Power Supply Question

[odyseus]

Hi All,
I'm trying to come up with an alternative to powering Daniels rectifier circuit (Diode bridge rectifier+Filters) without having to use a 0-12V,0-12V mains transformer. The health and safety rules in the UK are very hard, so I don't want to be sued if someone connects the rectifier circuit incorrectly and they get an electric shock.

I have tried connecting a 24V AC-AC power supply to the rectifier circuit but I don't get equal supply voltages ie +25V and -10V?? I also tried using Marco's single rectifier ie two diodes and two electrolytic capacitors but again I got incorrect voltages. The PSU I have does have an earth pin. but I don't know why this should be an issue.

Could someone share an alternative power arrangement involving using the 24V AC-AC transformer but still using Daniels PSU board??

Cheers

John

[odyseus]

Replying to myself.

The bridge rectifier will only work with a centre-tapped transformer, so that 0V can be set...

For the two diode rectifier - this is in fact a voltage doupler rectifier circuit, so my 24V AC-AC transformer was supplying a large +/- 38V!!!

I have now ordered a 15v AC-AC transformer, which should give me @ +/- 22V...

[weather1967]

Hello Odyseus
I use tranformer 1x12 VAC to output and i have the Danniel design with 2 diodes 1N 4007 and 2 hulectrolitik capacitors 100μF for to have DC voltage 19 V.

http://i42.servimg.com/u/f42/11/22/64/62/power516.jpg

And all the equipment is here :
http://www.geocities.com/peristerimeteo/lightingradar

[41south]

I have a couple of PC (ATX type) power supplies laying about at home from old computers. They typically have +12VDC and -12VDC outputs available and are easily modified. Would one be suitable for this project or do I need to look for something with a higher voltage output?

Thanks
Colin.

[weather1967]

Hello Colin
You are little down from the limit 13,8 VDC from electronic circuit with 2 transformers

http://users.edpnet.be/Danielv37/Detect ... Rev_21.pdf

You can do a test and to see if it work with 12 VDC .
Personal opinion but i am not 100% sure i thing it will work ,but wait and from others members where they have more experience answer to you about it.

[41south]

In looking further I think I will use this kit from Jaycar electronics here in NZ with a 1 amp AC plug pack

http://jaycar.co.nz/productView.asp?ID=KC5038

Thanks
Colin.

[ZaventemLR]

Hello Collin,

I tested the minimum voltage to be applied on the kit to get a good regulation from the LM317 and LM337.

The regulators give an output voltage between +/-11.4V too +/-11.6V following tolerance of the resistors.

To obtain a good regulation and a minimum of noise, we must supply the kit with 2.5V higher than the output voltage.
Thus, the kit must be supply with (11.6V + 2.5V) 14.1V minimum.

It’s why I propose to use a minimum voltage of +/- 15V to supply the kit.
That will avoid some problems, like loss in the line, temperature problem, etc.

I do not think that the little "Universal +/-15V Power Supply" will help you.
There are already all components on the KIT.
You just need a transformer, 2 diodes and 2 capacitors of 1000uf/63V to build a symetrical power supply.
Like Dimitir say, on the PDF file I suggest some alternatives to build a fast, simple and not expensive power supply.

Best regards

Daniel

[weather1967]

Hello all.
I agree with Daniel and thanks for this useful test ,Colin it not neccesary to build Universal +/-15V Power Supply ,There are already all components on the KIT.
One correction Daniel ,in your electronic design the 2 hylectrolytik capacitors is 100 μF 35 volt

http://users.edpnet.be/Danielv37/Detect ... Rev_21.pdf

[ZaventemLR]

Yes Dimitri, on the PDF there are 100uF

I propose to use 1000uf that work better.
I tested during the start-up of the HQG antenna with 100uF and 1000uF last week-end.
I noticed a small improve with 1000uF.

Daniel

[weather1967]

Ok Daniel ,i suppose the more μF at hylectrolytik capacitors is better, it decrease the noise .