wuemura

Hi audioguru, I've checked and re-checked the new connections but some how made the opamp's to oscilate, pins 5, 6, 9, 10, 12, 13 has a clear beep on it and the output also. The power amp blocks had a small "buzz", removing the supply jumper away from the input pins solve this issue. No problem, i will rebuild it. Thanks

Hi audioguru, I've changed everything values, tracks etc. When all is ready and i turn it on i could not hear any music at all, but, i could hear a clear, loud, no noise or distortion 1Khz beep ;D ;D ;D I will do this from ground zero all over again in separated boards, one for the main input signals and filters and other just for the TDA2005. Thanks, when is done i come back here to post the schematic.

Hi Audioguru, I did some more tests with only one stage, all other stages are out, injecting signa at R36 with all the changes, the sound is like AM radio with noise and stuff, using a 470K in R68 and injecting sound there still the same, lot of noise with sound. Removing this opamp and injecting signal at the same place (R68) i got a cristal clear sound, changing the TL074 make no difference. Do you think it could be ground?? Or oscilation of the TDA2005??

Something is wrong, i removed all the opamps and the TDA2005 output is quiet, but still if my hand is near the caps it generates alot of noise. If i touch the 2.200 caps i can hear radio.... I will do it all over again. Any sugestions that i should follow to do pcb layout and avoid this noise power amps have this problems?

Hi audioguru, I've done the changes, but the circuit start to make sound like a fart ;D

Hi audioguru! I will try your changes :D Thanks

Hello guys! I want to use a mid-range and tweeter to make a center channel in my car, so i choose to use the TDA2005 plus an active crossover. When i turn the circuit on it has a static noise like, sound like a pink noise to me. So i remove R66/67/68/69 to isolate both circuits, analysing the filters all sound OK, conecting the speakers at the output, silence but looks like the circuit is too sensible if my hand is near, injecting RCA audio signal over C21/22/23/24 the speaker plays at full volume and no quality at all, there is this static noise with it, in small proportion but it was there. Reconecting R66/67/68/69 and grounding the signal with a 100K resistor at GND or AGND make no effect at all, it just get worse. Changing R54/55/56/57 to 2.2K the circuit is less sensible to hand movement, sound much better, but do not solve the static noise :( Board: Schematic: Thanks PS: I could not upload the pictures using the forum.

Just passing by to upload the last changes, board design, if some one decide to build the project.

Hi audioguru, it was a high resistence choke and was the cause of the problem. The LM317 only get burning hot when i set the NET-MD/Walkman to charge the battery because of the current to do it. I did not build this to charge nothing but is working, with a small heatsink it will not shutdown, the circuit can handle it fine, i can full charge the bateries without problems. Just playing MD or cassette it doesn't even get hot. Thank you.

It was Ldanielrosa. Mine some times made the led REG flash like a HDD everytime the MD lenses was moving. I just remove the choque, add jumper and its working fine, the LM317 just get a bit hot, it will get burning hot when is chargin the MD player batteries.

I've found the problem, it was the choke but without the choke i got engine noise, to solve that i add a 1R between the my board and the device. NET-MD and Walkman working fine!

Hi audioguru, The walkman that i use is the old SONY WM-FX822, here there is a nice picture of it: http://www.geocities.jp/sony_transistor_radio/walkman/_index.html It works with one AA battery and gives a nice 8hrs non-stop playback (cassette) and a few days with radio. It uses only about 10ma to operate, about 200ma to work (cassette) and the worst case when you do a reverse is about 368ma. The LM317T is rated to handle 1.5A right?

I never use the LM317 and this was the first time, i have a NET-MD and old Walkman(cassette) that i want to use in my car, the NET-MD uses 3.0V and the walkman 1.5V, they need about 200ma to work. The thing that i've noticed is that the output of the regulator oscilates too much, at first i calculated Vout to be 3.05VDC but the voltage drop at use was 2.98VDC, so i recalculate the values to give a 3.20VDC (3.23VDC). The regulator is a LM317T(1.5A) and dont know why it can't handle this devices, the walkman works fine with radio, but do not work with cassette, when the motor start to run the REG led start to blink.

I don't think that this sound stupid. It needs AC because is the principle of his work. I think that this solution comes with a complete package, not just the swing motor, if some one get only the swing motor, without the controlers, this sound stupid to me because it's the same if you buy a chevy car engine to adapt in a Volkswagen Beetle without the central unit, electronic sensors etc, and say "it just need fuel to work. I was googling around and have found that this swing motor is used by some car manufactures in a eletric air conditioner, the principle is the same, but you will not connect the compressor at the engine, so it will not rise your car fuel consumption.

At the link they say: Principle When an AC current is applied to a coil placed at right angle to the magnetic field, a thrust occurs according to Fleming's left hand rule. This thrust is directly applied to the piston, which then performs the compression and intake cycles. If this swing motor works with AC, read this at the same page: http://www.sawafuji.co.jp/english/tech/dd.html In DC-DC converter, a DC voltage is first converted to an AC voltage using semiconductors, the resulting AC voltage is changed to a certain AC voltage with a transformer, which is then converted to a required DC voltage again. Look at this page: http://sound.westhost.com/project89.htm Is a switching power supply, before the "Ultra Fast Bridge" you have AC voltage, the problem is that you will have to build your self a transformer to output the 24VAC you need and to work with the 4A. But i don't think is just "plug and play", because at the sawafuji page you can read: ・Inverter control In order to obtain the maximum efficiency using the resonance phenomenon of a spring, it is necessary to carry out the precise frequency control. I've never worked with this type of motor, so i don't know if you simple feed this with 24VAC will work or if it need something else.

