Oscilloscopes

On a sunny day (Fri, 15 Aug 2014 02:15:25 -0700 (PDT)) it happened
meow2222@care2.com wrote in
<d043dda4-baef-43d2-b5eb-a8b2e7c94c52@googlegroups.com>:

>On Friday, August 15, 2014 7:56:06 AM UTC+1, Jan Panteltje wrote:
>> On a sunny day (Thu, 14 Aug 2014 15:59:29 -0700 (PDT)) it happened
>> meow2222@care2.com wrote in
>> <4b3243d3-4483-4087-ae8f-58e271f1c731@googlegroups.com>:
>> >On Thursday, August 14, 2014 11:49:38 PM UTC+1, trevor...@gmail.com wrote:
>> >
>> >> Hi I have just started in electronics and have started to think about get=
>> >ting an oscilloscope. I don't have enough money for the $400 digital oscill=
>> >oscopes. My family does not have a lot of money and the ones on ebay are st=
>> >ill too much expensive. I'm just wondering if anyone has an old analog osci=
>> >lloscope that I could have. Thanks :)
>> >
>> >Ebay does. Until then there's free soundcard scope software. You can also u=
>> >se a dead CRT tv as a crude scope, but beware of overheating the crt neck b=
>> >y overscanning.
>
>> It probably will burn in in a second if you do not turn brighness way down.
>> Maximum f on the V coils even with a good amp would be maybe a kHz,
>> or wind your own coils.
>> better build this:
>>  http://panteltje.com/panteltje/pic/scope_pic/
>> I am not selling my 10 MHz analog scope for anything below 5000 Euro :-)
>> Nothing can replace that.
>> if he can get his hands on an old scope CRT he is already half way there,
>> I build several that way DG7-32 based and Russian CRT based.
>>  http://www.r-type.org/exhib/aar0022.htm
>>  http://www.ebay.com/itm/310682876427
>>   48$ 43 cents ex shipping
>
>Normal TV mode operation of the horizontal scan is about 15kHz plus lots of higher harmonics. You get 2 timebase frequencies
>depending which coil you connect to.
>
>Overscan can kill these things with a bang. Moving the scan coils forwards reduces the potential for it.

>NT

There is in that case a much simpler way that does not need any mods to the teefee,
If you are satisfied with the 15625 Hz sweep that is.

Make a free running V and V generator linear ramp.
Compare to 2 voltages, one a pot DC level (horizontal position), the other the input signal (vertical position).
AND the outputs of the 2 comparators.
Make sync pulse from H and V down going ramp.
Add output of AND gate on top of that sync.
Feed to video input teefee or some RF modulator input and then in antenna input teefee.
I'v done this, displayed 500kHz square qwave TTL with the >> MHz spikes.
But then your source needs to be in sync with the H osc, or sync the H osc to a fraction of the input signal.
Works great.
The idea behind it is from old teefee 'trick generator', you create a dot on the screen (video),
and can move the position of the dot.
For very LF demos it is great too,
Cost just a few transistors, I used UJTs and PNP current sources for the ramp generators,
and diodes for the and gate, and BFY90 transistors diff pairs for the comparators.
I demoded it to somebody, and later heard somebody made a product of it, probably patented it hahahaha.
Anyways that was 1976 or there about.

