I'm not sure 'over built' would translate well, it is a complement. 
Your selection of parts for the power supply are quite good. You could probably go so far as to power additional boards like a subwoofer or center channel, biamp the tweeters. If this amp is meant to be used in anything smaller then an auditorium it has more then enough power to rattle the windows.
You are in a sweet spot for voltages: High enough for most power amp designs but still low enough for devices like 7805, 7912, ... regulators, they accept voltages up to 37V. If you ever want to add preamp, tuner, MP3 player, ??? you have the perfect set up.
Only thing that could sink you are safety measures to insure something outside of your control does not get you. Variations in line voltages, lightning strikes, transient spikes when powering up, knucklehead friend that turns the volume up to 11, that kind of thing.
I'm the worlds worst person at playing it safe. That being said, if you haven't already decided to do so, you may want to add fuses on the 120 VAC line, each of the 35 V rails, and the speakers.
Another safety addition would be Metal Oxide Varistor MOV
For operator safety and some level of protection you may want to add a bleed resistors to the power supply. Just a fairly low resistance power resistor across each of the rails to bleed the charge off the power supply capacitors. Something in the 2-3k Ohm range, 2-5 Watts sounds about right but I haven't calculated it out. The power amp does draw some idle current that would perform the same function but bleeder resistors are a nice fail safe especially if you solder them on the capacitor terminals.
Your selection of parts for the power supply are quite good. You could probably go so far as to power additional boards like a subwoofer or center channel, biamp the tweeters. If this amp is meant to be used in anything smaller then an auditorium it has more then enough power to rattle the windows.You are in a sweet spot for voltages: High enough for most power amp designs but still low enough for devices like 7805, 7912, ... regulators, they accept voltages up to 37V. If you ever want to add preamp, tuner, MP3 player, ??? you have the perfect set up.
Only thing that could sink you are safety measures to insure something outside of your control does not get you. Variations in line voltages, lightning strikes, transient spikes when powering up, knucklehead friend that turns the volume up to 11, that kind of thing.
I'm the worlds worst person at playing it safe. That being said, if you haven't already decided to do so, you may want to add fuses on the 120 VAC line, each of the 35 V rails, and the speakers.
Another safety addition would be Metal Oxide Varistor MOV
For operator safety and some level of protection you may want to add a bleed resistors to the power supply. Just a fairly low resistance power resistor across each of the rails to bleed the charge off the power supply capacitors. Something in the 2-3k Ohm range, 2-5 Watts sounds about right but I haven't calculated it out. The power amp does draw some idle current that would perform the same function but bleeder resistors are a nice fail safe especially if you solder them on the capacitor terminals.
i'm using heatsink and fan from old pc psu running at full speed,and also i gambled all my thought's and connected 4 ohms little speaker just in case so i turned on tda7293 amplifier and it worked, it didn't done anything stupid,i think everybody knows that feel then you do something and its works in successful way. I upload photo later with heatsink and then you say is it good or to small even with fan
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It's 230VAC in my country since i live in Europe,so what fuse i should use on mains? now i'm using 3A fuse on mains is it to big or to small?not using fuses on 35Vdc and i want to make safe the amps input rather than output because input is very very sensitive...i dont say that i shouldn't use fuse on output just say that need to make input safe first any ideas how to do that?i was thinking to use small fuse on inputs signal wire but it wont work because that way gnd is left unfusedI'm not sure 'over built' would translate well, it is a complement.
You are in a sweet spot for voltages: High enough for most power amp designs but still low enough for devices like 7805, 7912, ... regulators, they accept voltages up to 37V. If you ever want to add preamp, tuner, MP3 player, ??? you have the perfect set up.
Only thing that could sink you are safety measures to insure something outside of your control does not get you. Variations in line voltages, lightning strikes, transient spikes when powering up, knucklehead friend that turns the volume up to 11, that kind of thing.
I'm the worlds worst person at playing it safe. That being said, if you haven't already decided to do so, you may want to add fuses on the 120 VAC line, each of the 35 V rails, and the speakers.
