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stan001
post Oct 23 2010, 01:45 PM

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Sorry if this is off topic, I would like to seek some advise from experience electronics/audio people. smile.gif

I am trying to make a simple DIY Oscilloscope using the soundcard line in as input source from the article below :-

http://www.ledametrix.com/oscope/index.html

From his wiring for the probe, what are the RISK of blowing up the soundcard / PC motherboard from over current / voltage ??

Attached Image

What is the max voltage / current can the Line In take and how to filter / protect them from over current/voltage ??

I am using it mainly to test/troubleshoot electronic circuits DC 12V or below with the following software :-

http://www.sillanumsoft.org/prod01.htm

or

http://www.zeitnitz.de/Christian/scope_en


Thank you






stan001
post Oct 23 2010, 11:39 PM

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QUOTE(LittleGhost @ Oct 23 2010, 03:02 PM)
To get the absolute specs, you need to refer to the datasheets of the ADC stage of the sound card.

the resistor setup is to current limit and provide okay-ish input impedance for the load. I think all is well if you prevent too much current leaking towards the input of the Soundcard. Need to do your maths here.

Basically an ideal OSK when measuring voltage has very very high impedance (so that input current becomes moot).

I don't know what you're fixing but, something that samples at 44.1KHz isnt going to capture oscillations occuring at 1MHz and above.
EDIT: I see you're also into arduino. Any reasons for going with the Arduino route? I'm trying to design a high end attenuator + IR RX/TX control + LCD system for amplifiers but I don't know what chip to use.

My only experience is C Language + 8051 based microcontrollers, so I think I'm fine with anything that works with C.
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Thanks for the reply..

I just want to use a PC Oscilloscope to do basic RF troubleshoot and learn more about the electrical signals...

Got a pair of 315Mhz RF Transmitter and Receiver.. could not get it working with Arduino... and cannot "see" RF so need an DIY oscilloscope to "see" the RF. Will I be able to "see" anything since the soundcard is only at 44.1Khz ??


I use Arduino bcos of a few reasons :-

1. It is easy for beginners / noob like myself ( I'm a very new to electronics ) cos it was designed for artists/fashion designer

2. It is open source hardware ( parts is easily available here in Malaysia ), read my blog for details..

3. Lots of vendors selling Arduino here in Malaysia

4. Lots of libraries and a very large communities worldwide ( http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?board=projects )

5. The language is C like... make me feel at home.. (other MCU lang looks like assembly lang... yucks!!! )

6. I hv figure out the LCD portion, the IR remote RX/TX should be easy, lots of articles online using Arduino


What is a high end attenuator ??

I'm currently using a TA-2020 MKIII made by one of the forumer here, just using it, did not modify it or anything... just use it to drive my bookshelf speakers...

You can read up a very good tutorial here :-
http://www.ladyada.net/learn/arduino/

IR remote stuff here :-
http://www.ladyada.net/learn/sensors/ir.html

You can buy an Arduino locally in KL at : http://www.homebrew-tech.com/








stan001
post Feb 26 2011, 03:00 PM

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QUOTE(mengsuan @ Feb 26 2011, 12:06 PM)
Offtopic: I just had a nightmare that my DIY amp and cable broke. blink.gif
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Check yr blog, all yr photos there is with a "frozen frog" image...

I think you need a better image hosting service...


stan001
post Mar 1 2011, 06:14 PM

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QUOTE(mengsuan @ Feb 26 2011, 03:52 PM)
The imageshack crap affects Lowyat.Net as well. It will show up if you have registered an account with imageshack. I have also wrote to imageshack to whitelist my blog URL. Quite disappointed with imageshack this time.
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[sorry, off topic]
If you are on blogspot, why dun u just upload pics directly to blogspot, image won't go missing...
Nowdays so many image hosting to choose from anyway...


Back to the main topic...

Attached Image

I built my very first DIY "audio" electric guitar headphone amp using LM386 for my 12 years old nephew.

I just blindly follow all the circuit from the net...

user posted image


Since it is for elec guitar with lots of distortions, don't think it is audiophile quality.. hehe

I had a switch to switch between clean ( 10nF caps ) and distorted ( 10uF or 22uF caps ) sound...

I later soldered everything into a perfboard with 2 pot to control the volume control and distortion level and put everything into a smalll project box with a 9V input connector... ( forgot to take pictures )

Making the casing is really challenging with all the drilling, mounting the board & pot and measurements....


The feedback from the customer ( my nephew ) says it sound "quite" good and the parents are happy cos no need to hear
all the noisy guitar sound when he is practicing..


A few questions that I don't really understand, how come changing to higher value of the capacitor, it makes it more distorted sound ( which is a good thing in elec guitar )...

Any suggestions to improve this amp ?


I'm still a newbie in electronics and I self taught myself in electronics with no background or studies in electronics ...



This post has been edited by stan001: Mar 1 2011, 10:58 PM
stan001
post Mar 4 2011, 01:43 PM

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QUOTE(Jackygwh @ Mar 4 2011, 11:43 AM)
guys... anyone know where to buy autoranging multimeter? pro's kit ?
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Try Jalan Pasar...

