Transformer won't be a problem.
I used to work for a custom transformer manufacturer.
So should be able to get whatever I need at a better price.
Main reason for wanting a 'basic' supply is to cope with user abuse.
It'll cop a bit a imagine.
He has a crude regulated 15a (cont) supply that I've repaired three times now (in three years).
Partly due to poor design.
If I ever get an answer out of him, I'll either go basic bridge and filter, or overkill regulated with as little excess voltage as possible
I used to work for a custom transformer manufacturer.
So should be able to get whatever I need at a better price.
Main reason for wanting a 'basic' supply is to cope with user abuse.
It'll cop a bit a imagine.
He has a crude regulated 15a (cont) supply that I've repaired three times now (in three years).
Partly due to poor design.
If I ever get an answer out of him, I'll either go basic bridge and filter, or overkill regulated with as little excess voltage as possible
He hasn't given a yes/no yet (what a suprise) so I'm classing this as a 'what if' design at the moment.
So, In my mind I'm thinking of;
Transformer 240vac 1500va with two 12vac 25amp secondaries.
(Or would two seperate 700va trans be better ? heat disipation at power ?)
Each feeds a 35amp 400v bridge.
Pair of 10,000uF 25vdc caps.
Should give around 17vdc filtered.
Final stage of a lm338k reg driving 10x 2n3771
Final output of 13vdc @ 50amps.....
Thoughts ?
What have I missed ?
How can it be bettered ?
So, In my mind I'm thinking of;
Transformer 240vac 1500va with two 12vac 25amp secondaries.
(Or would two seperate 700va trans be better ? heat disipation at power ?)
Each feeds a 35amp 400v bridge.
Pair of 10,000uF 25vdc caps.
Should give around 17vdc filtered.
Final stage of a lm338k reg driving 10x 2n3771
Final output of 13vdc @ 50amps.....
Thoughts ?
What have I missed ?
How can it be bettered ?
star882 said:
That's exactly what I did for my 400W subwoofer amp.
Old page,hasn't been updated,etc,etc..but the basics are all there.
http://www.users.qwest.net/~ptaylor/Electronics/MOTpowersupply/MOTPSpage.html
Use big beefy rectifiers,and lots of capacitance.
Hi,
1500VA 25+25Vac is going to give 30Aac from each secondary.
This will require a minimum of 9sqmm and more likely 10sqmm of wire for that current.
The secondaries will NOT be single solid core.
They will be bifillar or trifillar or maybe even quad fillar wound.
Separate each of the separate wires and rectify each secondary winding and after the heatsinked rectifiers parallel them for a single polarity 30Adc supply. For this level of current you will need a lot more than 10mF of smoothing to keep the ripple low enough to avoid dropout in the regulator.
Probably at least 40mF, but a scope will tell you how badly the smoothing is performing (monitor Vdc before and after the regulator).
1500VA 25+25Vac is going to give 30Aac from each secondary.
This will require a minimum of 9sqmm and more likely 10sqmm of wire for that current.
The secondaries will NOT be single solid core.
They will be bifillar or trifillar or maybe even quad fillar wound.
Separate each of the separate wires and rectify each secondary winding and after the heatsinked rectifiers parallel them for a single polarity 30Adc supply. For this level of current you will need a lot more than 10mF of smoothing to keep the ripple low enough to avoid dropout in the regulator.
Probably at least 40mF, but a scope will tell you how badly the smoothing is performing (monitor Vdc before and after the regulator).
PSA1225 from GME.
cheaper than building one. 25A continuous, 35 amp peak.
http://www.gme.net.au/land/power_products.php
Use two and split the load into two separate circuits.
cheaper than building one. 25A continuous, 35 amp peak.
http://www.gme.net.au/land/power_products.php
Use two and split the load into two separate circuits.
AndrewT.
Ta.
I'm just doing very rough numbers/ideas at the moment.
I'm aiming for around 17vdc filtered (before regulation section) to try and keep heat down in the reg section, hence why I'm thinking of 12vac secondaries.
I've just found some really nice bridges that should work well, 50amp 600v. and there cheap ~$4 each.
So I should aim for around 1400watts for the trans ?
If this goes ahead I'll let my freinds at the transformer winders work out the exact details.
Guy that this is for is actually starting to sound interested in proceeding.
Planning on a steel case and will have the bridges bolted to that.
I don't believe it will see big current draws often so this hopefully will be enough.
40mF Alright will have to allow for a bit more in that area.
Won't be a problem.
OzMikeH,
Ta. shall have a browse.
Don't spose you know what the PSA1225 is worth ?
If not that s fine, I'll give em a yell tommorow when I get a chance....
I'm estimating that this whole monster will be around $500 depending on transformer cost (~$300)
Ta.
I'm just doing very rough numbers/ideas at the moment.
I'm aiming for around 17vdc filtered (before regulation section) to try and keep heat down in the reg section, hence why I'm thinking of 12vac secondaries.
I've just found some really nice bridges that should work well, 50amp 600v. and there cheap ~$4 each.
So I should aim for around 1400watts for the trans ?
If this goes ahead I'll let my freinds at the transformer winders work out the exact details.
Guy that this is for is actually starting to sound interested in proceeding.
Planning on a steel case and will have the bridges bolted to that.
I don't believe it will see big current draws often so this hopefully will be enough.
40mF Alright will have to allow for a bit more in that area.
Won't be a problem.
OzMikeH,
Ta. shall have a browse.
Don't spose you know what the PSA1225 is worth ?
If not that s fine, I'll give em a yell tommorow when I get a chance....
I'm estimating that this whole monster will be around $500 depending on transformer cost (~$300)
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