Should I buy a cheap oscilloscope?
- modman
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There are so many of them on Ebay for <100EUR...
What resolution should it have to be useful? Channels? If I understand it correctly, I could tune and debug circuits without having to turn on an amp and wake up the kids at night?
Or better try a free software based oscilloscope?
Or do I need a very good understanding of electronics to be able to use it properly?
thanks!
What resolution should it have to be useful? Channels? If I understand it correctly, I could tune and debug circuits without having to turn on an amp and wake up the kids at night?
Or better try a free software based oscilloscope?
Or do I need a very good understanding of electronics to be able to use it properly?
thanks!
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- analogguru
- Old Solderhand
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20 Mhz should be enough to see even HF-oscillation (even 5 Mhz to 10 Mhz will do it for audio applications)modman wrote:There are so many of them on Ebay for <100EUR...
What resolution should it have to be useful?
one is enough, two are better.modman wrote: Channels?
If you don´t tune and debug an amp you don´t need to turn it on. If you tune and debug an amp you have to use an load resistor. A cheap 8 Ohm/50W load resistor can be made with 6 pcs. 47 Ohm/9Watt resistors in parallel (for 8 Ohm/100W use 12 pcs. 100 Ohm in parallel). If you make two of them you can connect them in series for 16 Ohm or in parallel to achieve 4 Ohm.modman wrote: If I understand it correctly, I could tune and debug circuits without having to turn on an amp and wake up the kids at night?
The resolution of soundcard based are not satisfying me.modman wrote: Or better try a free software based oscilloscope?
If you find an acceptable one, please let me know.
The oscilloscope ? Not really....modman wrote: Or do I need a very good understanding of electronics to be able to use it properly?
thanks!
The software ? maybe.... depends on the programmer
analogguru
There´s a sucker born every minute - and too many of them end up in the bootweak pedal biz.
- marshmellow
- Cap Cooler
The problem with software based oscilloscopes is the voltage input level. If you work on a tube amp you might heavily overload (destroy?) your line input on the soundcard. Of course you could work with a voltage divider in front but it isn't the nicest solution to me.
If it's only for effects building there should be no problems with the soundcard osci.
I would look for an older Hameg one (at least I like working with those) with the specifications Analogguru posted. They are on Ebay all the time and well within that price range.
If it's only for effects building there should be no problems with the soundcard osci.
I would look for an older Hameg one (at least I like working with those) with the specifications Analogguru posted. They are on Ebay all the time and well within that price range.
- modman
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Thanks for specs.
I wasn't really thinking about "using on oscilloscope to test an amp" but rather "turning on an amp to connect a effect circuit to it in order to debug it with the audio probe."
Isn't this the only way to know what a circuit is really doing?
Would it help me repair complexer circuits like Digital Delays and an EH microsynth?
My Screamer works perfectly but sounds terrible - a scope would help me to pinpoint what that otherwise undescribeable "bad sound" is and where it comes from. Right?
It seems I should be able to find one under 50 EUR even.
I wasn't really thinking about "using on oscilloscope to test an amp" but rather "turning on an amp to connect a effect circuit to it in order to debug it with the audio probe."
Isn't this the only way to know what a circuit is really doing?
Would it help me repair complexer circuits like Digital Delays and an EH microsynth?
My Screamer works perfectly but sounds terrible - a scope would help me to pinpoint what that otherwise undescribeable "bad sound" is and where it comes from. Right?
It seems I should be able to find one under 50 EUR even.
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- analogguru
- Old Solderhand
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yes.....BTW, do you have a microsynth ?Would it help me repair complexer circuits like Digital Delays and an EH microsynth?
What are you waiting for ?It seems I should be able to find one under 50 EUR even.
analogguru
There´s a sucker born every minute - and too many of them end up in the bootweak pedal biz.
- modman
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Yes. It's not mine, but belongs to a friend. It had volume issues and was not true bypass and a real tone sucker. Just wanted to install a true bypass, but there is nothing coming from the circuit anymore. Audio probing that is not so much fun, so it's something I've been postponing a long time now. I gave him my Prunes and Custard clone to keep him happy.analogguru wrote:yes.....BTW, do you have a microsynth ?Would it help me repair complexer circuits like Digital Delays and an EH microsynth?
Some slider potis have broken off, which in itself is not a problem, but testifies of the hardship the box has been through. Maybe the potis have internal damage too. Was reluctant to take it completely apart, but there is no choice now.
Do you want detailed pcb pictures?
Just some good luck and a local auction to avoid a large shipping feeIt seems I should be able to find one under 50 EUR even.