On Friday, August 15, 2014 1:15:41 PM UTC+1, Jan Panteltje wrote:
> On a sunny day (Fri, 15 Aug 2014 02:15:25 -0700 (PDT)) it happened
> 
> meow2222@care2.com wrote in
> 
> <d043dda4-baef-43d2-b5eb-a8b2e7c94c52@googlegroups.com>:
> 
> 
> 
> >On Friday, August 15, 2014 7:56:06 AM UTC+1, Jan Panteltje wrote:
> 
> >> On a sunny day (Thu, 14 Aug 2014 15:59:29 -0700 (PDT)) it happened
> 
> >> meow2222@care2.com wrote in
> 
> >> <4b3243d3-4483-4087-ae8f-58e271f1c731@googlegroups.com>:
> 
> >> >On Thursday, August 14, 2014 11:49:38 PM UTC+1, trevor...@gmail.com wrote:
> 
> >> >
> 
> >> >> Hi I have just started in electronics and have started to think about get=
> 
> >> >ting an oscilloscope. I don't have enough money for the $400 digital oscill=
> 
> >> >oscopes. My family does not have a lot of money and the ones on ebay are st=
> 
> >> >ill too much expensive. I'm just wondering if anyone has an old analog osci=
> 
> >> >lloscope that I could have. Thanks :)
> 
> >> >
> 
> >> >Ebay does. Until then there's free soundcard scope software. You can also u=
> 
> >> >se a dead CRT tv as a crude scope, but beware of overheating the crt neck b=
> 
> >> >y overscanning.
> 
> >
> 
> >> It probably will burn in in a second if you do not turn brighness way down.
> 
> >> Maximum f on the V coils even with a good amp would be maybe a kHz,
> 
> >> or wind your own coils.
> 
> >> better build this:
> 
> >>  http://panteltje.com/panteltje/pic/scope_pic/
> 
> >> I am not selling my 10 MHz analog scope for anything below 5000 Euro :-)
> 
> >> Nothing can replace that.
> 
> >> if he can get his hands on an old scope CRT he is already half way there,
> 
> >> I build several that way DG7-32 based and Russian CRT based.
> 
> >>  http://www.r-type.org/exhib/aar0022.htm
> 
> >>  http://www.ebay.com/itm/310682876427
> 
> >>   48$ 43 cents ex shipping
> 
> >
> 
> >Normal TV mode operation of the horizontal scan is about 15kHz plus lots of higher harmonics. You get 2 timebase frequencies
> 
> >depending which coil you connect to.
> 
> >
> 
> >Overscan can kill these things with a bang. Moving the scan coils forwards reduces the potential for it.
> 
> 
> 
> >NT
> 
> 
> 
> There is in that case a much simpler way that does not need any mods to the teefee,
> 
> If you are satisfied with the 15625 Hz sweep that is.
> 
> 
> 
> Make a free running V and V generator linear ramp.
> 
> Compare to 2 voltages, one a pot DC level (horizontal position), the other the input signal (vertical position).
> 
> AND the outputs of the 2 comparators.
> 
> Make sync pulse from H and V down going ramp.
> 
> Add output of AND gate on top of that sync.
> 
> Feed to video input teefee or some RF modulator input and then in antenna input teefee.
> 
> I'v done this, displayed 500kHz square qwave TTL with the >> MHz spikes.
> 
> But then your source needs to be in sync with the H osc, or sync the H osc to a fraction of the input signal.
> 
> Works great.
> 
> The idea behind it is from old teefee 'trick generator', you create a dot on the screen (video),
> 
> and can move the position of the dot.
> 
> For very LF demos it is great too,
> 
> Cost just a few transistors, I used UJTs and PNP current sources for the ramp generators,
> 
> and diodes for the and gate, and BFY90 transistors diff pairs for the comparators.
> 
> I demoded it to somebody, and later heard somebody made a product of it, probably patented it hahahaha.
> 
> Anyways that was 1976 or there about.

I like that idea :) Maybe will try to do something with it when I get one of those round tuits, thanks.


NT

On a sunny day (Fri, 15 Aug 2014 05:58:04 -0700 (PDT)) it happened
meow2222@care2.com wrote in
<6b305665-36c5-4783-a500-4d272888188d@googlegroups.com>:

>I like that idea :) Maybe will try to do something with it when I get one of those round tuits, thanks.

Here is the circuit diagram as far as I remember..
 http://panteltje.com/pub/TV_scope_IMG_4506.JPG

There are a few not so obvious tricks in here.
The 2 diff amplifiers are in balance when he ramps on the input equals the voltage on the H and V position potmeters (or V input signal).
In that case the collectors are high, and via diodes D1,2,3,4 point A and point C the base of Q6 is high, 'white'.
In ANY other case one of the collectors of Q3,Q5 and / or Q10., Q12 is lower, and the base of Q6 is less positive (pulled a bit down), so black.
So there are basically 2 window comparators, anded with the diodes.
the size of the windows, this is the H and V size of the white spot, is set by the current sources of the diff amps.
 
