wuemura

Hi Audioguru, Thank you! Back to design board.....

Hi Audioguru. 1) The first voltage divider is made to make the OPAMP work with non symetric supply, as you suggest me at the time to do it (R12/13 C5). The main problem that i've faced with this is the cross talking effect when, if, i dont use the other dividers (R17/18 & R32/33) maybe because the R5 (100K) at the pin 3 of the OPAMP, if i remove R5 the circuit doesn't work and if i join all at the same point i get this strange effect. So the idea was to isolate and avoid this effect. 2)Hahaha ;D No Audioguru, in fact, this is the same program from the same audio source, this is the main propose of the circuit, to use the OPAMP and make a calculation and reproduce only R - L as surround channel and R + L as center channel, this configuration is also know as Hafler Effect. It took me a long time to get to this configuration because the effect is not perfect, you get some "garbage" as a result if you play a bad MP3 audio for example, you can hear the compression artefacts mixed with what you want to hear. If you heard the sample, you will noticed that the vocal is almost gone and the background is almost intact and very clear, using some acoustic technics when used inside the car you will only hear the back ground and the vocal is completly removed making a very impressive effect. The configuration here with the CD4053 is made only to bypass the surround circuit since i have only one source of audio (my car head unit) and on power amp. But, thank you for the comment, if you told me that i was changing from two different sources i guess i'm doing a good job ;) 3) We will have to solve how to make only one bias point, if i bias the output using the same configuration will do the trick?? The 10uF capacitors play a important role at this circuit and i can explain why: a) My car audio system was build with focus on quality, so i use a pair of component speaker with a pair of passive cross over each component, a total of 4 passive crossover and a pair os 12' JL subwoofer. b) The signal is digitaly crossovered to not allow 120Hz frequency and below (my head unit is Pioneer DEH-9880BT), tests made with capacitors from 1uF to 4.7uF do a strange "buzz" when i turn the circuit off. c) Since i have subwoofer in the car is not interesting to me to make the surround channel reproduce low bass, and the second point is that part of the solution to remove part of the garbage from the surround channel is to not allow too many bass in the channel, including thouse 30Hz frequency. d) As part of the design, when the surround circuit is turned on it will not kill all the bass but also will not remove all, maybe allowing to pass from midle to high frequency (200Hz and up, sorry can't precise that information), this is good for voice, guitar, symphony orchestra or what ever you hear at the car. You will notice in that sample that the backgroung is pushed forward, mixing that with the full configuration of the car you will hear the voice on the front and that beat song at the rear. Fading away that little voice echo and pushing forward the background, since is playing midle range frequency and up you can pin point exacly that the backgroung music is coming from the back and the voice is coming at the front. There is another problem that i thought for a long, long time. The bias resistors are in a indirect way "mixing" the signals ( L + R ), when i say indirect is because is not my intention to mix the signal channels but also i can't make it without it. If a 1M bias resistor makes the 10uF charge 10 times slower, if i down the value from 1M to someting about 530K it will make the same capacitor charge 5 times faster, but also will also mix the channels evem more, correct? Thank you.

Hello guys, long time no see! I've done a audio bypass switch using a pair of CD4053 and a CD4049, the two 4053 are biased with 1M Ohm resistors at the input and the 4049 are build to generate signal to the CD4053. All works fine, no noise (thanks god) but when i change the switches i can hear a clear "pop". I was wonder if there is a way to smooth this "pop" sound when i change audio source. Here are an sample of the pop: Download Here is the picture showing the first version at the top and the new version with the bypass circuit. Thank you.

Sorry but that is not my page ;) Yes, i do use magazine paper in my printer, just cut the paper and glue or put some tape to fixate the page OVER the normal A4 printer paper.

Hello! I've done a few more boards using this magazine paper, and it works like a charm. I think i've about 30 or 40 boards every and each one perfect. Also works fine to make component map.

