Keen Ocean toroidal question

damiangt3

Member
2014-02-14 12:07 pm
I have a Keen Ocean TTO-13891 toroidal with the following secondary windings:

0-12v (0.25A) RED-RED
0-12V (6.25A) YELLOW-YELLOW

Before I make a silly mistake with the grounding can someone confirm that if I tap a wire off each of the yellows (or reds), join them together I have suitable ground? Or would I be better (read safer) attaching in a couple of diodes in series to create that ground?

Many thanks.
 
I don't understand your question. A transformer does not have a ground, but the circuit it feeds may need a ground. A ground is either the point from which you choose to measure voltages (signal ground), or a means of avoiding touching high voltages (safety ground).

There is lots on the internet, and this forum, about audio grounding.
 

damiangt3

Member
2014-02-14 12:07 pm
I don't understand your question. A transformer does not have a ground, but the circuit it feeds may need a ground. A ground is either the point from which you choose to measure voltages (signal ground), or a means of avoiding touching high voltages (safety ground).

There is lots on the internet, and this forum, about audio grounding.

Sorry, I shouldn't have written 'grounding' but 'creating a ground' for the power supply circuit (a +/- 10v LM317) which needs AC and a 0v.
 

rayma

Member
2011-04-29 8:37 pm

rayma

Member
2011-04-29 8:37 pm
damiangt3 said:
Sorry, I shouldn't have written 'grounding' but 'creating a ground' for the power supply circuit (a +/- 10v LM317) which needs AC and a 0v.
The transformer cannot provide "0v". You need to show us the PSU circuit you would like to use. It is the circuit which may provide a ground for the transformer, not the other way round.

Is it possible that what you mean by 'ground' is actually a transformer secondary centre-tap? If so, you need to connect one red wire to the correct yellow wire; the joint then acts as a CT. You can then use the transformer as 12V-0-12V at 0.25A.
 

damiangt3

Member
2014-02-14 12:07 pm
If you use just AC1 and 0 you will get half-wave rectification, so double the ripple voltage going into the regulator.

I better look at getting a transformer with equal dual secondaries :(

My long term goal is to have a play with my old Marantz CD5000 and feed each power consumer separately, I need +/- 10v & a 5v. I was hoping to use this transformer to supply the +/- 10v and using the +10v to provide the feed for a 5v superreg needed for the digital part of the circuit.
 
it doesnt work that way man , at all !!! ;-)

you'll need an other trafo for that job , 3 secondaries , 2 for your symmetric psu and one for your digital psu , best will be 2 trafo , digital and analog stuff "normaly" run with their own power supply , those stuff doesnt realy like to share ground or anything else .

in audio , power supply is a great part of the deal , the better you take care of them the better the result will be :)


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damiangt3

Member
2014-02-14 12:07 pm
it doesnt work that way man , at all !!! ;-)

you'll need an other trafo for that job , 3 secondaries , 2 for your symmetric psu and one for your digital psu , best will be 2 trafo , digital and analog stuff "normaly" run with their own power supply , those stuff doesnt realy like to share ground or anything else .

in audio , power supply is a great part of the deal , the better you take care of them the better the result will be :)


.

I know, I know I need to separate the digital and analogue but I want to start small. The CD5000 has one regulator (5v) which I've replaced with a superreg so replacing the crap that supplies it was my first thought.
 
Buy a 230:0-12, 0-12Vac dual secondary transformer.

It will need to be 10VA for each 130mAdc of output required.
eg. your +-10Vdc needs continuous 50mA and your 5Vdc needs 180mAdc then you total DC continuous current is 230mA. A 20VA would meet this demand.

Add a pair of lm317 regulators to regulate down to +-10Vdc,
Add a third regulator to create your +5Vdc supply.
 

damiangt3

Member
2014-02-14 12:07 pm
Buy a 230:0-12, 0-12Vac dual secondary transformer.

It will need to be 10VA for each 130mAdc of output required.
eg. your +-10Vdc needs continuous 50mA and your 5Vdc needs 180mAdc then you total DC continuous current is 230mA. A 20VA would meet this demand.

Add a pair of lm317 regulators to regulate down to +-10Vdc,
Add a third regulator to create your +5Vdc supply.

Thank you Andrew. The audiowind regulator I've purchased covers the +/-10v, I've got a Dexa Technologies NewClassD Regulator to provide the 5v.

I did struggle with calculating the transformer sizes so thanks for those details.