The sync happens when the UJTs discharge the caps, and drive Q9 low, this will pull the output low.

Do not remember exact component values.
If you cannot figure it out I can enter it in LTspice one day, should run just like that (has spice UJTs?).

I have drawn Y input via a cap, but of course it is basically DC coupled, add a FET perhaps.
Q1 Q7 are current sources just to make linear ramps.

This was about that circuit, give or take a resistor or something.
 

Paul E Bennett wrote:
> trevordally23@gmail.com wrote:
> 
>> Hi I have just started in electronics and have started to think about
>> getting an oscilloscope. I don't have enough money for the $400 digital
>> oscilloscopes. My family does not have a lot of money and the ones on ebay
>> are still too much expensive. I'm just wondering if anyone has an old
>> analog oscilloscope that I could have. Thanks :)
> 
> If you had asked a year ago and paid the shipping I could have helped 
> myself. Do some research on your local Amateur Radio Groups and asked around 
> that crowd. They often organise Radio Rallies and Hamfests where such items 
> are oftn bought and sold. Another place might be if you have a reasonably 
> local computer club who hold similar events.
> 

Yup, that's what I was going to suggest. Here is how to find the local club:

http://www.arrl.org/find-a-club

All it may take is a phone call. Like Paul I had an analog scope from my
younger days in almost-as-new condition. Last year I donated it to a
school. Most serious radio hams have numerous scopes and would love to
give an older scope to the next generation.

-- 
Regards, Joerg

http://www.analogconsultants.com/

>"live in the U.S. State Minnesota. Hope it helps. "

Nope. I just for the hell of it did a web search for electronics surplus pl=
aces there and went to a few websites, and there ain't all tha tmuch.=20

Someone mentioned eBay, which is alright but you can't check things out bef=
ore buying. You get Craigslist there ? That can be a good source for some t=
hings, like scopes. Deal face to face and at least you can check the thing =
out.=20

Definitely get an old style analog scope, referred to as a CRO. Keep it sim=
ple. Try to get a trace on the screen that moves with the positioning contr=
ols fo less than fifty bucks. They are out there.=20

Textronix is the last word in analog scopes. However, a Tenma works just fi=
ne. The Tek will have a better trigger circuit, but other than that, the El=
 Chepo wil work just fine for most things. I would say get just about anyti=
ng, 15 or 20 mHz bandwith. That is plenty to learn on. I have an old 422 an=
d a Tenma 72 dash someting, and there is really not all that much difreence=
. Of course the old Tek can withstand a nuclear holocaust, but if that happ=
ens I don;t really care.=20

Or maybe we'll sell you the HP. Not top buck because it is not aful alignme=
nt and the dual timebase doesn't work. But it will come with a parts unit. =
At 275 mHz it is one of the fastest analog CROs ever built. Alot of the new=
er ones digitize the input and read it to the CRT at a slower speed. This i=
s one of the last "real" ones. Belongs to my partner, not sure what he woul=
d take for it but if interested ask and I will ask. The best scope we got r=
ight now, BUT, we are Tektronix people. The HP is a 1725a. I had to put the=
 vertical outpurt IC in it and then found the dual timebase doesn't work. D=
ecided I don't care and there it sits. You could probably take a board from=
 the parts ubit and et that function working. And then you have to learn ho=
w to use it. I wouldn't bother in the beginning. As a scope it already work=
s.

On Thu, 14 Aug 2014 15:49:38 -0700 (PDT), trevordally23@gmail.com
wrote:

>Hi I have just started in electronics and have started to think about getting an oscilloscope. I don't have enough money for the $400 digital oscilloscopes. My family does not have a lot of money and the ones on ebay are still too much expensive. I'm just wondering if anyone has an old analog oscilloscope that I could have. Thanks :)

Instead of begging, I suggest you do some odd jobs around your
neighborhood, save up about $100 and buy a Mini-DSO scope.  I see
single channel versions on sleazebay for around $70 and 4 channel ones
for around $150.

