VDC to VAC
If you need 32 VDC +/- that is a PD of 64 VDC to calculate AC required from the secondary of a transformer it would be (64 x 1.414) / 2 = 45 VAC. That is two secondaries at 45 VAC or 90 VAC with a CT
Anthony
If you need 32 VDC +/- that is a PD of 64 VDC to calculate AC required from the secondary of a transformer it would be (64 x 1.414) / 2 = 45 VAC. That is two secondaries at 45 VAC or 90 VAC with a CT
Anthony
Re: VDC to VAC
Nelson Pass recommends 1.25 multiplier as it better renders real life situation.
Coulomb said:
Nelson Pass recommends 1.25 multiplier as it better renders real life situation.
Well If Nelson is listening that may be true with most transformers but with Toroidals the effeciency is drammatically increased and a figure closer to the theoretical can be used effectively. I mean not that I know much about this, I only design AC systems as a part time business for studios, Home Theatres and medical companies. 🙂
No disrespect intended Mr. Pass, I am sure in your day the old clunker H frame iron core beasts were terribly ineffcient. 🙂 🙂 🙂
Your Fan
Anthony
No disrespect intended Mr. Pass, I am sure in your day the old clunker H frame iron core beasts were terribly ineffcient. 🙂 🙂 🙂
Your Fan
Anthony
Coulomb
What is the deal with tweaking a 1.5kVA toroid with 60-0-60 secondaries to a 45-0-45 value, can it be done and more importantly, is it practical?
What is the deal with tweaking a 1.5kVA toroid with 60-0-60 secondaries to a 45-0-45 value, can it be done and more importantly, is it practical?
To get the 45v+- instead of 60v +- why not use a bucking transformer. That is a transformer with a 25v ac secondary.
By wiring this secondary in seriese with the ac input but out
of phase the main transformer will look at about 90v ac. So the
dc from your bridge and filter caps should be about 45v +-. Or
use a choke input filter.
Regards, bob12345678
By wiring this secondary in seriese with the ac input but out
of phase the main transformer will look at about 90v ac. So the
dc from your bridge and filter caps should be about 45v +-. Or
use a choke input filter.
Regards, bob12345678
Hi Nania,
The problem is you just have the wrong transformer for what you want to do.🙁
1.) If you use just caps for the power supply with the 60-0-60 transformer, you'll get 80+VDC rails.
2.) If you manage to tweak it to 45-0-45 and use just caps you'll get 60+VDC rails
3.) If you add an inductor between the caps in the power supply of #1 above, you'll get about 54VDC rails
So far, in 1, 2, and 3 above, the 40VDC caps you have will not work because their working voltage is too low.😡
Probably the best thing you could do is sell this transformer and get one that gives you the correct rail voltages.🙄
Sorry for you,
Rodd Yamashita
The problem is you just have the wrong transformer for what you want to do.🙁
1.) If you use just caps for the power supply with the 60-0-60 transformer, you'll get 80+VDC rails.
2.) If you manage to tweak it to 45-0-45 and use just caps you'll get 60+VDC rails
3.) If you add an inductor between the caps in the power supply of #1 above, you'll get about 54VDC rails
So far, in 1, 2, and 3 above, the 40VDC caps you have will not work because their working voltage is too low.😡
Probably the best thing you could do is sell this transformer and get one that gives you the correct rail voltages.🙄
Sorry for you,
Rodd Yamashita
bob12345678
I was hoping for a more elegant solution so adding additional transformers is undesirable to me but thanks for your reply.
roddyama
What kind of Pass monoblocks can I build with these 40V caps? Having to sell the toroids will hurt but so would selling the caps so I need to make a plan. I was hoping to create a power section that could supply all the "X" versions of the Pass aleph and Zen models. I am getting the sense that this may not be possible. You probably noted the parts I have so what are my options?
I was hoping for a more elegant solution so adding additional transformers is undesirable to me but thanks for your reply.
roddyama
What kind of Pass monoblocks can I build with these 40V caps? Having to sell the toroids will hurt but so would selling the caps so I need to make a plan. I was hoping to create a power section that could supply all the "X" versions of the Pass aleph and Zen models. I am getting the sense that this may not be possible. You probably noted the parts I have so what are my options?
Nania,
I had this whole post finished and my ****ing computer took a Sh*t (Bill, how's that?) $*)@&*)#^%.
Anyway, The Aleph 5 has 32VDC rails which requires about a 24-0-24 transformer and give you 60wpc with the right bias. The Zen (The original configuration) when you use 32VDC rails will put out (I believe) about 1/4th the power at about 15wpc, but SE output.