What are you waiting for ?
analogguru
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- analogguru
- Old Solderhand
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Here is something to read in the meantime:
http://www.pmillett.com/Books/smith_oscilloscope.pdf
http://www.pmillett.com/Books/intro_haas_oscope.pdf
analogguru
http://www.pmillett.com/Books/smith_oscilloscope.pdf
http://www.pmillett.com/Books/intro_haas_oscope.pdf
analogguru
There´s a sucker born every minute - and too many of them end up in the bootweak pedal biz.
- modman
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Thanks AG! Just what I needed.
Checked some auctions and tis really true the 100 EUR budget that would get me at least a 20Mhz dual channel on ebay, wouldn't even buy me a new 1 channel 10Mhz step in model at Conrad:
2 channel 20Mhz
http://www.conrad.be/goto.php?artikel=120632
OSCILLOSCOPE-HAMEG-203-4 2 channel 20Mhz at 57 EUR
Tektronix-465-Oscilloscope-Dual-Trace-100-MHz sold at 97 EUR
Oszilloskope-TEKTRONIX-453-Dual-Channel-50-MHz sold at 86 EUR
Checked some auctions and tis really true the 100 EUR budget that would get me at least a 20Mhz dual channel on ebay, wouldn't even buy me a new 1 channel 10Mhz step in model at Conrad:
2 channel 20Mhz
http://www.conrad.be/goto.php?artikel=120632
OSCILLOSCOPE-HAMEG-203-4 2 channel 20Mhz at 57 EUR
Tektronix-465-Oscilloscope-Dual-Trace-100-MHz sold at 97 EUR
Oszilloskope-TEKTRONIX-453-Dual-Channel-50-MHz sold at 86 EUR
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- RLBJR65
- Resistor Ronker
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I've been meaning to scan these More reading material!
http://sites.google.com/site/diyjunkie/ ... edirects=0
http://sites.google.com/site/diyjunkie/ ... edirects=0
http://sites.google.com/site/diyjunkie/ ... edirects=0
http://sites.google.com/site/diyjunkie/ ... edirects=0
I've got an old Fairchild / Du Mont 304A. It's a tank, all tube made in the late 50's. Sadley it no longer works.
One of these days I'll pull all the tubes and test them. It also has a couple of pots that need replaced. I suppose all the electrolytic caps should be changed as well.
I got it free but I'm not sure it's really worth rebuilding.
http://sites.google.com/site/diyjunkie/ ... edirects=0
http://sites.google.com/site/diyjunkie/ ... edirects=0
http://sites.google.com/site/diyjunkie/ ... edirects=0
http://sites.google.com/site/diyjunkie/ ... edirects=0
I've got an old Fairchild / Du Mont 304A. It's a tank, all tube made in the late 50's. Sadley it no longer works.
One of these days I'll pull all the tubes and test them. It also has a couple of pots that need replaced. I suppose all the electrolytic caps should be changed as well.
I got it free but I'm not sure it's really worth rebuilding.
- analogguru
- Old Solderhand
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Does it already have trigger ?I've got an old Fairchild / Du Mont 304A.
I have an old Heathkit tube oszilloskop which doesn´t have trigger, only sync.
analogguru
There´s a sucker born every minute - and too many of them end up in the bootweak pedal biz.
- RLBJR65
- Resistor Ronker
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Don't know... I think only sync.analogguru wrote:Does it already have trigger ?I've got an old Fairchild / Du Mont 304A.
analogguru
I know next to nothing about scopes the only times I have used one were with sombody who actualy knew what they were doing.
Here is a pic of mine http://sites.google.com/site/diyjunkie/ ... edirects=0
and here is a Q&D scan of the manual http://sites.google.com/site/diyjunkie/ ... manual.pdf
I have all adjustments set per startup in the manual.
When I turn it on and it is warming up there is a dot in the center of the screen that quickly travels towards 7 - 8 o' clock then off the screen.
I tried hooking up a 3 vac transformer to play around with it also tried a square wave 555 circuit but had no luck getting it to do much with either.
I would love to have a working scope because I think it would be a great learning tool.
Do you think mine is worth trying to repair? I would hate to spend a bunch of cash and time on it only to be disapointed later.
- analogguru
- Old Solderhand
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If you expierience it as fun to play around with old tube equipment: yesDo you think mine is worth trying to repair?
From an ecomonical viewpoint: no
analogguru
There´s a sucker born every minute - and too many of them end up in the bootweak pedal biz.
- RLBJR65
- Resistor Ronker
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Thanks analogguru that’s what I figured and I guess that is my dilemma, I want to fix it but...
Guess I'll open it up and poke around a bit
Do you have any recomendations as to how I should proceed or what to check out first?
Guess I'll open it up and poke around a bit
Do you have any recomendations as to how I should proceed or what to check out first?
