Well, if you used the High Efficiency circuit (Fig 6) from here:
http://www.electroclub.info/invest/tda7294/TDA7293.pdf
You would not need to worry about having a supply larger than +/- 29V for your 4R load.
If you already have a cct then a 21-0-21 Vac would meet your limits.
Or you could use the 24-0-24Vac and use linear regulators to keep it to 29V max.
http://www.electroclub.info/invest/tda7294/TDA7293.pdf
You would not need to worry about having a supply larger than +/- 29V for your 4R load.
If you already have a cct then a 21-0-21 Vac would meet your limits.
Or you could use the 24-0-24Vac and use linear regulators to keep it to 29V max.
Well, if you used the High Efficiency circuit (Fig 6) from here:
http://www.electroclub.info/invest/tda7294/TDA7293.pdf
You would not need to worry about having a supply larger than +/- 29V for your 4R load.
If you already have a cct then a 21-0-21 Vac would meet your limits.
Or you could use the 24-0-24Vac and use linear regulators to keep it to 29V max.
i'm using pcb not from datasheet.and what if i use 18-0-18 or 17-0-17 will it be to low?or it still be good
The thing is i now have a big old russian transformer with 2x27v secondary voltage after brigde rectifier i get 2x24v and after 2x4700uf caps soldered on wires i get 2x38v i builded this power supply for tda7293 at 8 ohms load now i have concert speaker witch is 4ohms so i want to rebuilt power supply that tda could work with 4ohms load.With mosfet regulators i can get voltage dropped down to 2x30v dc, one person at other forum gave this schematic http://i.imgur.com/KUsMqlu.gif its cheaper than buyin a new transformer but i thinked that building the voltage regulator would be bad as its have to drop 10v or so on each rail with 4A current is i use 80% of tda volume so the regulator mosfets would heat a very lot, and for that i need big heatsink,my amps box is already very big weight is 6kg (old transformer - 5kg) so i think i buy the new transformer but also that person said that seconady ac * 1,35 = voltage i get after capacitors is it true no matter what capacity capacitors i use? 4700uf or 10000uf e.g.Well, if you used the High Efficiency circuit (Fig 6) from here:
http://www.electroclub.info/invest/tda7294/TDA7293.pdf
You would not need to worry about having a supply larger than +/- 29V for your 4R load.
If you already have a cct then a 21-0-21 Vac would meet your limits.
Or you could use the 24-0-24Vac and use linear regulators to keep it to 29V max.
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i mean geting atleast 60w of amplifier power, will transformer like 200w 2x17v be good with 2x10000uf caps?
hello again my friend gave me toroidal transformer 200VA 24-0-24 and after bridge rectifier and 2x10000uf caps i get stable 35v so if i apply thoose 35v to tda7293 at 4ohms load will it blow up? on some forums i read that at this voltage and 4 ohms load its working but also heating little bit more
is toroidal transformer 2x24v 200VA be good with 2x10000uf 63v cap's in power supply for tda7293 at 4ohms load? in datasheet is specified that at 4ohms load - 29v is max voltage. so what voltage of traansformer is needed that after two 10000uF caps it not exeed 27-29v?
2x24Vac is +/-32Vdc!!
24x1,33=32!!
Check with a multimeter.
(Or you could use the 24-0-24Vac and use linear regulators to keep it to 29V max).
Mr DUG,
that linear regulators? give the schematic (circuit)?!
thank you!
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checked already and multimeter shows 35v...2x24Vac is +/-32Vdc!!
24x1,33=32!!
Check with a multimeter.
i thinks he's talked about this chematic:
zener diode's - 2w and resistor's 2-5w
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24-0-24 V trafo will give 24 x 1.414 V - diode drops - ripple - trafo drop on load.
No load will have no diode drop or ripple or transfomer drop and = +/- 33.94 V if your mains is at the correct voltage.
With the circuit connected and no signal you might get around +/- 31 V dc. With a transformer with 10% regulation ( at specified load) you might have about +/- 25 Vdc at max signal on the load. Toroidal transformers can have better regulation like about 5 to 7 % for smaller transformers.
No load will have no diode drop or ripple or transfomer drop and = +/- 33.94 V if your mains is at the correct voltage.
