Very Simple Transformer amplifier.That's it.
Quality is bad on low volumes.This amp isn't designed for home use.It's for high power using.On high power distortion is very low.He have sound like of tube amps (because of transformer).There's only few parts,must try it.I'll post pics later to see what I talking about.Transformer is step-up one,and can have other ratio.If transformer ratio is high,you can put small voltage on input,but a higher current.I used small one from old TV.This transformer is used for output amp. and speaker.He is cca. 1cm high and 1cm wide. Wires from speaker now is my primary.Secondary goes to transistors (current amp.)There's two versions,one with bias pot. (max bias 25mA with +/-35V) and another without bias set,trimmed to ~8mA.Don't use higher voltage than +/-35V or bias will increased.You can put Vbe multiplier instead of pot.But ofset is best: 0mV at all.For high power is OK,I was put one module on my tractor,with simple SMPS 😀
Speaker can be 4ohm or higher.
This is all for now,I'll post pic's later 😉
Quality is bad on low volumes.This amp isn't designed for home use.It's for high power using.On high power distortion is very low.He have sound like of tube amps (because of transformer).There's only few parts,must try it.I'll post pics later to see what I talking about.Transformer is step-up one,and can have other ratio.If transformer ratio is high,you can put small voltage on input,but a higher current.I used small one from old TV.This transformer is used for output amp. and speaker.He is cca. 1cm high and 1cm wide. Wires from speaker now is my primary.Secondary goes to transistors (current amp.)There's two versions,one with bias pot. (max bias 25mA with +/-35V) and another without bias set,trimmed to ~8mA.Don't use higher voltage than +/-35V or bias will increased.You can put Vbe multiplier instead of pot.But ofset is best: 0mV at all.For high power is OK,I was put one module on my tractor,with simple SMPS 😀
Speaker can be 4ohm or higher.
This is all for now,I'll post pic's later 😉
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I guess it will depend on whether you are looking for quality sound or something cheap and dirty will do for a bit of fun.
I'd go for the fun side of this design. 😉
I'd go for the fun side of this design. 😉
If transformer is from the old TV it is probably for use with TDA1015. My old Toshiba TV used TDA1015 IC transformer coupled with loudspeaker. I do not know why transformer is used when TDA1015 can drive loudspeaker directly.
Im guessing, but as I recall, Japanese design colour televisions were once mainly live chassis, so speakers and aerial connections had to be very safely isolated. Many sets also had extension speaker/headphone connections and this meant isolation transformers rather than just caps to isolate the external connections. That's how an old Sanyo set of mine was described, at least.
Ian,
You are 100% right! I found service manual for my old TV and everything is just as you described including extension headphone connections.
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