You don't scare me
Actually, I forgot to order them & only the ordinary ceramic types are available locally. I dont want to wait for another 15 days for it to arrive.
I'm more concerned from ckt. stability point , thankfully I don’t have golden ears to diff. between various capacitors.BTW I've read somewhere that SMD ceramic cap. are C0G only
Actually, I forgot to order them
& only the ordinary ceramic types are available locally. I dont want to wait for another 15 days for it to arrive.I'm more concerned from ckt. stability point , thankfully I don’t have golden ears to diff. between various capacitors.BTW I've read somewhere that SMD ceramic cap. are C0G only
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C0G/NP0 have better Tempco and Voltage coefficient. C0G vs X7R or less, generally C0G are made to a higher quality and can cause lower distortion due to the second factor. they are critical for timing and compensation circuits and have measurably lower THD depending on where they are used. no golden pinea arguments here, very objective.
but no, not ALL SMD caps are C0G, not in the slightest
but no, not ALL SMD caps are C0G, not in the slightest
I have a problem with my o2 amp,
I tried it with several sources, and each one gave the same result. The light comes on but there is no sound when the unit is switched on with battery power only. If you either start it on wall power and then remove the wall power, or start on battery power and then plug in wall power and remove it, then it runs fine on battery power. The key here is that it will run fine on battery power as long as it has been plugged into wall power, even for a moment, sometime after the power has been cycled. I can't see how any flaw with my several audio sources or a flaw with the batteries (I did try another set of known good batteries, by the way) could cause this strange behavior. I'm guessing that it might have to do with the power control circuit.
Any idea on where I should troubleshoot?
I tried it with several sources, and each one gave the same result. The light comes on but there is no sound when the unit is switched on with battery power only. If you either start it on wall power and then remove the wall power, or start on battery power and then plug in wall power and remove it, then it runs fine on battery power. The key here is that it will run fine on battery power as long as it has been plugged into wall power, even for a moment, sometime after the power has been cycled. I can't see how any flaw with my several audio sources or a flaw with the batteries (I did try another set of known good batteries, by the way) could cause this strange behavior. I'm guessing that it might have to do with the power control circuit.
Any idea on where I should troubleshoot?
the batteries are out of sync, if you have a standalone 9v charger, then take out of the o2 and charge them to full.. once you do that and put them back into the amp, it will work correctly..
next time don't run the battery down to a level where they are uneven
-joe
Please post well-lit, in-focus photos of your PCB from a few angles. That will help us immensely.
You will be amazed at what some people can spot on a photo!!
I will do that in a moment!
Both batteries are fully charged - Tested with a multimeter at 9.2 ish volts, and there is maybe a tenth of a volt between the two.
ramsfan6239's Library | Photobucket
There are a bunch of photo's, they will be the first 6 or so. If you need me to take more let me know.
-Tyler
There are a bunch of photo's, they will be the first 6 or so. If you need me to take more let me know.
-Tyler
Wow! I stumbled upon this one a few days ago and have read all 3000+ messages. Kudos to the great support you are lending to each other and to the newbies that are asking for help. I'll be one of those fellows in a month or so after I clear some other items off my desk first.
And especially thanks to the RocketScientist for the great effort he put in!
And especially thanks to the RocketScientist for the great effort he put in!
Hi guys, new to DIY. I ordered the kit from headn'hifi, I know how to solder and have all the right tools. BUT I can't work out how to sort and label all the parts I got and match them with the reference numbers on the BOM.
main problems is the tiny resistors. Do I really have to look at each color code and slowly decipher them? Only problem there is the resistors seem to have 5 stripes and i'm not sure how you tell which end to start at.
Sorry for the novice questions
main problems is the tiny resistors. Do I really have to look at each color code and slowly decipher them? Only problem there is the resistors seem to have 5 stripes and i'm not sure how you tell which end to start at.
Sorry for the novice questions
Hi guys, new to DIY. I ordered the kit from headn'hifi, I know how to solder and have all the right tools. BUT I can't work out how to sort and label all the parts I got and match them with the reference numbers on the BOM.
main problems is the tiny resistors. Do I really have to look at each color code and slowly decipher them? Only problem there is the resistors seem to have 5 stripes and i'm not sure how you tell which end to start at.
