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Re: How limitting do you think a scope would be if it were limitted to 35 volts?
Pesonally, I've always liked the idea of using a soundcard as a very basic, though limited scope. You don't always need a high end scope and using a soundcard saves some $$$. Plus just about every PC has a soundcard making it very convenient.
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This discussion did spark an idea for me last night. I have a Logitech USB headset. Then neat thing is that it's plug and play and requires no special drivers and is seen as just another audio device. It occured to me that one of these headsets could probably be easily "hacked" by cutting off the cable to the headset and installing a BNC on the little box for your Ch A in and a BNC or banana for your Ch A out, doubling as a very crude single channel scope and as an audio generator. ----- Original Message -----
From: lcdpublishing To: Electronics_101@... Sent: Sunday, October 08, 2006 9:50 AM Subject: [Electronics_101] Re: How limitting do you think a scope would be if it were limitted to 35 volts? Okay, I know you guys are probably wetting your pants laughing at me because I am so excited about a VERY CRUDE scope, but it is impressing me more and more. I wanted to check the actual ON time of a pulse generated by my AVR. In theory, it should be 50 uSec wide. I captured a single pulse and could point the cursor at the start and end of it and measure it's actual on time - 68 uSecs. This is measured at the output side of an opto isolator. I can clearly see the "Ringing" of the signal too. I don't have to turn the lights off to get a bright enough picture to see the trace! I was to the point with my HP scope of thinking you needed to have a Masters Degree in scope reading to get the most basic of measurements from it (along with a good dose of patience). I didn't realize till now how interesting and valuable they are! So, I guess Stefans point about the only thing worse than not having a scope is having a BAD scope is VERY TRUE. Sorry for my continued posts concerning my excitement. This experience working with this PC scope is proving to me that I am not as stupid as I thought I was :-) Chris |
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Re: Question around sound card curve tracer for William Kroyer
Yeah I figure with the soundcard o-scope software I could probably get some somewhat decent readings but really that's not my goal. I'm more or less just looking to use mine for reference. ie spotting bad/leaky caps, diodes, and transistors. The nice thing about doing it with a PC is that I could take screen captures of good signatures for various components and use them for comparison against a suspected bad one.
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----- Original Message -----
From: Gaurav Verma To: Electronics_101@... Sent: Sunday, October 08, 2006 7:01 AM Subject: Re: [Electronics_101] Question around sound card curve tracer for William Kroyer Hi I had made a circuit some time back for curve tracer, but it fed into a scope. The circuit was also verified by the group. The problem is that though I would get the look of the curve the values in the graph did not have ay number assigned to it. Thus it will be nice to have a curve tracer which would be computer controlled in its plot. Gaurav On 10/7/06, Roy J. Tellason <rtellason@...> wrote: > > On Saturday 07 October 2006 09:18 pm, Gaurav Verma wrote: > > Hi William > > > > In a previous post you discussed about a sound card based curve tracer. > I > > would request you to share information about the same. > > I am looking for the following information > > > > 1) Is it a circuit you made yourself or did you buy it > > 2) What is the software for it. > > > > I would request you to share the information around it with me. > > There was some discussion on curve tracers in here a while back. I forget > which kind were being talked about. There are basically two kinds... > > One is the sort that will display useful curves for characterizing a > semiconductor device. I have one of those, a B&K, though it has some > limitations like only dealing with depletion-mode FETs and only going to > 100V > maximum. > > The other kind is more general, for getting an idea of what the > characteristics are of many different kinds of components, and I know > there > are some circuits of that sort out there on the 'net as well. > > Which are you looking to do? > > -- > Member of the toughest, meanest, deadliest, most unrelenting -- and > ablest -- form of life in this section of space, a critter that can > be killed but can't be tamed. --Robert A. Heinlein, "The Puppet Masters" > - > Information is more dangerous than cannon to a society ruled by lies. > --James > M Dakin > > > |
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Re: Scope Probes - what is in them?
Stefan Trethan
On Sun, 08 Oct 2006 16:02:46 +0200, Shawn Upton <kb1ckt@...> wrote:
The characteristic impedance does not change (much) with frequency, not at all with ideal coax. ;-) If you have an infinitely long piece of coax and connect your ohmmeter you will read 50ohms (or whatever it's impedance is). It looks capacitive if you don't terminate it, which is what Chris is going to do. But that change in what it appears like is because of lack of termination, not the frequency. ST |
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Re: Scope Probes - what is in them?