Another safety addition would be Metal Oxide Varistor MOV
For operator safety and some level of protection you may want to add a bleed resistors to the power supply. Just a fairly low resistance power resistor across each of the rails to bleed the charge off the power supply capacitors. Something in the 2-3k Ohm range, 2-5 Watts sounds about right but I haven't calculated it out. The power amp does draw some idle current that would perform the same function but bleeder resistors are a nice fail safe especially if you solder them on the capacitor terminals.
Hi sonyzz!
Audio amplifier with IC-TDA7293 and with power supply 2x24Vac(+/-32Vdc)/150VA for mono, will work without a care in speakers with impedance of 4R!
Making it! makin it audio amplifier with tda7293 and enjoy in his sound!
Cheers!
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transformer is 200VAHi sonyzz!
Audio amplifier with IC-TDA7293 and with power supply 2x24Vac(+/-32Vdc)/150VA will work without a care in speakers with impedance of 4R!
Making it! makin it audio amplifier with tda7293 and enjoy in his sound!
Cheers!
Hi,
Po=(2xUcc)2/8R is RMS power for audio amplifier.
Po=(2x32)2/8x4=128W(rms)!
Ucc=+/-32Vdc
cheers!
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for mono 150VA and min P=250VA for stereo amplifier with tda7293 for spekers with 4R!transformer is 200VA
4x10000uF/50V electrolitics caps-for stereo!
Best regards!
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i use one tda7293 because i only have one Radiotehnika's S-90 speakerfor mono 150VA and min P=250VA for stereo amplifier with tda7293 for spekers with 4R!
4x10000uF/50V electrolitics caps-for stereo!
Best regards!
and i know theese little chips have power to shake windows 
Your supply is fine and probably so will your heat sink. Go ahead and test it out. Only make sure you have not made any mistakes with power supply polarity . Do not connect the speaker when powering up. Check the speaker output for dc. It should read close to zero. You can then connect the speaker and test your amp.
PCB for stereo amplifier with TDA7293
I agree!
This is how it looks for PCB stereo version wih the TDA7293.
Enjoy!
I agree!
This is how it looks for PCB stereo version wih the TDA7293.
Enjoy!
Attachments
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It's 230VAC in my country since i live in Europe,so what fuse i should use on mains? now i'm using 3A fuse on mains is it to big or to small?not using fuses on 35Vdc and i want to make safe the amps input rather than output because input is very very sensitive...i dont say that i shouldn't use fuse on output just say that need to make input safe first any ideas how to do that?i was thinking to use small fuse on inputs signal wire but it wont work because that way gnd is left unfused
I think 3A is a bit high but not anything to lose much sleep over. If you go with ~2A that would blow when your 220VA was asked to put out ~400VA. I think that would still be enough handle the surge when you first turn on the amp.
Why you should consider fuses on the rails. You have some nice capacitors on the supply rails. Obviously a good choice for filtering and reserve power for demanding music. *IF* for some reason the 7293 fails, it may act as a dead short to ground. If that happens, the capacitors will discharge through that dead short and the results can be exciting! But I don't even follow my own advice. I have two or three non fused, in the manner I am talking about, power supplies I use all the time.
I'm not sure about what you mean with input sensitivity/protection. If you mean full volume with the volume turned 1/2<?> then you can add a resistor on the line in. Hard to guess what you are currently using for a volume pot, audio taper, ... but something in the range of 1000-5000 Ohms would be a good starting range. That would reduce the voltage of the input and limit current, give fuller range to volume control. I really have problems with drunk friends seeing how loud my stereos will play. I haven't done it yet, but I will probably set the maximum volume on some of my amps that are about to make it out into the wild this way such that full volume on the knob will be ~90% of rated output.
about input protection - i'm saying that if tda7293 fails then voltage do not go through input to mp3 player or other music device because of the protection, but what protection to make - i'm still thinking
ah, also https://app.box.com/s/trlg3ffnys4ukv5gik8n have fuses on both main wireshttps://app.box.com/s/trlg3ffnys4ukv5gik8n
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and one more question is from what power cooling fan?install separate transformer as supply to fan or with resistor's and zener diodes drop voltage from 35v vs+/gnd to 12v and give to fan or use voltage regulator as lm317 (same method as dropping with resistor's and zener diodes) ? and is this dual fan configuration is good? cool air comes from fan 2,then comes through heatsink fins and hot air comes out from fan 1
heatsink is with fins:
heatsink is with fins:
No.
the fuse rating is the current that the fuse will pass forever.