- modman
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I'm still reading that little book, but some more questios that are not addressed there:
If I buy a scope without probes, how do I find ones that match? Is there a standard for connecting the probes?
Do modern oscilloscope allow for calibration/setting up if necessary? A lot of 'untested' items on ebay...
If I buy a scope without probes, how do I find ones that match? Is there a standard for connecting the probes?
Do modern oscilloscope allow for calibration/setting up if necessary? A lot of 'untested' items on ebay...
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- analogguru
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I am very busy at the moment, must have a look at the schematic first...RLBJR65 wrote:Do you have any recomendations as to how I should proceed or what to check out first?
You can buy every probe that has at least the same upper frequency than the scope.... for audio frequencies unimportant.modman wrote:If I buy a scope without probes, how do I find ones that match?
The old standard (up to the sixties) was two banana plugs - the new standard is one BNC-plug.modman wrote: Is there a standard for connecting the probes?
The probes normally allow this - there is a little trimmer inside the probe. The calibration is done (on Hameg scopes) with the build in square-wave generator.modman wrote: Do modern oscilloscope allow for calibration/setting up if necessary?
analogguru
There´s a sucker born every minute - and too many of them end up in the bootweak pedal biz.
- RLBJR65
- Resistor Ronker
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Thanks analogguru.
I think I figured a plan.
1: Pull all the tubes and test them.
2: Replace tubes as needed. I've got about half of them anyway. Most are used but good.
3: Check and or replace the electrolytic caps in the horizontal circuit.
Hopefully that will get me going without spending a ton of money.
Sorry for hijacking the thread Modman!
I have another book around someware that has add on test circuits etc. for oscilloscopes when I find it I'll scan and post it too.
I think I figured a plan.
1: Pull all the tubes and test them.
2: Replace tubes as needed. I've got about half of them anyway. Most are used but good.
3: Check and or replace the electrolytic caps in the horizontal circuit.
Hopefully that will get me going without spending a ton of money.
Sorry for hijacking the thread Modman!
I have another book around someware that has add on test circuits etc. for oscilloscopes when I find it I'll scan and post it too.
- modman
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[quote="RLBJR65"
Sorry for hijacking the thread Modman! [/quote]
Hey, R, don't worry - it's relevant discussion, because tube scopes cost nothing nowadays - nobody wants to bother with them it seems. If you keep us updated on your endeavours.
Anyway, I went the a bit less cheaper way, but I think I scored well with a 2 channel 20Mhz scope for 38,50 EUR and it seems to work (let's find out when I get it.)
Sorry for hijacking the thread Modman! [/quote]
Hey, R, don't worry - it's relevant discussion, because tube scopes cost nothing nowadays - nobody wants to bother with them it seems. If you keep us updated on your endeavours.
Anyway, I went the a bit less cheaper way, but I think I scored well with a 2 channel 20Mhz scope for 38,50 EUR and it seems to work (let's find out when I get it.)
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- DiscoFreq
- Resistor Ronker
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Good place for my question!
I have a vintage Polish mini-scope, but no probes, can I use anything for that? I bought it a year ago (or longer) but still didn't test it
(I wanted to build it into my modular synth, it's the perfect size for that: about 5U high )
picture is not mine, but same model...
I have a vintage Polish mini-scope, but no probes, can I use anything for that? I bought it a year ago (or longer) but still didn't test it
(I wanted to build it into my modular synth, it's the perfect size for that: about 5U high )
picture is not mine, but same model...
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- Dirk_Hendrik
- Old Solderhand
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Great spot for my question too!!
Could you (modman) please adapt your explanations so they're usable for my daily bread and butter over the last 2 years:
(4Ghz bandwith, Mhz bandwith starts to feel like DC then )
Could you (modman) please adapt your explanations so they're usable for my daily bread and butter over the last 2 years:
(4Ghz bandwith, Mhz bandwith starts to feel like DC then )
- RLBJR65
- Resistor Ronker
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I got mine FREE cant get any cheaper than that My parents moved into a smaller place so Dad gave me the scope a Heathkit capacitor substitution box, a Heathkit resistor sub box and a Micronta transistor tester like this one https://cgi.ebay.com/Transistor-Tester- ... 286.c0.m14 that I have not figured out how to use yet.RLBJR65 wrote:it's relevant discussion, because tube scopes cost nothing nowadays - nobody wants to bother with them it seems. If you keep us updated on your endeavours.
Anyway... I finally got around to checking the tubes. The 1X2A rectifier (V604) that supplies -1400v to the picture tubes plate is bad. It tested at 60% or so also the gas and short lights were flickering. All the other tubes tested at 85% or better! At my favorite surplus store I picked up an NOS 1X2A for 2 bucks
Hopfully I will get a chance to put it back together and try it out this weekend.