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sigma25 questions

post #1 of 13
12/30/09 at 11:03am
Thread Starter 
I have a few questions about the sigma25:
-I want to use the sigma24 as transformator but the sigma25 page says something about the input voltage and the output voltage which doesn't agree with the sigma24. Can I still use the sigma 24 for 5V output?
-I want to use the sigma25 as powersupply for the gamma1/2 and as a mini3 charger. Is this possible?

Thanks in advance,

nemmo
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post #2 of 13
12/30/09 at 11:39am
Quote:
Originally Posted by amb View Post
Just FYI, if you're planning to build a σ25 PSU with a σ24 transformer mounting board for use with a γ1+γ2, a 2.8VA 9V EI-30 transformer should work well. The σ25 should be configured to output 5V DC.

Part numbers:

Digi-Key: 567-1040-5-ND (115V primary) or 567-1042-5-ND (230V primary)
Farnell: 1689068 (230V primary)
RS components: 347-3524 (230V primary, 3.2VA)

Mouser does not stock any EI-30 transformers with the needed specs . However, if you're going to be powering a γ1 only (no γ2), you can use Mouser 673-030-7151-0

Alternatively, you can use an Amveco TE62011 (Digi-Key TE62011-ND) or TE62021 (TE62021-ND) toroidal transformer, and skip the σ24 PCB. These transformers have two 9V secondary windings which should be wired in parallel. They also have two primary windings which should be wired in parallel for 115V AC mains, or in series for 230V.

You could also use an AC or DC wallwart (unregulated) rated at 9V 300mA or above instead of a transformer.
Running a Mini3 will be a problem though, as it would need an output of 12VDC.
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post #3 of 13
12/30/09 at 11:39am
Quote:
Originally Posted by nemmo View Post
I have a few questions about the sigma25:
-I want to use the sigma24 as transformator but the sigma25 page says something about the input voltage and the output voltage which doesn't agree with the sigma24. Can I still use the sigma 24 for 5V output?
-I want to use the sigma25 as powersupply for the gamma1/2 and as a mini3 charger. Is this possible?

Thanks in advance,

nemmo
Note sure what your question is? The sigma24 is just a nice way to mount El-30 transformers and pairs up nicely with the sigma 25. You need to make sure the transformer you get has the proper voltage and power capability for your project. FYI - you will not be able to get one power supply to provide power for BOTH the gamma1 and the mini3.
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post #4 of 13
12/30/09 at 11:51am
What part of sigma24 says that it can't be used with the sigma25?

As for using the sigma25 to power both the gamma1/2 and Mini3, the Mini3 needs 15-24V input and the gamma1/2 by default needs 5V. If you use the LP2985 regs as an option, they can tolerate 16V inputs, so it is possible.
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post #5 of 13
12/30/09 at 12:09pm
Thread Starter 
Desired output voltageTransformer secondary voltage
5VDC9VAC
6VDC9VAC
8VDC9VAC
9VDC12VAC
10VDC12VAC
12VDC12VAC
15VDC15VAC
18VDC18VAC
24VDC24VAC

The sigma24 transformator says 12VAC and I wanted 5VDC. I asked it just to be sure.

And do I have to leave the C4 of the sigma25 open? Because I don't want 24V output.
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post #6 of 13
12/30/09 at 12:19pm
Quote:
Originally Posted by nemmo View Post

The sigma24 transformator says 12VAC and I wanted 5VDC. I asked it just to be sure.
Quote:
The listed power transformer is appropriate for an ε24 circuit. For the σ25 you should read the "Transformer selection" section at the σ25 website to determine the correct transformer for your application.
That is the part of AMB instructions that is important
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post #7 of 13
7/17/10 at 12:23pm
Quote:
Originally Posted by m1abrams View Post

Quote:
Originally Posted by nemmo View Post

The sigma24 transformator says 12VAC and I wanted 5VDC. I asked it just to be sure.
Quote:
The listed power transformer is appropriate for an ε24 circuit. For the σ25 you should read the "Transformer selection" section at the σ25 website to determine the correct transformer for your application.
That is the part of AMB instructions that is important

 

what would happen if you got a transformer too big for the application? would it be overkill or would it cause damage to the circutry?
 

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post #8 of 13
7/17/10 at 3:29pm

The σ25 will just get hotter due to the extra voltage it has to drop.

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post #9 of 13
7/17/10 at 4:15pm

I'd use 9VAC maybe even 6VAC for 5VDC as 12VAC will have the regulator dropping about 10V, a little higher than what I would recommend, regulator will get pretty hot driving that Gamma1/2 

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post #10 of 13
7/17/10 at 4:54pm

With the 311mA 9VAC transformer for the σ24/σ25, paired with a y1+y2, the combo will get hot. In an unventilated ABS case, using my multimeter's temperature probe, the transformer measured 50C.

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post #11 of 13
7/17/10 at 5:12pm

 

Quote:
Originally Posted by FallenAngel View Post

I'd use 9VAC maybe even 6VAC for 5VDC as 12VAC will have the regulator dropping about 10V, a little higher than what I would recommend, regulator will get pretty hot driving that Gamma1/2 

 

 

dang cause i got the 12VAC transformer by accident for the Gamma 1/2, do you think that is okay or should i get a smaller one?  though i was planning on making my own case, so maybe i could add some fans for ventilation

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post #12 of 13
7/18/10 at 2:33pm

I wouldn't install a fan, what about dropping the voltage a bit first, like a few extra 1N400x diodes after the bridge, probably would need to air-wire it.  Maybe even wire a couple of diodes/bridges at the AC input to drop a few volts.  2 extra bridges should get you to a good value. 

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post #13 of 13
7/18/10 at 2:52pm

what i did was found a old 6VAC wall wart sitting around, cut off the plug, wired it into the AC in on the sigma 25 board, wired up the plug, gets me the value i need too. now i need to figure out whats wrong with my gamma 1

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