This is an open source design done by Seeed Studios and released to
the public.  Several chicom manufacturers have picked up on the design
and are making clones but I stick with the nice metal-cased Seeed
original.

I keep several around the lab.  The 4 channels are sometimes
invaluable and if I smoke one, no tears shed.

In fact, I have 4 channel one right now that has a low contrast screen
problem that I'll give you if you want to hack it and see what's
wrong.  get my email address from my website.  No scope probes
included - you'll have to buy those yourself (~$20) but then what do
you expect for free?

John
John DeArmond
http://www.neon-john.com
http://www.fluxeon.com 
Tellico Plains, Occupied TN
See website for email address

In article <eb3645b4-86de-495d-94ae-c5bd0893b97f@googlegroups.com>, 
trevordally23@gmail.com says...
> 
> I live in the U.S. State Minnesota. Hope it helps.


 You guys would drool over this, I still have one of these.
B & K 1403 in great shape!

https://www.flickr.com/photos/spike55151/207509920/

I have not turned it on for some time but I know it works..

Maybe I'll part with it :)

Jamie

On Fri, 15 Aug 2014 15:25:39 -0700 (PDT), jurb6006@gmail.com wrote:

>>"live in the U.S. State Minnesota. Hope it helps. "
>
>Nope. I just for the hell of it did a web search for electronics surplus places there and went to a few websites, and there ain't all tha tmuch. 
>
>Someone mentioned eBay, which is alright but you can't check things out before buying. You get Craigslist there ? That can be a good source for some things, like scopes. Deal face to face and at least you can check the thing out. 
>
>Definitely get an old style analog scope, referred to as a CRO. Keep it simple. Try to get a trace on the screen that moves with the positioning controls fo less than fifty bucks. They are out there. 
>
>Textronix is the last word in analog scopes. However, a Tenma works just fine. The Tek will have a better trigger circuit, but other than that, the El Chepo wil work just fine for most things. I would say get just about anyting, 15 or 20 mHz bandwith. That is plenty to learn on. I have an old 422 and a Tenma 72 dash someting, and there is really not all that much difreence. Of course the old Tek can withstand a nuclear holocaust, but if that happens I don;t really care. 
>
>Or maybe we'll sell you the HP. Not top buck because it is not aful alignment and the dual timebase doesn't work. But it will come with a parts unit. At 275 mHz it is one of the fastest analog CROs ever built. Alot of the newer ones digitize the input and read it to the CRT at a slower speed. This is one of the last "real" ones. Belongs to my partner, not sure what he would take for it but if interested ask and I will ask. The best scope we got right now, BUT, we are Tektronix people. The HP is a 1725a. I had to put the vertical outpurt IC in it and then found the dual timebase doesn't work. Decided I don't care and there it sits. You could probably take a board from the parts ubit and et that function working. And then you have to learn how to use it. I wouldn't bother in the beginning. As a scope it already works.

I still have my Tema, bought it new back in the 80's.
I see there are a few on ebay that command a fairly high price. WHat
is nice about it was the component Bannana input, makes checking
zeners easy.

Just be careful, some of the CRT's don't have the brightness they once
had.

Good thing is the manuals always had the schematics in them.

Cheers

Hi I just checked this and john I would like to have the oscilloscope and i'm wondering where on the website your email is? All of the emails are to fluxeon.com. I couldn't find the other site so i don't know if it was there.

On Sun, 17 Aug 2014 01:07:06 -0700 (PDT), trevordally23@gmail.com
wrote:

>Hi I just checked this and john I would like to have the oscilloscope and i'm wondering where on the website your email is? All of the emails are to fluxeon.com. I couldn't find the other site so i don't know if it was there.

My personal site is www.neon-john.com.  My email is jgd @
neon-john.com.

Send me postage for a small (video cassette size) Flat Rate Box and
your address to 

John DeArmond
PO box 545
Tellico Plains, TN 37385

I live on a remote mountaintop and only go to town about twice a
month.  Include your email address and I'll notify you when I send it.

John
John DeArmond
http://www.neon-john.com
http://www.fluxeon.com 
Tellico Plains, Occupied TN
See website for email address