|
|
Post by kcatthedog on Feb 2, 2018 6:43:42 GMT -6
Have always loved the name but never used one.
In the context of DIY audio and trouble shooting gear, what does one do with an oscilloscope ?
What features are important to have ?
Thx!
|
|
|
|
Post by matt@IAA on Feb 2, 2018 9:06:39 GMT -6
:-p
|
|
|
|
Post by johneppstein on Feb 2, 2018 14:50:36 GMT -6
Have always loved the name but never used one. In the context of DIY audio and trouble shooting gear, what does one do with an oscilloscope ? What features are important to have ? Thx! What does one do? Many, many things. The simplest description is that it gives you a visual representation of an electrical signal. What use is this? There are many uses. Most scopes come with a graticule, like the lines on graph paper, imposed on the screen. This gives you a measurement of volts in the vertical dimension and time (frequency) in the horizontal. Since you're getting a direct visual depiction of the signal you can see your waveform, which can, with proper training, give you some idea of what sort of distortion you might have. By using the triggered sweep function and an audio sweep generator you can see what your frequency response is like. By feeding different signals into the vertical and horizontal inputs you can generate Lissajous figures, which can tell you all manner of things regarding stuff like stereo balance, head alignment on tape decks, and a whole lot of other things. With a curve tracer attachment you can analyze, compare, and match transistors. But what is probably the most common and important use is signal tracing malfunctioning gear. You can look for where noise comes from, hunt down stray oscillations, and determine where in circuit it ceases to pass audio. For most audio work you don't really need much in the way of frequency response - 10MHz will do an adequate job Most service scopes will give you 40 or 50 MHz. For modern digital work you'd need much higher response, but you're not likely to need that. You'll want dual channels so you can compare input signal to signals at various points along the circuit path. For tube work you'll want something that can deal with high input voltages. NOTE - not all inexpensive digital scope kits can do this. You'll want accessable input for horizontal signal as well as vertical if you want to see frequency response sweeps. There are three basic types of (analog) dual trace scopes - those that have two completely separate sweeps circuits, those that alterrnate sweeps between channel A and B, and those that chop the sweep between channels on each sweep. Obviously, the first type is the best, although any of them will work for most basic audio work. Some give you a choice of modes - the frequency response will vary depending on mode. So will quality of image. The most sophisticated analog scopes and many digital scopes give you some degree of storage for waveforms. This isn't all that useful for basic troubleshooting and measurement, but could be very handy for product/mod development and scientific stuff. |
|
|
|
Post by johneppstein on Feb 3, 2018 14:58:44 GMT -6
|
|
ericn
Temp
Balance Engineer
Posts: 16,107 
|
Post by ericn on Feb 5, 2018 15:50:50 GMT -6
Have always loved the name but never used one. In the context of DIY audio and trouble shooting gear, what does one do with an oscilloscope ? What features are important to have ? Thx! What does one do? Many, many things. The simplest description is that it gives you a visual representation of an electrical signal. What use is this? There are many uses. Most scopes come with a graticule, like the lines on graph paper, imposed on the screen. This gives you a measurement of volts in the vertical dimension and time (frequency) in the horizontal. Since you're getting a direct visual depiction of the signal you can see your waveform, which can, with proper training, give you some idea of what sort of distortion you might have. By using the triggered sweep function and an audio sweep generator you can see what your frequency response is like. By feeding different signals into the vertical and horizontal inputs you can generate Lissajous figures, which can tell you all manner of things regarding stuff like stereo balance, head alignment on tape decks, and a whole lot of other things. With a curve tracer attachment you can analyze, compare, and match transistors. But what is probably the most common and important use is signal tracing malfunctioning gear. You can look for where noise comes from, hunt down stray oscillations, and determine where in circuit it ceases to pass audio. For most audio work you don't really need much in the way of frequency response - 10MHz will do an adequate job Most service scopes will give you 40 or 50 MHz. For modern digital work you'd need much higher response, but you're not likely to need that. You'll want dual channels so you can compare input signal to signals at various points along the circuit path. For tube work you'll want something that can deal with high input voltages. NOTE - not all inexpensive digital scope kits can do this. You'll want accessable input for horizontal signal as well as vertical if you want to see frequency response sweeps. There are three basic types of (analog) dual trace scopes - those that have two completely separate sweeps circuits, those that alterrnate sweeps between channel A and B, and those that chop the sweep between channels on each sweep. Obviously, the first type is the best, although any of them will work for most basic audio work. Some give you a choice of modes - the frequency response will vary depending on mode. So will quality of image. The most sophisticated analog scopes and many digital scopes give you some degree of storage for waveforms. This isn't all that useful for basic troubleshooting and measurement, but could be very handy for product/mod development and scientific stuff. Don't forget many scopes have a built in signal generator ! |
