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Old 9th January 2013, 09:42 PM   #21
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Default tkx

tkx for all your help
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Old 13th January 2013, 08:40 AM   #22
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Default power supply?

any suggestions o the power supply ... should i build a small smps?
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Old 13th January 2013, 09:36 AM   #23
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which one is better?

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or

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... tkx
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Old 13th January 2013, 01:37 PM   #24
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Both of them will not work. There are 2-5 volts ripples of charging current present in car power. Relatively to the source ground this virtual ground will consist half of potential of those ripples. Shortly, it will be equal to applying 1-2 volt noise to the input of your crossover.
To avoid power supply noise the only option is the switching supply with both voltages taken from same transformer and ground galvanically isolated from car power.
If you don’t mind to tweak with it, you can build your own PS. There is pretty much of controllers to do it. Someone already did similar work.
http://powersupply88.com/bipolar-15-v-and-5v-from-car-battery-supply.html
Or you can use manufactured DC/DC converter with bipolar output voltage.
3-5 watt will be sufficient. On cars with old and sulfated battery, the charging voltage can achieve 20-25 volts and you need in converter with max input voltage rated higher those numbers.
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Old 13th January 2013, 02:12 PM   #25
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what about sg3525 in a push-pull config?
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Old 13th January 2013, 02:27 PM   #26
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Old 13th January 2013, 02:36 PM   #27
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whit LM7812 and LM7912 on the output of the bridge rectifier
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Old 13th January 2013, 03:00 PM   #28
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I think I'm going to use an E tipe core from a ATX power supply a little bit smaller then an ETD19

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Last edited by adytzu22; 13th January 2013 at 03:15 PM.
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Old 13th January 2013, 04:20 PM   #29
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Default transformer

primary:
6 turns CT 6 turns

secondary:
11 turns CT 11 turns

using 0.8 mm wire

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Last edited by adytzu22; 13th January 2013 at 04:31 PM.
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Old 13th January 2013, 06:46 PM   #30
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You are moving in right direction. Look in simulator how much of current consumes your circuit with applied 50 and 1000 Hz signal of maximal amplitude. I think it should be no more than 50mA. Of course you donít need in such powerful switches and thick wire. The 0.8mm wire is overkill.
One more project http://sound.westhost.com/project69.htm
Number of turns for primary winding depends on frequency, voltage, core cross-section area and ferrite permeability.
Taking into account that there can be more than 12 volts, for this core and 30kHz frecuency , Iíd put 50-80 (the more the better) turns of primary winding
Minimal wire diameter 0.3-0.4 mm for primary winding, and 0.25mm for secondaries
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