Shawn Upton
I concur. "Real" probes use lossy coax so as to
reduce reflections; and the 10: divider at the probe tip has a resistor from center conductor to braid, and a resistor in parallel to an adjustable capacitor from the center conductor to the actual tip (that goes to the signal under test). The adjustable capacitor is used to adjust the probe so that signal edges do not have excessive overshoot or undershoot. But below 100kHz, I know regular coax looks more capacitive than anything else (and not 50 ohms). Tightly twisted wire, or even twisted pair with a shield, should work well enough for feeding a sound card. As for including compensation, I don't know: you sorta need a good square source to test against. You could perhaps use one of your Atmel outputs *with nothing attached to that pin* with a 1kHz or 10kHz square wave (doesn't have to be perfect) to see if the edges are clean or not. Odds are, you don't need compensation; but it can't hurt to check. Shawn --- Stefan Trethan <stefan_trethan@...> wrote: Most likely you have either 1:1 probes, which are aShawn Upton, KB1CKT __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around |
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Re: Scope Probes - what is in them?
LOL! You got that right! It might look neat, but it is pretty darn
expensive :-( Chris --- In Electronics_101@..., "Stefan Trethan" <stefan_trethan@...> wrote: the hasshort term, just about everything I am going to check with this inside computers. |
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Re: How limitting do you think a scope would be if it were limitted to 35 volts?
Okay, I know you guys are probably wetting your pants laughing at
me because I am so excited about a VERY CRUDE scope, but it is impressing me more and more. I wanted to check the actual ON time of a pulse generated by my AVR. In theory, it should be 50 uSec wide. I captured a single pulse and could point the cursor at the start and end of it and measure it's actual on time - 68 uSecs. This is measured at the output side of an opto isolator. I can clearly see the "Ringing" of the signal too. I don't have to turn the lights off to get a bright enough picture to see the trace! I was to the point with my HP scope of thinking you needed to have a Masters Degree in scope reading to get the most basic of measurements from it (along with a good dose of patience). I didn't realize till now how interesting and valuable they are! So, I guess Stefans point about the only thing worse than not having a scope is having a BAD scope is VERY TRUE. Sorry for my continued posts concerning my excitement. This experience working with this PC scope is proving to me that I am not as stupid as I thought I was :-) Chris |
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Re: Scope Probes - what is in them?
Stefan Trethan
On Sun, 08 Oct 2006 15:32:11 +0200, lcdpublishing <lcdpublishing@...> wrote:
Gotcha, Well, it's not like you are unaware of the effects mains voltage has inside computers. ST |
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OT: Going offline for a few days....
D P
Hi all,
We are having problems with our ISP while setting up a wireless network, so I am terribly sorry if you get delayed mail, etc. I will post once in a while because i would be using someone else's computer to post messages etc. Sorry! Regards David _________________________________________________________________ Windows Live? Messenger has arrived. Click here to download it for free! |
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Re: Scope Probes - what is in them?
Gotcha,
My probes have the switch for 1:1 and 10:1. So, I could use the little circuit board I made up and just add a BNC connector to it along with an enclosure box and I should be in good shape. For the short term, just about everything I am going to check with this thing is going to be 5 volts, but being the fumble fingers I am lately, I have to be extrememly careful not to touch something of higher voltage. Thanks! Chris --- In Electronics_101@..., "Stefan Trethan" <stefan_trethan@...> wrote: through cable, or 10:1 probes, which have a frequency compensated dividerinside. With the probably low input impedance of the soundcard the 10:1are no good. Use 1:1 and make your own divider if you need more voltage,with resistors, compensation doesn't matter at the low frequency. |
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Re: Scope Probes - what is in them?
Stefan Trethan
Most likely you have either 1:1 probes, which are a straight through cable, or 10:1 probes, which have a frequency compensated divider inside. With the probably low input impedance of the soundcard the 10:1 are no good. Use 1:1 and make your own divider if you need more voltage, with resistors, compensation doesn't matter at the low frequency.
ST |
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Scope Probes - what is in them?
Strange question - I know :-(
Let me explain. I will have to tinker with this soundcard "Scope" for a while till I can afford something better. Right now I am using a couple of wires - 8 diodes - 2 resistors and some wires as a probe. This was built based on the schematic in the information for the Virtins Scope. I have a couple scope probes and suspect those are more than just a clip on one end and a connector on the other. The Virtins website sells a probe for $29.00 and it appears the only difference is the connector RCA instead of the BNC connector. I am wondering if I can't modify my current probe to work, or even to make an adapter between the small connector on the computers sound card and the BNC connector. It appears as though, using the line input for the sound card, you have a two volt limit. So, not knowing what is inside a probe and knowing that my probes are basically new, I don't want to start hacking without knowledge :- ) Chris |
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Re: How limitting do you think a scope would be if it were limitted to 35 volts?