|
|
|
Post by johneppstein on Feb 5, 2018 17:49:23 GMT -6
What does one do? Many, many things. The simplest description is that it gives you a visual representation of an electrical signal. What use is this? There are many uses. Most scopes come with a graticule, like the lines on graph paper, imposed on the screen. This gives you a measurement of volts in the vertical dimension and time (frequency) in the horizontal. Since you're getting a direct visual depiction of the signal you can see your waveform, which can, with proper training, give you some idea of what sort of distortion you might have. By using the triggered sweep function and an audio sweep generator you can see what your frequency response is like. By feeding different signals into the vertical and horizontal inputs you can generate Lissajous figures, which can tell you all manner of things regarding stuff like stereo balance, head alignment on tape decks, and a whole lot of other things. With a curve tracer attachment you can analyze, compare, and match transistors. But what is probably the most common and important use is signal tracing malfunctioning gear. You can look for where noise comes from, hunt down stray oscillations, and determine where in circuit it ceases to pass audio. For most audio work you don't really need much in the way of frequency response - 10MHz will do an adequate job Most service scopes will give you 40 or 50 MHz. For modern digital work you'd need much higher response, but you're not likely to need that. You'll want dual channels so you can compare input signal to signals at various points along the circuit path. For tube work you'll want something that can deal with high input voltages. NOTE - not all inexpensive digital scope kits can do this. You'll want accessable input for horizontal signal as well as vertical if you want to see frequency response sweeps. There are three basic types of (analog) dual trace scopes - those that have two completely separate sweeps circuits, those that alterrnate sweeps between channel A and B, and those that chop the sweep between channels on each sweep. Obviously, the first type is the best, although any of them will work for most basic audio work. Some give you a choice of modes - the frequency response will vary depending on mode. So will quality of image. The most sophisticated analog scopes and many digital scopes give you some degree of storage for waveforms. This isn't all that useful for basic troubleshooting and measurement, but could be very handy for product/mod development and scientific stuff. Don't forget many scopes have a built in signal generator ! I'm not sure if I'd say "many" - the only one I remember using that did was a Tektronix that had a docking bay for various additional modules, although I wouldn't call it part of the scope proper. And I'd probably want my signal generator(s) kept separate, anyway - unless they came with the scope. I have a nice old tube HP sine wave generator (and the matching VTVM) that I really need to give a good cleaning and a little Chinese switchable frequency handheld function generator that's nice for its portability. I need a good benchtop function generator and a sweep generator... |
|
ericn
Temp
Balance Engineer
Posts: 16,107
|
Post by ericn on Feb 5, 2018 18:28:35 GMT -6
Don't forget many scopes have a built in signal generator ! I'm not sure if I'd say "many" - the only one I remember using that did was a Tektronix that had a docking bay for various additional modules, although I wouldn't call it part of the scope proper. And I'd probably want my signal generator(s) kept separate, anyway - unless they came with the scope. I have a nice old tube HP sine wave generator (and the matching VTVM) that I really need to give a good cleaning and a little Chinese switchable frequency handheld function generator that's nice for its portability. I need a good benchtop function generator and a sweep generator... John About a year ago when I bought my LG Digital OEM scope with signal generator for the princely sum of $60 I noticed a fair number of more modern scopes in the affordable range have built in signal generators. This is a great feature if your going to be using the scope in more than one location because it means one less thing to carry ! I know on the old HP, Tektronix and Leaders it was an expensive option on their modular systems, but on the newer lesser known digital units of which you can find a ton of used at affordable prices, had a ITT acedemy or what ever they called sticker on the back! |
|
|
|
Post by johneppstein on Feb 5, 2018 20:57:18 GMT -6
I'm not sure if I'd say "many" - the only one I remember using that did was a Tektronix that had a docking bay for various additional modules, although I wouldn't call it part of the scope proper. And I'd probably want my signal generator(s) kept separate, anyway - unless they came with the scope. I have a nice old tube HP sine wave generator (and the matching VTVM) that I really need to give a good cleaning and a little Chinese switchable frequency handheld function generator that's nice for its portability. I need a good benchtop function generator and a sweep generator... John About a year ago when I bought my LG Digital OEM scope with signal generator for the princely sum of $60 I noticed a fair number of more modern scopes in the affordable range have built in signal generators. This is a great feature if your going to be using the scope in more than one location because it means one less thing to carry ! I know on the old