With the circuit connected and no signal you might get around +/- 31 V dc. With a transformer with 10% regulation ( at specified load) you might have about +/- 25 Vdc at max signal on the load. Toroidal transformers can have better regulation like about 5 to 7 % for smaller transformers.
Looks like many builders forget that all amplifiers generate heat in their output stages. With higher supply and lower loads you get 'more output power' AND you get 'more' heat in the output stage. So why should one be surprised that it " heats up more " than with a lower supply or 8 ohms load ? Even classD amps generate heat because no amplifier is 100% efficient. You need to use sufficient heat sinking to ensure that temperatures stay within limits under all load conditions.
You might also take note that a +/- 35 Volts supply will most likely drop to less than +/- 29 volts with a 4 ohm load when driven hard. This limits the output power into 4 ohms and will not be just double what you get on an 8 ohm load.
This could be improved with a bigger transformer and larger supply capacitors. However the supply can end up being several times more expensive than the rest of the amp.
I read through the data sheet you linked and all I could find was places where they said the chip is more efficient, no graphs or numbers.
If you take them at their word 'the device is more efficient then other amps' you are good to go with the toroidal coil.
The chip is designed to use up to +-50V so you are in a safe with the voltages you will get. No need to put in regulation, just the filtering and any safety measures you want to use like fuses. Gost22 & Ashok's calcs are good. I would double check those 10000 uF caps to make sure they are rated at least at 35V and preferably 50V. If your caps are 35V, never plug in the power supply w/o a load. Really, it could be something as simple as a resistor or light bulb of suitable voltage and wattage.
You may want to make the power supply and amp on separate boards. They are both going to be pretty nice. If something happens to one, ;[power surge takes out the transformer, shorted speaker], the other board will still be worth using in other projects.
i know that i dont get more than ~70w power on 4ohms load, and i know that it heat more,and it will not drop because i have connected 60w light bulb on vs+ and vs - to measure voltage drop with 60w load, and voltage was 70-71v on vs+ and vs- so its = 35v on vs-/gnd and vs+/gnd
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caps are rated at 63v and power supply board is separate from amp's board
for safety i better ask ten times than blow up in one secondand on elliot's page he's saying that:
The TDA7293 specifications might lead you to believe that it can use supply voltages of up to ±50V. With zero input signal (and therefore no output) it might, but I don't recommend anything greater than ±35V if 4 ohm loads are expected, although ±42V will be fine if you can provide good heatsinking.
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I am not sure what you mean by this. A 60 watt light bulb meant for mains use will not be a 60 watt load at 70 volts ! The bulb heats up at mains voltage and has a different resistance compared to what it is at 70 volts. Measure the dc current through the bulb and V/I will give you what it's resistance is. Might be several times 4 ohms. I'd hazard a guess it could be 100 to 200 ohms or more at 70 V ! In fact we would like to know what you find !
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so i think that light bulb method is for testing the power supply if its working yes?
and if i connect 2x35Vdc to tda7293 at 4ohms it will not explode? that's i want to find as members say that voltage will drop then i turn on amp, and there is one fact that - one of my tda7293 exploded with 41Vdc at 8ohms load (anomaly) and for other it was my fault - reversed polarity for vs- and vs+
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but i want to remodel it to work on 4ohms load and my friend gave me toroidal transformer (for about 20 $) 24-0-24 voltage for that project so after diode bridge and two 10000uf/63v caps i get 35Vdc with no load, as is posted by Gost22 so can i turn on tda amp with that voltage?or should i do something to drop voltage to 30v with no load
You can use your 24-0-24 V transformer . Your amp will not break down. Just connecting a 4 ohm load with a +/- 35 V dc supply will not cause any problem. If you had a 'regulated' FIXED 35 V supply you would have a problem ONLY if you drive the amp to full output.
But here you have a transformer and 10,000uF caps per rail. That voltage will 'drop' as you keep increasing the output level till the output clips. At that point the supply would be +/- 30V or less. In any case you would also know as the heat sink would get pretty hot . You should have no problem as long as the heatsink is sufficient. You would know that if it get's too hot!
But here you have a transformer and 10,000uF caps per rail. That voltage will 'drop' as you keep increasing the output level till the output clips. At that point the supply would be +/- 30V or less. In any case you would also know as the heat sink would get pretty hot . You should have no problem as long as the heatsink is sufficient. You would know that if it get's too hot!