquisition was an HP6130 for $19 just this week.
You get a first class chasis, first class power interconnects, fusing relays, meters -- and a big butt transformer (sometimes 2). As many of these power supplies are amplifiers in reality, there is plenty of room to modify and add the guts of a very nice modern amp inside.
Attachments
well .. digikey order went through, expecting it tomorrow
just called plitron, and its 4-5 weeks .. man, that'll be quite some downtime seeing i sell the crap receiver i have in in a couple weeks ..
still have to order from partsconnexion .. will do that tomorrow ..
gonna go and try to find some cheap 5mm or 1/4" aluminum today .. maybe go as thick as 1/2" ..
but its all good .. thank you for all the support, i'm sure i'll need more in weeks to come 🙂
maybe i'll build the cables tomorrow night .. or maybe i'll just study for the exams!!! like i should 🙂
thank you all once again
just called plitron, and its 4-5 weeks .. man, that'll be quite some downtime seeing i sell the crap receiver i have in in a couple weeks ..
still have to order from partsconnexion .. will do that tomorrow ..
gonna go and try to find some cheap 5mm or 1/4" aluminum today .. maybe go as thick as 1/2" ..
but its all good .. thank you for all the support, i'm sure i'll need more in weeks to come 🙂
maybe i'll build the cables tomorrow night .. or maybe i'll just study for the exams!!! like i should 🙂
thank you all once again
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