HP, Tektronix and Leaders it was an expensive option on their modular systems, but on the newer lesser known digital units of which you can find a ton of used at affordable prices, had a ITT acedemy or what ever they called sticker on the back! Really? How interesting! Where did you see them? Because I'm not. (I'm not calling you out, I'm just not seeing them from any of the test gear dealers I've checked online.) How good are these generators? For that matter, how good are the scopes - specifically for audio, which often involves high voltage tube based gear? If a scope can't accept at least 1000V at its inputs it's useless for tube work. I must admit that I've been leery of all the low priced digital scopes that have hit the market in recent years, for a number of reasons, so I may very well have missed something - and the digital scopes from manufacturers I know and trust aren't exactly cheap and often seem to concentrate on features that don't seem to me to be very important or even relevant for basic audio service. My assumption has been that since there are very few real electronic service shops anymore the focus has shifted to scopes designed for development, and very little development these days involves high voltage (tube) devices outside of a few highly specialized areas, such as broadcast transmitters, military and avionic radar, etc. I mean, how many basic audio techs need a storage scope with 64 memories and 8 traces? What kind of screen resolution do you get with that many traces on a 6x4 LED rectangle, anyway? (I like the resolution of CRTs.) As far as portability issues are concerned, my little Chinese function generator is almost exactly the size of my medium sized cell phone. Not much to lug around, really. And it cost me around $35 new. Actually, I don't think I'd want my primary signal generator built into my scope - that sounds like a recipe for long festoons of cable when. for example, injecting a signal into the input of a chain on one side of the room and looking at the output of a recorder on the other. |
|
ericn
Temp
Balance Engineer
Posts: 16,107
|
Post by ericn on Feb 5, 2018 21:32:06 GMT -6
John About a year ago when I bought my LG Digital OEM scope with signal generator for the princely sum of $60 I noticed a fair number of more modern scopes in the affordable range have built in signal generators. This is a great feature if your going to be using the scope in more than one location because it means one less thing to carry ! I know on the old HP, Tektronix and Leaders it was an expensive option on their modular systems, but on the newer lesser known digital units of which you can find a ton of used at affordable prices, had a ITT acedemy or what ever they called sticker on the back! Really? How interesting! How good are these generators? For that matter, how good are the scopes - specifically for audio, which often involves high voltage tube based gear? If a scope can't accept at least 1000V at its inputs it's useless for tube work. I must admit that I've been leery of all the low priced digital scopes that have hit the market in recent years, for a number of reasons, so I may very well have missed something - and the digital scopes from manufacturers I know and trust aren't exactly cheap and often seem to concentrate on features that don't seem to me to be very important or even relevant for basic audio service. My assumption has been that since there are very few real electronic service shops anymore the focus has shifted to scopes designed for development, and very little development these days involves high voltage (tube) devices outside of a few highly specialized areas, such as broadcast transmitters, military and avionic radar, etc. I mean, how many basic audio techs need a storage scope with 64 memories and 8 traces? What kind of screen resolution do you get with that many traces on a 6x4 LED rectangle, anyway? And how much resolution is lost on a pixelated digital screen? As far as portability issues are concerned, my little Chinese function generator is almost exactly the size of my medium sized cell phone. Not much to lug around, really. And it cost me around $35 new. I don't know, many of the bench top's I have seen are rated high enough but we both know, that means sure if the moon is in the right phase, the temperature is right and you know the secret handshake, maybe! I bought mine for some 500 series assembly, working on the Ampex and well it was there! I do know a couple of IT hate the stupid portable LCD crap no matter the price! |
|
|
|
Post by gar381 on Feb 5, 2018 23:05:38 GMT -6
Get a working Tektronix 465 or 465B on ebone for $100-$200.
Great for anything Audio and will probably last you for
the rest of your life.
Gary
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Feb 6, 2018 9:44:43 GMT -6
If you're at the point of writing some software to run on your hardware, a digital storage scope is invaluable. There's usually a GPIO port or two available and you can use those to trigger the scope. You could easily measure whether or not something was happening or how long it took. I really did like the little Tektronix scope I had at Lexicon. I have absolutely no need for one now, but I'd still like to have it ;-)
|
|
|
|
Post by indiehouse on Feb 6, 2018 15:18:45 GMT -6
Get a working Tektronix 465 or 465B on ebone for $100-$200. Great for anything Audio and will probably last you for the rest of your life. Gary What do you think of a BK Precision 2120b? I picked it up on ebay last year for 75 bucks in order to calibrate some compressors, but I haven't learned how to use it yet. |
|
|
|
Post by svart on Feb 6, 2018 15:46:46 GMT -6
|
|
|
|
Post by svart on Feb 6, 2018 15:49:14 GMT -6
|
|
|
|