For thouse interested in design your own sallen-key filters here is a papper from TI (Texas Instruments) that will take you there in seconds: http://focus.ti.com/lit/an/sloa093/sloa093.pdf Very easy, you just need to work your math. ;D

Here are the changes made, sounds good, testing songs with heavy and deep bass the ambience channel is stable.

Here are the schematic for the Sallen key filter set for the same 72Hz and Q of 0.5, i will build this in a separate board and play with Q latter.

Hi audioguru, I will do some tests with your sugestions and see what it does. Thank you.

Hi audioguru, This circuit was design to be used in my car, so i think i am safe from vinil and tapes ;D The idea is to kill thouse deep bass because it does no good over the ambience channel, i did generate a 0db sine wave from 50Hz to 100Hz and in the ambience channel it get only distortion, i did not go any further with this tests but around 560Hz i can completly remove any distortion over the ambience channel. If in you simulation it get's a flat response down to about 470Hz sounds good to me, because in my car i have a pair of 2-way components system from Diamond (D661a) and a pair of 125W JL subwoofers in a sealed box, the head unit has 4 outputs 2 output for front and 2 output for rear channels and a stereo subwoofer output, so inside the car the subwoofers will take care of thouse deep bass. This circuit is installed to work with the head unit rear channel only, the front channels are connected in a standard way so i can hear the effect behind me, in the voice channel i use a Alpine SBS-05DC. When all that stuf is set it gives a incredible sound inside the car, if you hear a live recorded CD it gives the effect that you are there, you can feel it. I'm open to sugestions, what can be done to increase the cut, for example, -12db or -24db and tweek this a bit more.

There is alot of circuit's over the net that does what you want. Here explain why it can't play mp3. http://www.hardwaresecrets.com/article/71 Many others... https://unstable.nl/andreas/cdromdiscman.html http://www.sorgonet.com/trashing/ComputerAudioCDCarPlayer/ http://www.codepuppies.com/~ben/sens/pic/mp3/ This is kit you can buy: http://www.pjrc.com/ Many more over the internet, google for it.

Hi audioguru, Did a few more experiences with the circuit and have found a document that show me part of the solution for the problem: http://tangentsoft.net/audio/hs-opamp.html Paying close attention to the distortion it has to do with the bass of the sound, removing R5/R22 and replacing with a 120K trimpot to adjust the fase and gain, as i reduce the effect the sound was becoming more clear and the distortion was the booming of the bass. The problem is that if i remove the distortion, the effect got killed but if i increase it so the distortion. Analyzing the bass part of the song the problem was a frequency between 52Hz and 71Hz, the solution was to add a simple R/C high pass filter at the input. I set the filter to 72Hz with a 220nF with a 10K resistor grounded, that gives me a 6db per octave, calculations gives a 72.34Hz cut and a error of -0.07. It worked fine, did not kill all the distortion but is much better than before. In respect of audioguru golden ears i choose a real music, with lots of melody and high notes to test and hear if there is too much changes at the output and how the notes above that get affected. The music is "The Winner Takes It All" from ABBA. http://www.sendspace.com/file/iwlms4 Is the same deal, left channel is voice and right channel is ambience, play with the balance to hear what each channel is doing. I change the configuration of IC3B/C, for now it has the gain of 1, latter i will try a active bass boost at that frequency range and made a few more tests to see if it is necessary bost the bass or not.

Thank you, i will fix that ;D

Thank you audioguru. Any light on the strange distortion? Tell me something, if you run the tests again with some capacitance load wht and without the buffers, will the performance be the same? Thank you again!

Hi audioguru, I dont know if "cracking" was the correct name of that but if your hear only the right channel you will listen something "cracky" or "cranky" distortion, i dont know the exact name, sorry. The strange is that distortion is coming from R5 and R22, looks like a "Feedback Noise"? Yes, they are ambience channels, one is L-R (L channel) and the other is R-L (R channel), when this two are connected + the standard L and R channels inside the car it gives the effect of 360 degrees rotation if you build a "stereo rotation effect" in Adobe Audition, if you record a train passing by and apply the stereo rotation effect you will have the impression that the train running in a complete circle inside the car, very nice. Together phase analysis show a -180 degree phase shift. But what is very nice about it is that when you turn it on, since we are getting a -180 degree out of phase from the original sound, they cancel each other right? If you put a CD with empty tracks and play it inside the car you can feel a really strange silence, is good to help relax when you are trapped on heavy trafic. The resistors was added just to do signal attenuation, the buffers IC3B/C (ambience channel) was added and so the IC2C/D (voice channel) because inside the car there is a 6 meter long RCA cable from the instalation point to the power amp so they are capable of driving long cables and capacitive loads from the power amp. What simulation program that you use? Thanks