EEVblog Electronics Community Forum
Products => Test Equipment => Topic started by: Sam__ on February 15, 2013, 08:25:26 pm
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I am looking to buy my first oscilloscope. I have quite a low budget, around £60 is my maximum. I managed to find an old analog Advance OS250 Oscilloscope, circa mid to late 70s I believe, which I can get for >£50. The only problem is it's 10Mhz, which really doesn't seem like much compared to the usual 20/50Mhz.
Here is the manual as I'm not sure what else is important bar the bandwidth and number of channels.
http://bama.edebris.com/download/advance/os250/Oscilloscope_-_Advance_OS250_10Mhz_Dual_Trace.pdf (http://bama.edebris.com/download/advance/os250/Oscilloscope_-_Advance_OS250_10Mhz_Dual_Trace.pdf)
I'm planning on building some of my own power supplies and it would be great if I could use the scope to analyse the noise on the output. It will just be used as a general scope, as of now I've not done any RF work so I don't think I need massive bandwidth although I do work with micro controllers and have heard it's useful to have a scope to analyse the pin outs.
Any and all advice is welcome, thank you in advance.
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Yep, good starter - just check if you can find a similar scope for less ££.
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I've been watching ebay for a while and the 20Mhz scopes seem to be going for around 60-70 which is a little beyond my budget, I could stretch if I have to but not if I can help it.
with regards to the age of the unit, is that a potential issue as to it's potential life expectancy?
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"with regards to the age of the unit, is that a potential issue as to it's potential life expectancy?"
Yes, and no. Expect that some parts are faulty or likely to fail soon. But then you have something to study and fix. Studying and fixing a scope will give you lots of experience. If you fix the one component that is faulty, the life expectancy of the scope is expanded, of course. As long as you can replace the faulty parts, it will last forever... Usually it is just a troublesome solder joint or a dirt cheap resistor or a easily replacable transistor that fails. Sometimes it costs a little more i.e. if a $50 nuvistor is blown.
Search the internet, and primarily buy stuff that is widely known with lots of info, like schematics, user manuals, calibration manuals, etc.
You should probably save some money for some more recent gear...
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Well it looks like I'm in luck. After about a month of not winning items on ebay I managed to nab myself Topward 7021 20Mhz scope!
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So now I'm looking forward to receiving my scope sometime soon I should get some probes. Only problem is I don't know too much about them. I've researched a little about the capacitance and x1 and x10 modes. Only problem is I have no idea how to tell if a certain type of probe is suitable to my needs.
The input capacitance of the scope is 25pF, does this effect my choice of probe or can I just adjust it?
I found some on ebay which are fairly cheap - http://www.ebay.co.uk/itm/2-PCS-40MHZ-x10-x1-Oscilloscope-Clip-Probes-Scope-Kit-/250880988259?pt=UK_BOI_Electrical_Test_Measurement_Equipment_ET&hash=item3a69ac1463 (http://www.ebay.co.uk/itm/2-PCS-40MHZ-x10-x1-Oscilloscope-Clip-Probes-Scope-Kit-/250880988259?pt=UK_BOI_Electrical_Test_Measurement_Equipment_ET&hash=item3a69ac1463)
would they work or do I need a certain spec?
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I'm planning on building some of my own power supplies and it would be great if I could use the scope to analyse the noise on the output.
I see your dilemma but I want to be %100 honest with you.
I don't think that it's possible to use this scope for power electronic circuits. Switching power supplies may seems to working at low frequency but in fact they are not. You need at least 100MHz scope to debug 100kHz ZVC circuit. (Preferably 200MHz)
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I'm planning on building some of my own power supplies and it would be great if I could use the scope to analyse the noise on the output.
I see your dilemma but I want to be %100 honest with you.
I don't think that it's possible to use this scope for power electronic circuits. Switching power supplies may seems to working at low frequency but in fact they are not. You need at least 100MHz scope to debug 100kHz ZVC circuit. (Preferably 200MHz)
Ah okay, thanks for the information. I'm not too bothered about that but it's good to know.
Anyone have any advice on probes?
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So now I'm looking forward to receiving my scope sometime soon I should get some probes. Only problem is I don't know too much about them. I've researched a little about the capacitance and x1 and x10 modes. Only problem is I have no idea how to tell if a certain type of probe is suitable to my needs.
The input capacitance of the scope is 25pF, does this effect my choice of probe or can I just adjust it?
I found some on ebay which are fairly cheap - http://www.ebay.co.uk/itm/2-PCS-40MHZ-x10-x1-Oscilloscope-Clip-Probes-Scope-Kit-/250880988259?pt=UK_BOI_Electrical_Test_Measurement_Equipment_ET&hash=item3a69ac1463 (http://www.ebay.co.uk/itm/2-PCS-40MHZ-x10-x1-Oscilloscope-Clip-Probes-Scope-Kit-/250880988259?pt=UK_BOI_Electrical_Test_Measurement_Equipment_ET&hash=item3a69ac1463)
would they work or do I need a certain spec?
They refer 25pF is within their compensation range at page bottom in your link. I have the 100MHz same construction probes for my analog scope and general use for some years now. They are rugged enough and the hook holds well.
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Good to hear they've lasted you a while, I was worried the build quality wouldn't be very good.
So now I'm looking forward to receiving my scope sometime soon I should get some probes. Only problem is I don't know too much about them. I've researched a little about the capacitance and x1 and x10 modes. Only problem is I have no idea how to tell if a certain type of probe is suitable to my needs.
The input capacitance of the scope is 25pF, does this effect my choice of probe or can I just adjust it?
I found some on ebay which are fairly cheap - http://www.ebay.co.uk/itm/2-PCS-40MHZ-x10-x1-Oscilloscope-Clip-Probes-Scope-Kit-/250880988259?pt=UK_BOI_Electrical_Test_Measurement_Equipment_ET&hash=item3a69ac1463 (http://www.ebay.co.uk/itm/2-PCS-40MHZ-x10-x1-Oscilloscope-Clip-Probes-Scope-Kit-/250880988259?pt=UK_BOI_Electrical_Test_Measurement_Equipment_ET&hash=item3a69ac1463)
would they work or do I need a certain spec?
They refer 25pF is within their compensation range at page bottom in your link. I have the 100MHz same construction probes for my analog scope and general use for some years now. They are rugged enough and the hook holds well.