Post by johneppstein on Feb 6, 2018 20:36:48 GMT -6
Get a working Tektronix 465 or 465B on ebone for $100-$200. Great for anything Audio and will probably last you for the rest of your life. Gary What do you think of a BK Precision 2120b? I picked it up on ebay last year for 75 bucks in order to calibrate some compressors, but I haven't learned how to use it yet. It's a great service tech's scope. I'm pretty sure I used to have one or a very similar model. B&K is a well respected test gear company. EDIT: After looking on Ebay I think mine was a 2160, similar but a bit wider response. I saw one for $100 that's I'm seriously considering for myself, as it would be cheaper than repairing the damage my Leader suffered to some of its controls during my move last year. When buying a used scope for calibration purposes make sure that the scope itself is in calibration.... |
|
|
|
Post by johneppstein on Feb 6, 2018 20:54:30 GMT -6
Really? I don't think so. Basic signal tracing, maybe. On solid state gear only. For one thing the screen is too small to show much detail. How are you going to view parasitic oscillations on a screen that tiny? For another it can only take 50 volts peak input signal with a 1x probe. Which means you'd need a 20x probe to do tube amp work safely. And looking at Ebay I don't see any 20x probes. 200MHz, yes. x20 volt, no. which means you try to use it on tube gear and it emits the magic smoke shortly before fusing into a lump of molten plastic. And only single trace. I've been looking at handhelds for years decades but the only ones I've seen that I'd really want are expensive. And even those still have a screen resolution problem as I see it. The Flukes are really cute, but.... So are the Tektronix. |
|
|
|
Post by svart on Feb 7, 2018 14:24:33 GMT -6
Really? I don't think so. Basic signal tracing, maybe. On solid state gear only. For one thing the screen is too small to show much detail. How are you going to view parasitic oscillations on a screen that tiny? For another it can only take 50 volts peak input signal with a 1x probe. Which means you'd need a 20x probe to do tube amp work safely. And looking at Ebay I don't see any 20x probes. 200MHz, yes. x20 volt, no. which means you try to use it on tube gear and it emits the magic smoke shortly before fusing into a lump of molten plastic. And only single trace. I've been looking at handhelds for years decades but the only ones I've seen that I'd really want are expensive. And even those still have a screen resolution problem as I see it. The Flukes are really cute, but.... So are the Tektronix. I did say "general".. I don't consider tubes and HV to be general in any sense of the word. I can see small screens just fine. Get yourself some old man reading glasses if you can't. Besides, there are no 20x probes, only 1x, 10x, 100x.. Plenty of 100x probes on ebay for high voltage work. |
|
|
|
Post by johneppstein on Feb 7, 2018 18:03:15 GMT -6
Really? I don't think so. Basic signal tracing, maybe. On solid state gear only. For one thing the screen is too small to show much detail. How are you going to view parasitic oscillations on a screen that tiny? For another it can only take 50 volts peak input signal with a 1x probe. Which means you'd need a 20x probe to do tube amp work safely. And looking at Ebay I don't see any 20x probes. 200MHz, yes. x20 volt, no. which means you try to use it on tube gear and it emits the magic smoke shortly before fusing into a lump of molten plastic. And only single trace. I've been looking at handhelds for years decades but the only ones I've seen that I'd really want are expensive. And even those still have a screen resolution problem as I see it. The Flukes are really cute, but.... So are the Tektronix. I did say "general".. I don't consider tubes and HV to be general in any sense of the word. I can see small screens just fine. Get yourself some old man reading glasses if you can't. Besides, there are no 20x probes, only 1x, 10x, 100x.. Plenty of 100x probes on ebay for high voltage work. I consider tubes to be VERY general in the audio field. They're all over the place. Tube compressors, tube preamps, tube power amps, tube guitar amps..... But then I started with tubes....... I have old man reading glasses. I use them constantly. I just don't see how a pixillated screen that small could show fine detail very well. Whereas even an entry level Heathkit analog scope can. |
|
|
|
Post by kcatthedog on Feb 8, 2018 7:36:00 GMT -6
|
|
|
|
Post by johneppstein on Feb 8, 2018 12:30:35 GMT -6
<chuckle> I'm a bit surprised to see how well some of those have held their value. I used to pick up the old grey single trace ones for about $20 at the flea market, back in the day... |
|
|
|
Post by kcatthedog on Feb 8, 2018 12:44:09 GMT -6
^^this^^ stated without a trace of sarcasm !  |
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Feb 22, 2018 23:58:11 GMT -6
Those smallish mini scopes like the one svart showed or the DSO138 are actually great e.g. to carry around in your guitar case when you are on your way to live gigs. Yes, just to be able to trace audio signals, i mean, i do not carry a scope around all the time, but these little things are awesome to have in your shoulder or notebook bag etc. ...
And i think they are pretty usable in many applications, just not as "the" scope in the workshop...
|
|
ericn
Temp
Balance Engineer
Posts: 16,107
|
Post by ericn on Feb 23, 2018 9:08:29 GMT -6
<chuckle> I'm a bit surprised to see how well some of those have held their value. I used to pick up the old grey single trace ones for about $20 at the flea market, back in the day... The only thing is with Heathkit is its often only as good as the idiot who built it ! That should be Jeff’s New Moto at CAPI! |
|