Steve, it appears to be freeware as it doesn't seem to have any
indications of registration etc. I dunno to be honest - it was free to download - it didn't require registration - and I do beleive is has limitted features. --- In Electronics_101@..., "Steve" <alienrelics@...> wrote: from isVirtins. that it works full screen |
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Re: Question around sound card curve tracer for William Kroyer
Gaurav Verma
Hi
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I had made a circuit some time back for curve tracer, but it fed into a scope. The circuit was also verified by the group. The problem is that though I would get the look of the curve the values in the graph did not have ay number assigned to it. Thus it will be nice to have a curve tracer which would be computer controlled in its plot. Gaurav On 10/7/06, Roy J. Tellason <rtellason@...> wrote:
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Re: Gain Vs. Frequency meter - Where would I start?
Leon Heller
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----- Original Message -----
From: "sstandfast" <sstandfast@...> To: <Electronics_101@...> Sent: Sunday, October 08, 2006 7:27 AM Subject: [Electronics_101] Gain Vs. Frequency meter - Where would I start? Hey guys,More like a spectrum analyser. Lots of audio spectrum analyser programs are available that use the PC sound card, they just do an FFT on the input signal. An application for a dsPIC evaluation board does an FFT and displays the spectrum on an LCD, an ordinary PIC won't have enough processing power. Leon |
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Gain Vs. Frequency meter - Where would I start?
Hey guys,
I've been reading the latest posts about various scopes and the pro's and con's of each and that got me thinking about a (hopefully) small project of a gain vs. frequency meter. The device would take an input signal and display the relative db of each frequency present in the signal. Similar to the Forier Analysis in PSpice. The reference voltage should be variable and it doesn't have to have an exremely wide bandwidth - audio range would be enough. A graphic LCD could then be used to display the output. My question is, what would be needed for a device like this. I know that an input buffer/isolation stage (unity-gain OP-AMP's) to provide a high-impedance input will be needed, and the magnitude comparison can be achieved with either a compariator or an op-amp. I can program a PIC to display the output, but what would be needed in the middle? How would I seperate out each frequency? Also, would this device be considered a "Frequency Counter"? Thanks for any tips, Shawn |
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Re: Question around sound card curve tracer for William Kroyer
Roy J. Tellason
On Saturday 07 October 2006 09:18 pm, Gaurav Verma wrote:
Hi WilliamThere was some discussion on curve tracers in here a while back. I forget which kind were being talked about. There are basically two kinds... One is the sort that will display useful curves for characterizing a semiconductor device. I have one of those, a B&K, though it has some limitations like only dealing with depletion-mode FETs and only going to 100V maximum. The other kind is more general, for getting an idea of what the characteristics are of many different kinds of components, and I know there are some circuits of that sort out there on the 'net as well. Which are you looking to do? -- Member of the toughest, meanest, deadliest, most unrelenting -- and ablest -- form of life in this section of space, a critter that can be killed but can't be tamed. --Robert A. Heinlein, "The Puppet Masters" - Information is more dangerous than cannon to a society ruled by lies. --James M Dakin |
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Re: How limitting do you think a scope would be if it were limitted to 35 volts?
Roy J. Tellason
On Saturday 07 October 2006 05:17 pm, lcdpublishing wrote:
Hmmm, that sounds neat. I will have to look through my box ofNot the caps, though. I had one die on me here a while back, and there really wasn't all that much to it -- the chip itself and maybe a couple of buffers and such, and the rest of what was on that card was caps and some connectors for things like cd audio and such. It shouldn't be too hard to see which caps you need to mess with, just look from the line in connector (that is the one you're using right?) and trace it out. You probably don't even need to remove them, just check first to see if there's any DC present on the side away from the jack, and if not, solder a bit of wire across them and you should be good to go. Of course this puts the input jack connecting directly to the chip, but I expect your use probably has some external circuitry anyhow, doesn't it? The little bit of stuff I recall looking at for pc scopes did. And in fact it may have been on one of those pages where I saw this idea in the first place, I don't recall. --- In Electronics_101@..., "Roy J. Tellason"-- Member of the toughest, meanest, deadliest, most unrelenting -- and ablest -- form of life in this section of space, a critter that can be killed but can't be tamed. --Robert A. Heinlein, "The Puppet Masters" - Information is more dangerous than cannon to a society ruled by lies. --James M Dakin |
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Re: How limitting do you think a scope would be if it were limitted to 35 volts?
Is the old version freeware now, or still shareware?
Has anyone tried modifying a sound card to take DC input? Steve Greenfield PS please don't forget to trim --- In Electronics_101@..., "lcdpublishing" <lcdpublishing@...> wrote:
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Steven AE7HD
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