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Kilowatt 3rd January 2002 06:34 AM

I don't own or have access to an oscilloscope, but I will desperately need one, especially when it comes time to make my big amp. I don't have the money for a new one. There are several ADCs that can be used with a computer and software to form a DSO. Does anyone know of such a thing for less than $300? Maybe even less than $200? By the way, I'm looking for one that can read signals up to almost 200V because I will be dealing with peak signal voltages up to almost 170V. Many such peices of hardware don't go that high. I don't want something with a crappy bandwidth either, and I want at least two channels. I'm sure many of you know what else to look for in a good scope better than I. Another option would be to build my own scope. I have several good CRTs laying around, and I might as well use one. They're all quite big though, and would make for a very cumbersome piece of equipment. Is there anywhere I can find all the information to do this? I have no idea what that would involve. It might be way too hard and/or too expensive.

Any recomendations?

daatkins 3rd January 2002 09:17 AM

I think your best bet would be ebay; there's always plenty of acceptable (read old analog) scopes available in the $100 - $200 range.

If you really want a DSO then the best option is a PC kit scope. The best I've found is...

The kit comes in various levels including fully built & tested. The complete kit of parts including pre-programmed ICs is about $250. I'm not sure if it will allow 200v, although a 10:1 probe would help a lot here.

Nice one.

relder 8th January 2002 06:55 PM

For less than $300 you can get a new analog scope:

Kilowatt 5th February 2002 02:02 AM

:eek: First of all, I'm quite sure that this thread used to be much longer. I don't know what happened to most of the posts here.

Anyway, I just got a Paco S-50 oscilloscope for $15 from a friend who got it from a friend of his. It's somewhat of a miracle that he had one, he didn't even know what it was. The thing is older than old, it uses vacuum tubes. So, does anyone know anything about this model? specs? Maybe someone on the forum owns one and can tell me something about it. :)

subwo1 5th February 2002 02:22 AM

Kilowatt, it probably has a band-width of around 500khz. But it is way better than nothing. Those are the same type of scopes I used for a long time.

Kilowatt 5th February 2002 02:28 AM

Yeah, better than nothing, and a good price too.

Kilowatt 5th February 2002 04:18 AM

The controls on that old scope are vastly different from modern scopes, I have no idea how to use it. I am having trouble finding info on the internet about such dinosaurs.

Here's all the controls and things it has:

Intensity (and "off")
V. Position
H. Position
V. Gain
H. Gain
Sweep Vernier
Sweep Selector (ext. sweep, line freq., 20-120CPS, 120-1400CPS, 1.4KC 20KC, 20KC 150KC)
Line Phasing
Sync. Lock
Sync Selection (Ext., Line, Int)
1V P-P screen cal. (on, off)
Attenuation (1x, 10x, 100x, of course)
Horiz. input (screw terminal)
Vert. input (screw terminal)
Ext. Sync. (seems to be a banana plug or 1/8" phone jack, can't tell which)
Vert (ext., int. (a swich on the back))
two unmarked screw terminals are located next to that last switch.

Many of these are not familiar, an not found on scopes that I've seen before, others that are on most scopes are not present. I'd like to know what they all do. Thanks.

subwo1 5th February 2002 07:05 AM

Intensity (and "off"): Adjusts trace brightness and power on/off
Focus: Adjusts trace sharpness
V. Position: Shifts trace up or down
H. Position: Shifts the trace left or right
V. Gain:Continous adjustment of vertical input signal
H. Gain:Expands or contracts trace horizontally
Sweep Vernier:continous adjustment of time base
Sweep Selector (ext. sweep, line freq., 20-120CPS, 120-1400CPS, 1.4KC 20KC, 20KC 150KC):time base selection
Line Phasing:Guess--adjusts phase of 60 cycle line signal when used for sync
Sync. Lock:Guess--enables sync lock.
Sync Selection (Ext., Line, Int):Choose source of sync signal
1V P-P screen cal. (on, off)Vertical reference for comparison.
Attenuation (1x, 10x, 100x, of course)
Horiz. input (screw terminal): Bananna jack(BJ) which connects directly to horzontal amp when frequency selctor is set to X/Y.
Vert. input (screw terminal):Same as above for vertical.
Ext. Sync. (seems to be a banana plug or 1/8" phone jack, can't tell which)BJ to input input external sync signal if selcted.
Vert (ext., int. (a swich on the back))
two unmarked screw terminals are located next to that last switch.: These BJs allow direct access to the horizontal and vertical deflection plates when that switch is thrown.

I hope these descriptions are helpful.

Kilowatt 6th February 2002 12:30 AM

Thanks, but I've played around with it a little, and found out some of that on my own by now. You did clear up some unknown things though.

Anyway, it seems to work, but it gets a little unstable sometimes when it's warmed up. Sometimes a rapidly fluctuatinging waveform with countless phases appears on the screen and none of the controls will correct it, you just have to wait for it to go away, and sometimes, a single or multiphase wave uncontrollably climbs the screen at an angle. It seems that it could use a few replacement tubes, it's probably around 50 years old. I just happen to have a large case full of many assorted tubes, because my grandfather was a repairman back in the tube days, and I can replace most of the tubes in the scope with the selection I have, but none of them seem to solve the problems, so apparently it wants one of the ones I don't have. It does at least work though.

subwo1 6th February 2002 01:02 AM

Sounds like you might want to check the electrolytic capacitors for having dried out. Other capacitor types may cause some trouble also. you may just want to start replacing caps.

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