No more comments? :-[ Anyway, the project is fixed, 100% working and with no noise at all. For thouse that is looking forward to build this project for your car (trust me, you will not regret this!) here is the full schematic and board design. After you build and intall the circuit at your car, you will have to work with your fader or amp levels, with my Pioneer DEH-P6800MP i set the fader a +5 at rear. Enjoy! http://rapidshare.de/files/30660605/hafler-1.4.pdf

Problem solved, since the noise was coming from the ground i cut and isolate the ground from the input and output RCA and rejoined with a 10 Ohm resistor, no more engine whining thanks God! Because of the changes, the gain was reduced also, now i'm working out this issue changing the R5 100K (gain) to about 110K or maybe 120K. PS: I'm updating the final schematic.

Well, adding the resistor to the ground just make things worse it amplify the noise, the choke coil makes no difference, maybe reduce the noise a bit but do not solve the problem. Next move is to feed the circuit with symetric voltage from 12v from battery, so i came up with the design bellow. I have a small and old PC speaker that i dont use any more, it uses that wall adapter (9VDC 1A) and in one of the speaker box is using this circuit to feed some opamp's that there is no mark on it, than it goes to a very cheap speaker. One thing i know for sure is that this thing makes no noise at all, the wall adapter has only one transformer, two diodes and a small 470uF capacitor. The 100n capacitors was my idea. So what you think?

Much more information about ground loop can be found at this site: http://www.epanorama.net/documents/groundloop/

This book does not solve the problem but gives a lot of information about ground loop and how to make a clean instalation to prevent it. http://www.benchmarkmedia.com/pdf/caig.pdf The book is free, http://www.benchmarkmedia.com/caig/html/

Thanks MP, i wil take a look!!!

Hello guys. This is making me sad, the noise still there :-[ nyjumpee, no, the noise do not get worse with headlights on, night is better because is more quiet at night. But the effect is the same is like a whine/buzz coming from the engine and also changes with the RPM. And looks like my installation is ok because this noise is introduced in to the amp after i connect the circuit, without it, there is no noise at all. I'm just guessing but i have a felling that this noise is not coming from the 12v but from the ground... I will try two options... Supply-1.png I did made a headphone amp called Super Headbanger, with this i had a few problems with noise also, killing the volume i could hear a 60hz buzz in the headphone, adding a 10R resistor solve the problem, i will try the same with this one. Supply-2.png I will try to add the choke coil and see if the noise get better or worse.

Nice, i will make the same effect but for a break light for my car with very bright led's, but i will change some things to look like a normal break light (all led's on) and than after some time knight rider effect, you see here at Brazil we can't use any light effects outside the car, like flashes etc. Only Police, fire fighters, ambulance can use such a things.

I can't believe it, the guy who installed the device on my car was feeding the circuit with 12v from ignition (also know as REMOTE) not directly from the battery >:( In my car was made a specific design to distribute the voltage directly from battery to amps and head unit. The voltage from the battery goes to a distribution box, than to a filter responsable to kill any noise from the alternator, from there it goes to amps and head unit. The guy design the thing and the same guy screw up, does any body has a shotgun around? ;D Now the device is installed again with my supervision, looks like the noise is gone, but i will have to test it at night. Thanks again audioguru.

It changes its pitch with the revs of the engine, it should stop it but it still there. No, the zenner is fine, my car battery charges at 13.8v max, the zener never heat it up. I will make some more tests tomorrow and i will let you know.

By the way, the effect is AMAZING. If you are doing nothing and are searching for something to build, this is the one, incredible!!!! I'm using the Alpine SBS-05DC to make my center channel but with out it it will do the same effect. Here is some examples, but, hearing the effect is much better. Gnarls Barkley - Crazy You can hear the "uuuhhhhh" at the back of your car and the main voice in front speakers. http://www.electronics-lab.com/forum/index.php?action=pm 7 messages Cherish ft. Sean Paul Of The YoungBloodZ - Do It To It You can hear the "Hey, hey, hey" and others back vocals at the back, the sound (voice )goes front/back make an amazing ambient. JOAN OSBOURNE - One Of Us Guitar in front, drums at back, than the guitar goes to back and the main vocals go to front. Black Eyed Peas - Pump It The "ha, ha, haaaa" is very clear at the back, and main vocals at the front. Shows - ANY If you take an Elvis Presley live recorded Show, you can hear things that wasn't there before, like people talking at the back, people chating, walking, screaming and so on, making an incredible ambient! And oh yes, looks like you are in the middle of the show, Elvis vocals in front, back vocals, crowd and everything else at the back of your car. A MUST HAVE in your car!

