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Transformer and Enclosure parts for powering a γ1/γ2

sigma25, sigma26, sigma24

Transformer and Enclosure parts for powering a γ1/γ2

Postby Gh0st » December 15th, 2013, 2:03 pm

Hello all,
I'm going to be building a Gamma1 DAC in the near future (Which I will eventually upgrade to a Gamma2), and I have a few questions about how to best build a Sigma25 to fit my needs.
Now, I've built DIY Audio components, but I have almost no experience regarding power supplies (I usually build portable things).
Going off of the Gamma1 site, I need one of the following transformers:
Pulse BV030-7597.0 2.8VA EI-30 (With Sigma24)
Amveco TE62011 3.2VA toroidal
Amveco TE62021 5VA toroidal
Which leads me to my first question: What are the advantages/disadvantages of a toroidal transformer over an EI-30 transformer?
Also, if a Toroidal transformer is better, which of the two Amveco transformers would be better for this purpose?
What type of enclosure would be best for the project? It doesn't need to be a low profile enclosure or anything like that, although it would be nice if it didn't take up much desk space.
Finally, what resource could I use to learn how to hook up the transformer to the Power Supply and how to hook up the AC power to the transformer?
Thanks for all of your help!
EDIT: One last question: I found the Epsilon24 on the AMB site, and the concept of the momentary switch appeals to me. However, I'm getting a bit confused on one thing: Is the Epsilon24 a regulating power supply in itself (Eliminating the need for a Sigma25), or does it still require a Sigma25? Also, if it is intended as a standalone supply, is there a way to install a momentary switch on a Sigma25, or will the Epsilon24 provide the same performance as a Sigma25?
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Re: Transformer and Enclosure parts for powering a γ1/γ2

Postby amb » December 16th, 2013, 2:32 am

Gh0st wrote:What are the advantages/disadvantages of a toroidal transformer over an EI-30 transformer?

How about this: Wikipedia: Transformer types
The differences tend to be of minimal importance in a small, outboard, regulated power supply. Just use one that fits with your physical requirements.

Which of the two Amveco transformers would be better for this purpose?

The only difference is the VA rating and physical size. If you ever plan to power something else that may require more output current then use the higher-rated one. The drawback is the larger the transformer, the stronger the magnetic field, so if you put it close to analog audio circuitry it may induce hum. The size difference would directly influence which enclosure you may use.

What type of enclosure would be best for the project? It doesn't need to be a low profile enclosure or anything like that, although it would be nice if it didn't take up much desk space.

Some people who built γ2s also used a taller version of the same casing (Box Enclosures B3-080). You can find some photos in this forum. But that's just an example of infinite possibilities.

Finally, what resource could I use to learn how to hook up the transformer to the Power Supply and how to hook up the AC power to the transformer?

The fact that you have to ask this question means that you should seek someone more experienced to help you (hands on) with the first built that involves AC line voltage. But this is the basic idea:

Image

Depending on the IEC module you choose, it may have the fuse, switch, and possibly an AC line filter built-in.

Note that the transformer shown above is a single-primary, single-secondary unit, for simplicity's sake. The Amveco toroids have two primaries and two secondaries. You would need to wire them like this:

Image

In both cases the secondaries are in parallel because we have two 9V secondaries and we want 9V, and paralleling them gives you the full VA rating of the transformer. The phase of the windings and how you wire them is important, denoted by the little round dots in the diagram.

What's not shown is that all wiring should be mechanically secure, and no line voltage should be exposed (so that it might come in contact with a finger or any other object). Use shrouded FastOn connectors on the IEC module and heat-shrink tubing anywhere you have to splice wires together.

One last question: I found the Epsilon24 on the AMB site, and the concept of the momentary switch appeals to me. However, I'm getting a bit confused on one thing: Is the Epsilon24 a regulating power supply in itself (Eliminating the need for a Sigma25), or does it still require a Sigma25? Also, if it is intended as a standalone supply, is there a way to install a momentary switch on a Sigma25, or will the Epsilon24 provide the same performance as a Sigma25?

ε24 is not a "power supply", it's just a power switch management circuit that allows you to use a momentary pushbutton to trigger a relay which would then act as the actual power switch. It has its own onboard 12V DC power supply (and it needs its own power transformer that's wired to be "always on"), but it is not intended to be used to power anything else. Essentially, think of the ε24 (plus its transformer and relay) as a "replacement" of "SW" in the first diagram above.
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Re: Transformer and Enclosure parts for powering a γ1/γ2

Postby Gh0st » December 16th, 2013, 5:09 am

Thanks for all your advice, amb!
I guess with the E24, I was getting confused on the fact that the E24 shares hardware with the Sigma25. Now I see that the power segment is specifically for the E24.
What I'm seeing regarding Transformers is that a toroidal will reduce EMI, which will be good since I'm just stacking the y2 on top of the Sigma25.
I'll also look around and see if I can find someone to assist with the Sigma25 build, per your suggestion.
One final question, though: If I were to use the e24 in this build. how would I wire that and the Sigma25 into the IEC?
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Re: Transformer and Enclosure parts for powering a γ1/γ2

Postby amb » December 16th, 2013, 12:01 pm

Gh0st wrote:One final question, though: If I were to use the e24 in this build. how would I wire that and the Sigma25 into the IEC?

The ε24's power transformer needs to be "always on", so its primary should be wired similarly to the diagram above except it's before the switch. The secondary side is the same as above, but it goes to the ε24.

If this description is not clear, then let me know and I'll draw another diagram.
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Re: Transformer and Enclosure parts for powering a γ1/γ2

Postby Gh0st » December 16th, 2013, 12:52 pm

Alright, I think I understand it now.
From what I'm hearing, I'll have the E24's primary leads wired to the IEC, and the secondaries to the E24.
Then, I'll have leads running from the left side of the IEC (side with the fuse) to the E24's relay, then have 2 of the primaries for the Sigma25's transformer hooked to the 'on' side of the relay, with the other two hooked to the other side of the IEC normally.
This is what you're suggesting, right?
EDIT: I just presented the schematic of my suggestion to someone with experience regarding AC line voltage and electrical circuits, and they claimed that it would work.
Thanks for all of your help! I'll be sure to post pictures of the Sigma25/E24 when I'm done.
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Re: Transformer and Enclosure parts for powering a γ1/γ2

Postby amb » December 16th, 2013, 1:19 pm

Here is a diagram incorporating the ε24:

Image

Not shown in this diagram is the wiring from the ε24 to the momentary switch, the illumination LEDs, and the thermal-breaker loop (which you will not use and will simply jumper across the onboard connector).
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Re: Transformer and Enclosure parts for powering a γ1/γ2

Postby Gh0st » December 16th, 2013, 7:16 pm

Ah, thanks for the additional clarification.
That diagram matches the one I showed to the person who will be assisting me with the build (Engineering teacher).
Thanks for all your help! If I have any more questions, I'll be absolutely certain to contact you!
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