Aleph 5

[BillyD]

Hi i started out building soz ,but i changed to aleph 5 i have a transformer 1005 va 50x4 sec will it work for aleph5?

[jonk]

If they have a 240 primary, hook up your 120V to them and you'll end up with 4 x 25, which should be fine for an A5. You could use a choke input and use it for A2.

[BillyD]

Thank you Jonk, for your help. I would like more of your advice. I have dual 120vac primarys and 4x50vac secondarys. How can I make this work?

[Tieftoener]

To better explain what jonk was saying...

you can hook up 120 to the two primaries in series (instead of parallel)... this would get you 4x25 on the secondaries, which would work well with the Aleph 5.

Normally, you'd hook up 240 in series on the primaries and 120 in parallel on the primaries. So if you put half the voltage in series on the primary windings, then your output would be halved. Make sense?

Hope this helps -

[BrianGT]

Originally posted by Tieftoener
To better explain what jonk was saying...

you can hook up 120 to the two primaries in series (instead of parallel)... this would get you 4x25 on the secondaries, which would work well with the Aleph 5.

This is correct. My question is, wouldn't this cut the power rating of the transformer in half, due to the different wiring of the primaries? 500VA is still enough for a Aleph 5, but I am curious if it would reduce that power handling.

--
Brian

[kilowattski]

Brian you may be correct. Suppose a transformer was rated at 360 VA. For arguments sake lets assume it is a perfect transformer and it is loaded to the maximum 360 VA. The max primary current @ 120 volts with the primaries in parallel is 3 amps with each primary handling 1.5 amps. When putting them in series at 120 volts we are allowing 3 Amps to flow through each secondary. The question is, can the toroid's individual primaries handle the extra 1.5 amps. The same type of situation could be true with the secondary. If we have a full 360 VA draw on the seconday with a lower output voltage you will be drawing more current. The real question is if the windings on the primary and secondary can handle the extra current? If you know what guage wire the transformer was wound with you can easily guess but if not a call to the manufacturer will need to be made for the answer.

[Tieftoener]

Good point on the wire gauges...

However, I think that the primary rating of a transformer has to do with the level of power that causes the core to reach saturation. In Avel Lindberg Y23 Series transformer specs, ALL the power class ratings (VA ratings) have the same core, regardless of the voltage. They weigh the same, the physical dimensions are the same, the termperature rise rating is the same, etc... With each different secondary output voltage in a power series (say, 625VA) the secondary current rating just lowers with respect to the secondary voltage going up. This translates to me as not changing the core, but only where the taps are made on the secondary. Below is a list of their specs:

625VA --> 25V+25V -- 12.5A --> (25*2*12.5=625)
625VA --> 30V+30V -- 10.42A --> (30*2*10.42=625.2)
.
.
.
625VA --> 60V+60V -- 5.21A --> (60*2*5.21=625.2)
625VA --> 115V+115V -- 2.72A --> (115*2*2.72=625.6)

So, all that said, I think that the current rating on BillyD's xformer will be double the original spec due to half the voltage output. Not sure if I'm 100% right - just speculating...

[kilowattski]

Tieftoener,

I think you are absolutely correct. I sell electronic test equipment for a living. I work for a large test and measurement company that begins with "T" and ends with an "X". As a matter of coinkydink I will be demonstrating an oscilloscope (second hint)for a power supply company tommorrow and will ask some questions so we can get the straight poop on the toroid question. Until tommorrow.....