Don't know, in my car (Fiat Siena) it doesn't start the engine if i disconnect the O2 connector.

Hello guys! After building the Surround sound for car and installed in my car i've noticed that there is a engine noise on the speakers, the noise increase decrease when i hit the throttle, i can hear the noise when the volume is down and the ambient is quiet other wise there is no noise, removing the circuit makes the noise go away. The first photo is the prototype board, and the second is the modifications that i've done over the original schematic. Thank you.

Yes, and the engine will not start.

Hello, i really dont know what type of O2 sensor my car uses, i know that is 4 wire type, looks like a cigar and has a hole in the middle. About printing, here is the tip, load the PDF in to Photoshop. In resolution set to 600 pixel/inch, grayscale mode, 16bit and remove (uncheck) anti-aliased option. Duplicate the layer, so it will became more dark, press CTRL+E to join this parts, press CTRL+A and CTRL+C, create a new layer for printing, press CTRL+N to create a new layer, select A4 paper type, resolution set to 600 pixel/inch, 16bit and transparent background and paste the design (CTRL+V). Duplicate the layer if you want one or more bord designs in on sheet, print the design, Photoshop will complain about the size, just ignore. You are done, the design will be printed at the correct size.

Today is a great day, there is no way to put in to words, to develop something and see it working is a great feeling. Since i was a kid and started with electronic at 6 years, we had a very difficult time, my family was very poor so i've never got the oportunity to go to college or learn english at a decent school, all that i know today was result of my own fight to get it and without or few resource. That's why i would like to thank this space and audioguru for his patience with me, some of you might think that this is too simple, but for a guy like me that has no graduation at electronics, is a great thing. Audioguru, i've done your changes but did not work the way it should be, so let it be man, the main part it's working. So here is the photo of the main board (i took that with my cellphone camera) Here is the circuit when you turn the ignition on And here is the baby working This circuit has no precision, but compared with professional equipament, the circuit will respond to very small variations from 0,1mv to more or less 1.4v max. This computers/equipament that mesures this oxigen sensor you see the changes as jumps. Later i will record a video with the circuit installed and working. Thank you audioguru. PS: The full schematic and board design is attached with this message, use it, make modifications, sell it i dont care ;D HallMeter.pdf

Hi audioguru, i've added resistors up to 1M and make not change at all, just a little shadow makes the led to turn off. And by the way, is the first photo-transistor that looks very much like a LDR to me.

Hi Audioguru, well i've done the changes but.... some how works. At normal day light the led bright is strong, but just a little shadow make the LED to shut down. :( Putting all back again, if i change the R9 to 100K the effect become a little more effective, but not that much. Increasing the resistor to 220k and so on, make no changes at all. If i change the transistor to BC327 or BD140?

In the light 7.6M, dark 0ohm

Hello audioguru! The circuit work in the reverse way, when is dark the led must bright more, the day light must make the led dim off ;D Changing the LDR with a 10k resitor make the led bright a bit, about 25% or 30%, shorting the connection make the led bright at 100%, when i say that it bright more i mean the full display. At your schematic i've noticed that you removed VR2 and VR3, VR3 is used to set the low level input and VR3 the high level. When you turn the device on the first led must turn on, if not, you ajust VR3. Injecting 1v DC at the input terminal the 20th led should lit and stop there, if not VR2 make the magic happens. So, looks like the circuit is working but not the way it should, so working with the 680r resistor or the transistor could make things working, right?