Sorry for the novice questions
main problems is the tiny resistors. Do I really have to look at each color code and slowly decipher them? Only problem there is the resistors seem to have 5 stripes and i'm not sure how you tell which end to start at.
Sorry for the novice questions
A question about bypass cap.
I finished building my 1st O2 successfully.During the build process a ques. popped into my mind ( Pls don't misunderstand me, I'm not doubting RS's design capability)-
In all audio system/sound cards employing opamps, I've seen a pair of small bypass cap. (typ. 0.1uF) located close to +V pin & gnd and -V pin & gnd of each opamp. Instead O2 has 0.22uF (6 of them- 2 for reg., 2 between +V/-V to gnd., 2 between +V & -V)but they are located far from both +/- pin of opamp(except C17,18 but still not in pairs for each JRC4556 ) & also not in pairs(1 for each rails). IMHO their should be 6 more bypass cap. in the existing design.I thought of adding bypass cap. underneath the PCB myself, but feared it might upset carefully designed ground plane layout by RS.
Any comments or thoughts are welcome
I finished building my 1st O2 successfully.During the build process a ques. popped into my mind ( Pls don't misunderstand me, I'm not doubting RS's design capability)-
In all audio system/sound cards employing opamps, I've seen a pair of small bypass cap. (typ. 0.1uF) located close to +V pin & gnd and -V pin & gnd of each opamp. Instead O2 has 0.22uF (6 of them- 2 for reg., 2 between +V/-V to gnd., 2 between +V & -V)but they are located far from both +/- pin of opamp(except C17,18 but still not in pairs for each JRC4556 ) & also not in pairs(1 for each rails). IMHO their should be 6 more bypass cap. in the existing design.I thought of adding bypass cap. underneath the PCB myself, but feared it might upset carefully designed ground plane layout by RS.
Any comments or thoughts are welcome
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Use/Buy a multimeter(even the El Cheapos will do) for measuring resistors & capacitors it will help a lot
Ok but what about the distance from +/- V pins of opamps & the cap. (C17,18 & U1)?.Though I admit the use/location of bypass cap. depends between the PCB designer's implementation & opamp datasheet recommendation. I think I've read this on tangentsoft "Use SMD cap. for bypass or use shortest lead for connecting to +/- pins of opamp & the remaining (longer) lead of the through hole cap. to gnd. to avoid lead inductance",
BTW I've not heard anybody's O2 going into HF oscillation though
How I wished RS was here to answer this Q.!
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tangentsoft is, IMHO, referring to the ideal. Surely in many many situations SMD is not a must, but in many many situations it would be the ideal implementation. Working in 3 dimensions on the circuit board necessitates some compromise. My recollection from RS's blog is that the circuit board layout was perhaps his greatest challenge with the O2.
My knowledge here is admittedly sketchy at best, unfortunately. I'm just a perpetual student of this stuff. My understanding of bypass theory though is that capacitance can be used to swamp inductance and vice versa. It's the negation of reactive parasitics that is one of the main goals in the selection of components and layout to achieve suitable bypassing.
My knowledge here is admittedly sketchy at best, unfortunately. I'm just a perpetual student of this stuff. My understanding of bypass theory though is that capacitance can be used to swamp inductance and vice versa. It's the negation of reactive parasitics that is one of the main goals in the selection of components and layout to achieve suitable bypassing.
With strict criteria like - using only thru holes comp.,AC/DC op, min. foot print, real world h/p drive capability backed by solid specs.... even RS admitted having difficulty in sharing real estate of PCB with 3-PCB mounting holes!
Still hats off to RS & special thanks to "jtktam" for providing PCBs & "swalter" for the critical components, without which I'd still be listening to CMOYs.
Still hats off to RS & special thanks to "jtktam" for providing PCBs & "swalter" for the critical components, without which I'd still be listening to CMOYs.
Yeah
, especially when using opamps with slew rate in excess of 2,000V/usec. designed for non-audio applications to drive headphones!
Everybody probably knows all of this already. But I'm happy that someone is even thinking about it at all. I do also think that it's a lot more important than many people believe.
