I use computer speaker amplifiers from external kits and automibile graphic equalizers for my preamp and equalization circuits. I may modify them to adjust the performance to my liking. The computer speaker amps usually have volume controls included--a plus. I have used an automobile graphic equalizer for equalizing my subwoofer by lowering the center frequencies of the slider adjusters. I soldered capacitors across the appropriate ones in the circuit to create the new center adjustment frequencies of 30, 45, 60, 75, 90, 105, and 120 hertz.
Japaneese transistors are designed for audio circuits to a very large degree since for the longest time they were way more serious about audio fidelity than US semiconductor manufacturers. So, yes, Japanese transistors are generally superior for audio amplifier circuits. The 2SC3281 and 2SA1302 are some of the best transistors for audio outputs.
COULD U SUGGEST ME A PREAMP SCHEMATIC?
WHAT DO U THINK ABOUT THIS CROSSOVER?
WHAT DO U THINK ABOUT THIS CROSSOVER?
An externally hosted image should be here but it was not working when we last tested it.
I am not really good in that area. It is just not interesting to me since I am not choosey about performance since midrange and treble is a part of music which is not exciting to me. As long as distortion is reasonably low and the tone has a pleasing balance, one circuit, preamp, or equalizer is as good as another
If I were to build a preamp, I would probably build it out of an audio amplifier IC like the LM3875. But I just find that it is easier to take open a low priced computer speaker and tap into that circuit by disconnecting the speaker and feeding out the speaker wires.
If I were to build a preamp, I would probably build it out of an audio amplifier IC like the LM3875. But I just find that it is easier to take open a low priced computer speaker and tap into that circuit by disconnecting the speaker and feeding out the speaker wires.
Hi! I've build the TDA7250 schematic with a tip142/147 buti hear alot of crackle.. maybe for alow ampère produced? or the fact that from the car radio i've a peak of 250mA as output? And another thing... I always see a capacitor at the input stage, what's it's sense?
And what's the difference (if there's one) between 18A and 18VA? And between 20W RMS and 20W?
And what's the difference (if there's one) between 18A and 18VA? And between 20W RMS and 20W?
The input of the amp circuit draws way less than 250mA. The problem would be something other than that. Maybe the problem is that you did not include the input capacitor, which is very important to shift the different DC voltge levels between the output of the car stereo and the amplifier input.
Check the voltage rails of the amplifier to see how well they are holding up. If they are sagging way down under the speaker load from turning up the volume, you will want to experiment with changing the transformer windings to get more power output. Try something like removing one winding from the primary and two from the secondary at a time, rechecking the performance of the system each time
18A means 18 amperes. 18VA means 18 volt-amperes which is usually the same thing as 18 watts. 20 watts implies an average of 20 watts or maybe in such cases like appliance power draw, the maximum. 20 Wrms implies that peak power is twice that--40 watts. If you wish to see the simple formulas concerning how peak voltage and wattage relate to rms voltage and wattage, look in an Electronics or Physics text book as I am not talented in Math
Check the voltage rails of the amplifier to see how well they are holding up. If they are sagging way down under the speaker load from turning up the volume, you will want to experiment with changing the transformer windings to get more power output. Try something like removing one winding from the primary and two from the secondary at a time, rechecking the performance of the system each time
18A means 18 amperes. 18VA means 18 volt-amperes which is usually the same thing as 18 watts. 20 watts implies an average of 20 watts or maybe in such cases like appliance power draw, the maximum. 20 Wrms implies that peak power is twice that--40 watts. If you wish to see the simple formulas concerning how peak voltage and wattage relate to rms voltage and wattage, look in an Electronics or Physics text book as I am not talented in Math
I've just check another unit (same model) SMPS and found that that particular diode is also very hot, so I guess it has been like that in the beginning.
Its unlikely to rectify more than 60v as the max voltage in the DVD PS is around 14v. Maybe its just too much current, but I tried to double up the diode and it didn't help. Maybe I should put in a heat sink.
Its unlikely to rectify more than 60v as the max voltage in the DVD PS is around 14v. Maybe its just too much current, but I tried to double up the diode and it didn't help. Maybe I should put in a heat sink.
Now that you mention it, there is a slight discoloration in the bottom of the board. Solder looks ok though.
There is some sort of feedback circuit connecting to this diode that goes through a pair of 1n4004 in series. I change this to ultrafast MUR160, do you think this will make a difference. Thanks for you help.
There is some sort of feedback circuit connecting to this diode that goes through a pair of 1n4004 in series. I change this to ultrafast MUR160, do you think this will make a difference. Thanks for you help.
And another thing.. i've meauserd the A at the output.. I've only 1.7A and that's natural since I use a 220v=>14V@1.6A transformer...
But i use a car battery (12V@70A!!!) is natural to have only 0.6A? What can be wrong? Or there's something to do to increase the A???
Thanx in advance to all!
But i use a car battery (12V@70A!!!) is natural to have only 0.6A? What can be wrong? Or there's something to do to increase the A???
Thanx in advance to all!
Hii. The buzz problem may not be solvable. It may be the same problem I had when I tried that SMPS controller. It may not be able to keep from shutting off the pulses to the transformer.
If that is the computer power supply core, I would expect you could get more than 14.4*1.6 volt-amps from it. If you are using a standard 50/60 hertz power line transformer, then I understand your problem.
If you are using a car battery, the current draw may be limited by the impedance of the circuit connected to its terminals. You might enjoy some research into many interesting things that can be learned in the field of Electronics. Start by browsing around on Google. It can be fun.
If that is the computer power supply core, I would expect you could get more than 14.4*1.6 volt-amps from it. If you are using a standard 50/60 hertz power line transformer, then I understand your problem.
If you are using a car battery, the current draw may be limited by the impedance of the circuit connected to its terminals. You might enjoy some research into many interesting things that can be learned in the field of Electronics. Start by browsing around on Google. It can be fun.
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