I'm not too familiar with the x-amps or the AlephX, but they will be more efficient. I did see on the Pass Lab site that the 150X has 32VDC rails. The AlephX is probably what you want. Check out this thread. It'll take a lot of reading, but I think you'll find what your looking for.
http://www.diyaudio.com/forums/showthread.php?s=&threadid=3748
Get out the bi-focals,
Rodd Yamashita
I had this whole post finished and my ****ing computer took a Sh*t (Bill, how's that?) $*)@&*)#^%.
Anyway, The Aleph 5 has 32VDC rails which requires about a 24-0-24 transformer and give you 60wpc with the right bias. The Zen (The original configuration) when you use 32VDC rails will put out (I believe) about 1/4th the power at about 15wpc, but SE output.
I'm not too familiar with the x-amps or the AlephX, but they will be more efficient. I did see on the Pass Lab site that the 150X has 32VDC rails. The AlephX is probably what you want. Check out this thread. It'll take a lot of reading, but I think you'll find what your looking for.
http://www.diyaudio.com/forums/showthread.php?s=&threadid=3748
Get out the bi-focals,
Rodd Yamashita
nania,
You can get any transformer secondary configuration from "Victoria Magnetics". And usually in less than a week if you pay by paypal or whichever way is the fastest way of payment.
You can get any transformer secondary configuration from "Victoria Magnetics". And usually in less than a week if you pay by paypal or whichever way is the fastest way of payment.
Does your transformer have a dual voltage primary [110 or 220]
if so just apply 110v to the 220v input.
Good luck, bob12345678
if so just apply 110v to the 220v input.
Good luck, bob12345678
mrfeedback said:
Mr. Feedback, you are very sharp man. I don't know if it's because of Groman, but everybodys sense of humour increased recently. I guess it's a good thing.😉
Coulomb said:
You might be surprised with what I measure on my Aleph5. With 300 VA Plitron toroid rated 25-0-25 V the rails are at at 32V. The AC voltage from the wall is 120V. I guess you still love this Forum.😉
Unfortunately peter the plitron transformers are only wired for 115 VAC input. This means you have made a basic assumption error. Transformers do exactly that, they transform whatever you feed them. At 120 VAC input you supplied a increase of Potential energy almost 5% x the division factor of the primary to secondary coil relationship of 2.2 that is a PD of 12.5%.
50 VAC x 12.5% = 58 Volts or so. there are some cooperative factors at hand so for the sake of argument call it 30 VAC per coil. The transfomer is sold as having and 4% regulation error so add that on top of the 30 VAC and you lose this argument. 🙂 🙂
Now if you get your self an AC Rheostat and set tthe input to 115 VAC and still come up with the same results, I will buy you lunch. 🙂
I thought the argument was about multiplier. You sggested 1.414, I did 1.25. With my Plitron transformer according to you I should be getting 35.35V DC, with my it should be 31.25. I measured 32 V DC on rails in my circuit. I guess it was closer to my calculations. 4% error on mains voltage works against you, because if I use variac I'll measure only 31 VDC on my rails and not 35 as you suggested with your multiplier. Where' the lunch?😉
Re Plitron 300VA
As a follow up Peter I just checked the Plitron site and the 300 VA has a 6% regulation error not 4% so it could be out by even more.
Anthony
As a follow up Peter I just checked the Plitron site and the 300 VA has a 6% regulation error not 4% so it could be out by even more.
Anthony
Well this is a fine pickle. 🙂
Your DC rails should be 35 DC, 50 VACx .7 or divided by 1.414. You recorded 32 VDC at 120 VAC input which indeed is unusual as you should have got 38 VDC, there is a 6 % regulation error but it would not account the difference you are getting. I can only assume the errors get more noticeable in the lower value transformers. I have always tested my transformers and had tem within a few volts ot the theoretical value, But I always use twice the required value for reserve power and hence almost always use 750VA and up.
I wouls still be happy to buy you and Mr. Pass lunch. 🙂
And gosh do I love this forum.
Anthony
😀
Your DC rails should be 35 DC, 50 VACx .7 or divided by 1.414. You recorded 32 VDC at 120 VAC input which indeed is unusual as you should have got 38 VDC, there is a 6 % regulation error but it would not account the difference you are getting. I can only assume the errors get more noticeable in the lower value transformers. I have always tested my transformers and had tem within a few volts ot the theoretical value, But I always use twice the required value for reserve power and hence almost always use 750VA and up.
I wouls still be happy to buy you and Mr. Pass lunch. 🙂
And gosh do I love this forum.
Anthony
😀
You missed my previous post. I noticed that Plitron transformers usually output more than specified. But as I said previously error works to your disadvantage because you should have even more DC But I wasn't. I believe that 1.25 multiplier, though quite conservative is right on point with class A bias.
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