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Projects Q/A / Win a Free SIGLENT Oscilloscope or Generator!
« Last post by micemic on July 28, 2014, 09:56:36 PM »
Has anyone ever bought a SIGLENT product?  ;D    I have seen an activity on a website.  ---SIGLENT Technologies is awarding free oscilloscopes or generators to many of our valued customers as a sign of our appreciation for your support and trust in SIGLENT. The way to enter is easy and will help us with your feedback and suggestions on better products and support.
http://www.siglent.com/newsletter/2014-7-22-en/2014-8-1.html   


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Projects Q/A / Re: 0-30V Stabilized Power Supply
« Last post by Hero999 on July 27, 2014, 03:46:08 AM »
A transformer with a dual 28V secondary winding will do.

D11 will protect the output in case of reverse polarity.

Another diode can be placed with the anode on +Vout and the cathode to the positive of the bridge rectifier to protect against brief positive high voltage spikes entering +V. You could also consider a transorb across the bridge rectifier to protect against transients.
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Projects Q/A / Re: 0-30V Stabilized Power Supply
« Last post by rvendrame on July 26, 2014, 07:52:17 PM »
I have never seen a power audio amplifier that needs a regulated dual-polarity supply. They use a center-tapped transformer, bridge rectifier and two big filter capacitors.

If you build two of this project and power them from a center-tapped transformer, joining the projects at the tap then I think the negative supply in each project will not work properly.

Sorry, I want a dual PS to use in the bench.  I've build some power amplifiers and might use the PS just for testing them during repair.  I'm just trying to find one more 'fail proof' to short circuits, nothing else.

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Projects Q/A / Re: 0-30V Stabilized Power Supply
« Last post by audioguru on July 26, 2014, 06:58:17 PM »
I have never seen a power audio amplifier that needs a regulated dual-polarity supply. They use a center-tapped transformer, bridge rectifier and two big filter capacitors.

If you build two of this project and power them from a center-tapped transformer, joining the projects at the tap then I think the negative supply in each project will not work properly.
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Projects Q/A / Re: 0-30V Stabilized Power Supply
« Last post by rvendrame on July 26, 2014, 06:38:33 PM »
When you make two completely separate supplies, one can be 0V to +30V and the other can be 0V to -30V. If one or both outputs are shorted to 0v then that supply will safely regulate its output current to the amount of current that is set at.
The supplies have no protection from an output voltage or current of the wrong polarity so if +30V is shorted to -30V then one or both supplies might blow up.

Thanks.  In that regard,  a dual supply with a central-tap transformer (like this one http://www.electronics-lab.com/projects/power/030/index.html) would be more 'fail proof'?  Or will blowup / smoke exactly like?  My goal is to work with audio in hobby projects (preamps, amplifiers etc)


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Projects Q/A / Re: 0-30V Stabilized Power Supply
« Last post by audioguru on July 26, 2014, 11:01:59 AM »
When you make two completely separate supplies, one can be 0V to +30V and the other can be 0V to -30V. If one or both outputs are shorted to 0v then that supply will safely regulate its output current to the amount of current that is set at.
The supplies have no protection from an output voltage or current of the wrong polarity so if +30V is shorted to -30V then one or both supplies might blow up.
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Projects Q/A / Re: 0-30V Stabilized Power Supply
« Last post by rvendrame on July 26, 2014, 09:15:58 AM »
Hello all,

That's a very nice initiative + community + development here in this post.  Congratulations to all of you!!!

I will start to build my PS soon, and I have a quick question.  In case I make two of them, as liquibyte did  ---  Does the short-circuit protection will still working across the + 0 - outputs?  Or will it blow up in case of short-circuit between the + and - output, or even between the +/- and the zero?

Thanks
Ricardo
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Projects Q/A / Re: 0-30V Stabilized Power Supply
« Last post by redwire on July 25, 2014, 11:26:40 AM »
Ops, sorry, I was thinking in another piece at the time.  :P

Not even farnell have this one in DIP socket here.

I will have to find something similar to this.



Then build it with the SOIC 8 package.   You will have a choice between  the TLE2141 or the MC34071.
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Projects Q/A / Re: 0-30V Stabilized Power Supply
« Last post by thiagoas on July 24, 2014, 10:46:02 PM »
Ops, sorry, I was thinking in another piece at the time.  :P

Not even farnell have this one in DIP socket here.

I will have to find something similar to this.


Edit.
I requested samples from TI, let's see what I get. :D
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Projects Q/A / Re: 0-30V Stabilized Power Supply
« Last post by audioguru on July 24, 2014, 08:16:43 PM »
Would NE5532 work in this circuit? I have no LME2141 in my country.
The LME2141 is not available anywhere because nobody makes it. You have the wrong letters.

The TLE2141 is made by the world's largest semiconductor manufacturer, Texas Instruments, and should be available everywhere.
It was selected because its maximum supply is 44V, its inputs work at 0V without a negative supply and its output goes down to almost 0V.

The NE5532 also has a maximum 44V supply but its inputs do not work below 3V and its output does not go below 2V so the circuit and spec's for the project must be changed for it to be used. 
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