Typical fuse will supply twice their rated current for a couple of minutes.
Twice the current rating for a 3A fuse is 6A.
6Arms into a 220Vac transformer is ~1.3kW for maybe a couple of minutes.
That fuse is far too BIG.
so 1A do the job and a little big because 1A x 230Vac = 230VA but transformer is 200VA so i think 1A will be good, also not 220Vac but 230Vac because from my wall socket i get 228-230Vac
transformer's photo http://www1.zippyshare.com/v/47503936/file.html
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I was thinking a fast acting vs. slow blow and ONLY in case of catastrophic failure. Something like a short in the primaries or the bridge rectifier dies.
Of course it is safer to keep things saddled at every stage. I'm just guessing the starting demands of this power supply stage will be around double because; the capacitors will be drawing a huge amount of current for a fraction of a second at start up and the amp may be turned on with the volume already at listening levels.
Kind of why I am softly pushing for fusing the supply rails. If you try and protect the whole system you still need to have the line fused at double expected output to allow for start up. If the line is fused at double expected steady state output, you will have enough juice to steady state fry the amp.
It would probably be a better design choice to have a 1 amp slow blow fuse on the line that would live past the start up surge, still give OK protection for a catastrophic failure, and offer some protection from knuckleheads that turn the volume up to eleven. Six of one, half dozen type choice IMHO. Any fuse is better then no fuse. Multiple fuses at different stages is the best protection.
I'm having trouble d/l your pictures but thank you for the effort. I love seeing pictures of peoples' work.
I thought I should explain a bit about why I think the supply rails should be fused. The analogue of a capacitor being a storage device like a battery is a good one in this case. Just imagine each of your capacitors is a 35V<~where you will be operating at> battery capable of delivering 1,000 amps for a fraction of a second. Three times the voltage of a car battery and double the amount of amps! Given that failure mode of transistors/amps is frequently a dead short to ground, do you want that kind of current flowing through your system.
Ditto for fusing the speakers. As the builder you know exactly what each part is capable of. You may want to move your system to another room and just use some 30 Watt speakers. You will know not to turn the system up because you could destroy the speakers, but nobody else will. Same holds true if someone decides to have karaoke party and borrows your amp. They may hook it up to 200 Watt speakers and some knucklehead will smoke the amp turning it up.
Unless you live in a cave there will always be a chance of someone fooling with the amp. Worse case scenarios have happened to me. One time a drunk was so plastered they couldn't hold their glass of beer upright. I said "Hey, your spilling your beer!" and they responded by pouring their beer into my stereo! Mean jerks just look for the things you hold valuable to express themselves.
I thought I should explain a bit about why I think the supply rails should be fused. The analogue of a capacitor being a storage device like a battery is a good one in this case. Just imagine each of your capacitors is a 35V<~where you will be operating at> battery capable of delivering 1,000 amps for a fraction of a second. Three times the voltage of a car battery and double the amount of amps! Given that failure mode of transistors/amps is frequently a dead short to ground, do you want that kind of current flowing through your system.
Ditto for fusing the speakers. As the builder you know exactly what each part is capable of. You may want to move your system to another room and just use some 30 Watt speakers. You will know not to turn the system up because you could destroy the speakers, but nobody else will. Same holds true if someone decides to have karaoke party and borrows your amp. They may hook it up to 200 Watt speakers and some knucklehead will smoke the amp turning it up.
Unless you live in a cave there will always be a chance of someone fooling with the amp. Worse case scenarios have happened to me. One time a drunk was so plastered they couldn't hold their glass of beer upright. I said "Hey, your spilling your beer!" and they responded by pouring their beer into my stereo! Mean jerks just look for the things you hold valuable to express themselves.