There's bypassing and there's decoupling. People use those two words in different ways, often interchangeably. But in this post, by bypassing I mean using a capacitor to short-circuit high frequencies, which is needed because of the hidden positive feedback loop, through the power rail, that exists in many/most transistor amplifier topologies, at high frequencies.
For bypassing high frequencies, a capacitor that is more than two millimeters from an IC's power pins is probably too far away, in many cases, mainly because of the inductance of the conductors. You wouldn't hear the oscillations or ringing, because it would be at RF frequencies. But it could degrade the system's performance, possibly only subtly. It could also contribute to significanty hotter device temperatures.
For bypassing, the best practice is usually to use the capacitor with the smallest case size, since the capacitors don't usually have much intrinsic inductance, except for the equivalent of the self-inductance of a conductor with a length equal to the case length (or the lead spacing plus lead length, for a through-hole cap). So, usually, the largest capacitance value available in the smallest case size that will work is what would be used. Sometimes improvements can be had by mounting them in unusual ways, such as on their side (for surface mount).
Decoupling is when a capacitor is used as a local supply of current transients. Bypass capacitors will also provide as much decoupling as they can. But typically more capacitance is needed.
Decoupling caps could supply the transient current demands of more than one IC or active load. But their value and their distance from each load will determine at up to what amplitude and at up to and down to what frequencies they can be effective-enough.
It is relatively easy to calculate the worst case minimum capacitance required and the maximum distance or inductance that can be tolerated, given the load's current requirements and the acceptable maximum rail-voltage disturbance per unit of current for the worst-case shortest and longest time intervals.
But to get it right you usually do have to actually calculate them, because they can easily surprise you (although that's probably more common in decoupling for power amp output stages). It is also fairly common for there to be NO good-enough solution that can be physically implemented, especially when using DIY through-hole construction, without either using multiple smaller parallel caps, or, using real ground and power planes and many paralleled caps plus very-low-inductance connections to the planes.
But ALWAYS, it's a tradeoff, because you can always make the system's response more accurate if you spend more time or money or both on improving the decoupling capacitors' configuration.
There's bypassing and there's decoupling. People use those two words in different ways, often interchangeably. But in this post, by bypassing I mean using a capacitor to short-circuit high frequencies, which is needed because of the hidden positive feedback loop, through the power rail, that exists in many/most transistor amplifier topologies, at high frequencies.
For bypassing high frequencies, a capacitor that is more than two millimeters from an IC's power pins is probably too far away, in many cases, mainly because of the inductance of the conductors. You wouldn't hear the oscillations or ringing, because it would be at RF frequencies. But it could degrade the system's performance, possibly only subtly. It could also contribute to significanty hotter device temperatures.
For bypassing, the best practice is usually to use the capacitor with the smallest case size, since the capacitors don't usually have much intrinsic inductance, except for the equivalent of the self-inductance of a conductor with a length equal to the case length (or the lead spacing plus lead length, for a through-hole cap). So, usually, the largest capacitance value available in the smallest case size that will work is what would be used. Sometimes improvements can be had by mounting them in unusual ways, such as on their side (for surface mount).
Decoupling is when a capacitor is used as a local supply of current transients. Bypass capacitors will also provide as much decoupling as they can. But typically more capacitance is needed.
Decoupling caps could supply the transient current demands of more than one IC or active load. But their value and their distance from each load will determine at up to what amplitude and at up to and down to what frequencies they can be effective-enough.
It is relatively easy to calculate the worst case minimum capacitance required and the maximum distance or inductance that can be tolerated, given the load's current requirements and the acceptable maximum rail-voltage disturbance per unit of current for the worst-case shortest and longest time intervals.
But to get it right you usually do have to actually calculate them, because they can easily surprise you (although that's probably more common in decoupling for power amp output stages). It is also fairly common for there to be NO good-enough solution that can be physically implemented, especially when using DIY through-hole construction, without either using multiple smaller parallel caps, or, using real ground and power planes and many paralleled caps plus very-low-inductance connections to the planes.
But ALWAYS, it's a tradeoff, because you can always make the system's response more accurate if you spend more time or money or both on improving the decoupling capacitors' configuration.