What the budget & accuracy do you need ?

Any extra functions needed like temp sensors, frequency measurements ?


Reputable brand : Sanwa ( Japan ) or Fluke ( US )

Good brand : Pro's Kit ( Taiwan )

Okay brand : Sunwa ( China )



The price all depends on the "accuracy" of the readings and the "quality" and "design" of the parts used inside the meter.

This post has been edited by stan001: Mar 4 2011, 01:44 PM
stan001
post Mar 17 2011, 09:50 PM

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QUOTE(Cosef @ Mar 10 2011, 09:15 AM)

Placebo effects are the one that believe next year the earth will doomed after watching 2012.  laugh.gif
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Yr concept about placebo wrong la...

Placebo effect is when we were "told" a special pill can make us smarter/stronger/bigger/happier/whatever when the pill actually does nothing ..
we just "feel" different bcos of taking the pill..



stan001
post Jun 21 2011, 11:54 PM

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QUOTE(xowangzi @ Jun 21 2011, 10:49 PM)
Hah, cool ~ Im now only 16 wink.gif
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Resistor colours got online calculators

http://www.dannyg.com/examples/res2/resistor.htm

This is a good books for electronics :

http://www.amazon.com/Make-Electronics-Dis...t/dp/0596153740

From basics components, to soldering to integrated circuits (Chips)...

Or free online resources on electronics on my bookmarks :-

http://www.ibiblio.org/kuphaldt/electricCircuits/index.htm
or
http://www.allaboutcircuits.com/
stan001
post Oct 28 2011, 10:25 PM

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I won't give u an answer but here are the links to four of the datasheet you mentioned in yr questions..

Read them and compare their specs, application usages...etc..

I think the 3 op amp you mentioned are not so suitable for professional audio applications...

Aztronics seems to sell a few types of audio op amp...
http://store.aztronics.com/index.php?route...ategory&path=42

Datasheets ...
http://datasheet.octopart.com/OPA2227PA-Te...heet-149651.pdf

http://datasheet.octopart.com/MC1458N-STMi...heet-640151.pdf

http://datasheet.octopart.com/LM358N-STMic...heet-529748.pdf

http://datasheet.octopart.com/TL072CN-STMi...sheet-42733.pdf


stan001
post Oct 30 2011, 11:40 PM

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QUOTE(BanG_DeaD @ Oct 30 2011, 12:48 PM)
Oh.. ok.. so my 'from source' and 'to circuit' should switch places...
tq... biggrin.gif


Added on October 30, 2011, 3:15 pmI currently have a unregulated AC-DC adapter which have a 12V output (i tested it with a voltmeter) and is 500mA max. Can I plug this to replace the 9V battery (using TLE2426) so it will provide +-6V ?

I know I'm asking a lot of question.. That's because i'm a newbie...  blush.gif
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No worries, we are once a newbie at one point or another...

Short answer, NO, the adapter ( unregulated AC-DC adapter ) can ONLY supply +12V , not the -12V needed by the op amp..

Long answer, you would need some power supply unit that can supply BOTH + and - voltage.. one I can think of is the PC power supply, but I m not sure if these noisy switching power supply is suitable for audio circuits..

Read the below for details..
http://tangentsoft.net/audio/opamp-ps.html


stan001
post Nov 2 2011, 12:15 AM

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QUOTE(BanG_DeaD @ Oct 30 2011, 11:47 PM)
no no no.. i dont mean i straight plug the adapter to cmoy.. i mean, i use the adapter to plug to the rail splitter (tle2426) then only to cmoy.. so instead of the 9v battery pluged to the tle2426, i plug the 12v to the tle2426.. the only thing i worry is the 500mA ... the adapter can use right?
user posted image
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Oh.. i c..

Some of the 12V adapters ( usually with a 220V to 12V transformers inside ) , the voltage can fluctuate between 11-17V or more... test it with a multimeter and "see" the voltage goes up and down...

So the other replies suggest that you put a voltage regulator before the TLE2426 to get a stable voltage.. LM7809 will give you a 9V input into the TLE2426.

goto http://octopart.com/ and search for the datasheets...


I would like to guide you when giving an answer.. so next time u can ALWAYS refer to the datasheets when looking at the IC specs..

According to the datasheets, TLE2426 : http://www.ti.com/lit/ds/symlink/tle2426.pdf

Page 4, absolute max rating is 40V, output is half of input voltage.. so u r "safe"...


I assume the input IC is OPA2227, the dahasheet : http://datasheet.octopart.com/OPA2227PA-Te...heet-149651.pdf

Page 2, OPA227 is +/-5V to +/-15V and max input voltage is +/-18V..

So you are in safe range too..




stan001
post Nov 8 2011, 05:38 PM

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Do post some pics of yr project once it is done...

