Finished Car Amplifier schematic + PCB based on Kenwood KAC-716

[Perry Babin]

JLH:
I don't think the W material is going to be suitable for a power transformer. The F and P materials are good choices (P is my choice when I build supplies). Contact the manufacturer or distributor if you decide to use the W material to see if they believe it's suitable for a power transformer.

[JLH]

The below quote is from Perry's web site. I've Googled around, but cannot find any references to the 20% winding factor for toroidal cores. What is the rationale for it? Is it a known good balance between copper losses and good magnetic coupling between primary and secondary? At face value it makes me think about the primary copper losses more than anything.

OK, now that you basically know how much copper you need (considering the duty cycle, maximum power and current draw), you have to have a core that can hold the primary and secondary windings. Many times, the primary and secondary will have approximately the same amount of copper on the primary as on the secondary. If you have a transformer with a 1:3 ratio, the length of wire for the secondary will be three times as long as the wire on the primary but the current passing through it will be 1/3 as much so the circular mils of the secondary will be 1/3 that of the primary. For this supply, the secondary uses a single 14g wire where the primary uses three parallel 14g conductors. What this means is that the core will have to hold approximately double the copper used for the primary alone. For toroidal cores, the 'winding factor' is generally 0.2 (20% of the window area filled with copper). It can be more or less but this is typically what's used in the various calculations.

[vasko]

Originally Posted by luka

if you really need feedback, it would be done pretty much the same as with SG
find one that has TL and has feedback... I think you will only need hand full of components more for that

TL494 has DTC pin 4, Feedback pin 3, 4 inverting/noninverting pins 1,2,15,16, I've attached image from datasheet.

I'm confused which all pins are for U an I control???

[Perry Babin]

The 0.2 winding factor is for the primary. It's not critical.

Page 4:
http://www.mag-inc.com.cn/file%20lib...wer_design.pdf

[JLH]

Originally Posted by Perry Babin

The 0.2 winding factor is for the primary. It's not critical.

Page 4:
http://www.mag-inc.com.cn/file%20lib...wer_design.pdf

That's a really nice tech paper. What I find most interesting is how little capacitance and inductance is required at these higher switch frequencies. In one of my SMPS examples I calculated 4.9uF and 1.4mH. Due to the waves being square instead of a sine wave, once rectified there's not much left to do because its basically DC at that point. We just need to clean up the ringing and noise. I also see why having a perfect 50% switching duty cycle for the MOSFETs is so critical. These SMPS are very interesting beasts.

[Luisile]

Hay Risto and what about making amp module baced on Kenwood Kac-719?
it have 2 pairs of output transistors. Sorry for my poor english.

[Luisile]

Hay Risto, and what about making a PCB for kenwood kac-719? it ha 2 pairs of output transistors. sorry for my poor english

[thushara]

HI.
got you'r nice amplifier with schematics, but it has no mention any where about smps transformer, if its home buil one, plz give the spec of that transformer,
thank you.