Where do u order the TLE2426 and the Op Amps IC ??


stan001
post Nov 15 2011, 12:19 PM

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QUOTE(BanG_DeaD @ Nov 14 2011, 10:58 AM)
Had some problems with my Cmoy on a stripboard vmad.gif , so I decided to make another one using a breadboard and it worked.. Then, I soldered all the components on a new stripboard and still had problems  rclxub.gif . After touching the circuit, shaking up and down, moving here and there, and brushed the flux off with a little bit of water; it finally worked.  thumbup.gif I abandoned the TLE2426 as it was causing me problems too (bad soldering) and used the resistor divider instead (470uF). This Cmoy uses a TLE2072 op-amp, 0.15uF input caps, 2kΩ resistors (gain 6), 2x10kΩ Pot (each controlling one channel). My Cmoy can be powered either by battery or AC-DC adapter (controlled by switch). The AC-DC jack on the Cmoy is connected to the resistor divider through a Voltage Regulator which throws 12V as the output while the battery jack is connected straight to the resistor divider. Enjoy the photos...  rclxm9.gif
Nicely done.. rclxms.gif rclxms.gif rclxms.gif

A few comments...

1. Why didn't u use the same DC plug for both AC Adapter & 9V battery.. and save some components ( I guess u didn't buy an extra DC jack for the 9V snap on )

2. Use single-core wires for components on the prefboard, easier to solder ( I guess you didn't have single-core wires during yr constructions stage )

3. I notice the wires leading to audio in and out is different sizes joint by heat shrink wrap... this is not good for impedance matching, just use a same type of wires across... from a thick wires to thinner wires , the signal might change a bit..

How the sound quality compared to without the amp ?



stan001
post Nov 16 2011, 11:05 AM

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QUOTE(BanG_DeaD @ Nov 15 2011, 03:59 PM)
I'm still very happy with it as this is my first project  thumbup.gif .. About sound quality, i don't really know how to describe  shakehead.gif .. I think the bass and soundstage are improved ..  cool.gif
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I think you did a very good job for first attempt.. rclxms.gif rclxms.gif


Added on November 16, 2011, 11:13 am
QUOTE(BanG_DeaD @ Nov 15 2011, 04:56 PM)
I like my wires  tongue.gif  No one is gonna open and see it when listening to it haha  icon_idea.gif Actually all my problems were noises.. I manage to get rid of the noise on my final product.. I only have a slight noise (only at high volume, which i don't really reach that high) when it is powered by the ac-dc adapter.. The battery power is silent  thumbup.gif
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Pls look at this link about bypassing & decoupling... if the input power is not clean ( too much ripples in voltages ), it might affect the output of the op amp signals too...

http://www.williamson-labs.com/480_byp.htm

Something for you to think about with those long wires...

I measure AC Adapters ( heavy ones with transformers inside ), their voltage level do fluctuate quite a lot....put a few ceramic capacitors to smoothen the voltage level...

If your multimeter can measure relative voltage, hook it to the output of the LM7812 and check for voltage ripples... put some 100nF ceramic capacitors to smoothen it a bit... and measure again...


All the grounds should be connected together.


This post has been edited by stan001: Nov 16 2011, 11:13 AM
stan001
post Dec 6 2011, 02:41 AM

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QUOTE(beggarmaster2000 @ Dec 3 2011, 12:18 AM)
for such battery 7.2V you can try.... user posted image
47/100uf x5
470/1000uf x3
0.22/1uf x2
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BM2000, cool.. I think I hv seen this chip before in my very old Sound Blaster soundcard that was still using thru-hole components...



stan001
post Dec 22 2011, 08:25 AM

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This fellow totally changed the IC amp inside his speakers... dead-bug style..

http://www.hackvandedam.nl/blog/?p=351


stan001
post Feb 2 2012, 12:17 AM

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This online store sells some audio op amp ICs..

http://store.aztronics.com/index.php?route=common/home

stan001
post Sep 28 2012, 01:01 AM

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Just sharing..for those that are new and not aware, you can goto ti.com and Order Free Samples and they will FedEx those samples to you for FREE...

The OPA2132P/PA are listed as free samples... choose the DIP version...

For justifications, just mention you are testing/designing some audio products,etc...

Ordered on 23/09.. approved and shipped out on 25/09 and ETA from FedEx will arrived on 28/09...

Other Free Samples...
http://www.ladyada.net/library/procure/samples.html

stan001
post Oct 8 2012, 03:45 AM

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Where to buy 0.1uF pp film cap & audio volume pot in Jln Pasar ?
stan001
post Oct 23 2012, 07:27 PM

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QUOTE(LittleGhost @ Oct 21 2012, 09:30 PM)
Not sure if anyone's interested, but...
» Click to show Spoiler - click again to hide... «

Teaser on a fully Discrete Amplifier I'm working on.
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Off topic...

Are u using the signal/freq generator to test the amplification / signal response by the amp u r building ?

This post has been edited by stan001: Oct 23 2012, 07:28 PM
stan001
post Nov 2 2012, 11:09 AM

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Found this see-thru "crystal" CMoy amp with instructions on how to build it...

http://runawaybrainz.blogspot.com/2012/04/...-headphone.html

user posted image





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