Author Topic: Digital oscilloscope project/kit  (Read 124481 times)

RobWilson

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Re: Digital oscilloscope project/kit
« Reply #125 on: January 02, 2016, 10:14:11 AM »

Offline modeng200023

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Re: Digital oscilloscope project/kit
« Reply #126 on: January 02, 2016, 12:59:51 PM »
Thanks Rob, I think I'll have some fun.

John

Offline John Swift

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Re: Digital oscilloscope project/kit
« Reply #127 on: January 05, 2016, 03:36:49 PM »
Hi Rob

a simple LED oscilloscope from 20 years ago

the circuit shows the principle

the 'scope in the  photo has an adjustable sync  , time base and attenuator
as expected in a usable  tool
the oscilloscope is usable up to 30 KHz

    John


Offline John Rudd

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Re: Digital oscilloscope project/kit
« Reply #128 on: January 05, 2016, 03:43:57 PM »
John,
There arent any valves in that design..... :lol:
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Offline John Swift

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Re: Digital oscilloscope project/kit
« Reply #129 on: January 05, 2016, 03:52:33 PM »


Hi  John

    your correct ,
I did not go back to the old all valve Heath Kit oscilloscopes or Practical Wireless projects

they don't work with just a pp3 battery

     John

Offline Bluechip

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Re: Digital oscilloscope project/kit
« Reply #130 on: January 05, 2016, 04:12:49 PM »
I have a few modest talents. Knowing what I'm doing isn't one of them.

Offline John Rudd

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Re: Digital oscilloscope project/kit
« Reply #131 on: January 05, 2016, 04:17:02 PM »
If you care for a quick wallow in nostalgia:

https://archive.org/stream/PracticalWireless1971April#page/n25/mode/2up        :thumbup:

Dave

Yup, remember that well......iirc there was another scope in one of the other periodicals a couple of years earlier....Radio Constructor? Used a 1CP1 crt....iirc..

I love nostalgia and wallowing....
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Offline awemawson

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Re: Digital oscilloscope project/kit
« Reply #132 on: January 05, 2016, 04:34:20 PM »
Made my first oscilloscope when I was at school based on an ex WW2 VCR97 radar tube 6" diameter. Drove the metal working instructor mad pestering him to help me make the chassis and front panel. Used many of the ubiquitous EF50 red metal canned valves that the surplus shops were awash with at the time

http://www.r-type.org/exhib/aaj0166.htm

http://www.dos4ever.com/EF50/EF50.html

It worked ok but the frequency response was pretty low at about 1Mhz
Andrew Mawson
East Sussex

Offline sparky961

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Re: Digital oscilloscope project/kit
« Reply #133 on: January 05, 2016, 11:09:27 PM »
Hi, just a quick pic of my test board.
it's not too bad, at least the LED works. :zap:
Roy.

Seems a little Rube Goldberg if you ask me... ;)

Offline Bluechip

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Re: Digital oscilloscope project/kit
« Reply #134 on: January 06, 2016, 02:21:18 AM »

I love wallowing....


You  be careful. I reckon it was too much wallowing in my younger days that did my back in.  :ddb:

Dave
I have a few modest talents. Knowing what I'm doing isn't one of them.

RobWilson

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Re: Digital oscilloscope project/kit
« Reply #135 on: January 06, 2016, 02:34:29 PM »
Hi Rob

a simple LED oscilloscope from 20 years ago

the circuit shows the principle

the 'scope in the  photo has an adjustable sync  , time base and attenuator
as expected in a usable  tool
the oscilloscope is usable up to 30 KHz

    John



Hi John ,  Did you build one ? 


Looks a fun project , I may have a bash at making one myself   :zap: 



Its good to see this old time technologie , all way way before my time    :lol: :lol:                 cheers for sharing lads  :thumbup:


Rob

Offline wheeltapper

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Re: Digital oscilloscope project/kit
« Reply #136 on: January 06, 2016, 03:27:03 PM »
Hi Rob.
I've just finished building the scope kit and it all seems to work OK apart from one thing, the top l/h switch for AC, DC and ground, I can only get the display to indicate DC or ground.
have you any ideas what to look for?

cheers
Roy.
I used to be confused, now I just don't know.

Offline kayzed1

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Re: Digital oscilloscope project/kit
« Reply #137 on: January 06, 2016, 04:01:13 PM »
My kit arrived today, will take a look at it in the morning and report back.
Lyn.

Offline John Rudd

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Re: Digital oscilloscope project/kit
« Reply #138 on: January 06, 2016, 05:21:52 PM »
How long does it take for a kit to arrive?

Might just buy one for fun... :coffee: I already have a digital lcd scope...... :scratch:
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RobWilson

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Re: Digital oscilloscope project/kit
« Reply #139 on: January 06, 2016, 05:49:24 PM »
Hi Rob.
I've just finished building the scope kit and it all seems to work OK apart from one thing, the top l/h switch for AC, DC and ground, I can only get the display to indicate DC or ground.
have you any ideas what to look for?

cheers
Roy.

Hi Roy

All I can think of is you may have a faulty switch  ,



From pin 2 on the back of the board to the outer of the BNC plug ,

 


With the switch  in the Ground position you should have continuity .



 

In AC or DC there will be a high resistance , if you still have continuity in these positions the switch is bust. 



DSO  Manual attached for the pros to cast an eye over .


Hope that helps ,Rob 

Offline wheeltapper

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Re: Digital oscilloscope project/kit
« Reply #140 on: January 06, 2016, 05:55:14 PM »
How long does it take for a kit to arrive?

Might just buy one for fun... :coffee: I already have a digital lcd scope...... :scratch:

Mine arrived within a week. ordered on 21-12, e-mail saying it was dispatched 22-12, arrived a few days later.
I got mine from here
http://www.ebay.co.uk/itm/131575205359

Roy.
I used to be confused, now I just don't know.

RobWilson

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Re: Digital oscilloscope project/kit
« Reply #141 on: January 06, 2016, 05:58:48 PM »
How long does it take for a kit to arrive?

Might just buy one for fun... :coffee: I already have a digital lcd scope...... :scratch:


You know you want to John  :poke:  ,,,,,,,,,,,,,,,,,,,,,,join the fun  :lol:



Rob

4 weeks from banggood  :palm:

Offline wheeltapper

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Re: Digital oscilloscope project/kit
« Reply #142 on: January 06, 2016, 06:06:29 PM »
Rob,
I just checked the switch and I get what you say on pin 2, continuity to ground, high resistance on AC or DC.
why is there an arrow pointing to pin 4?

Roy.
I used to be confused, now I just don't know.

RobWilson

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Re: Digital oscilloscope project/kit
« Reply #143 on: January 06, 2016, 06:23:15 PM »
Rob,
I just checked the switch and I get what you say on pin 2, continuity to ground, high resistance on AC or DC.
why is there an arrow pointing to pin 4?

Roy.


Hi Roy

 Pin 4 is connected to BNC outer ,it was easier/clearer  to use a crock clip on the connector and take the photo .

So its not the switch then . mmmmmmmm


Rob



Offline John Swift

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Re: Digital oscilloscope project/kit
« Reply #144 on: January 06, 2016, 06:26:16 PM »
Hi Rob

just got back from the Everton v Manchester City match    (we won 2-1)

no I didn't build the LED scope
 I built a Vellerman LCD scope about 12 years ago
I've not used it for a while it needs the  6  AA nicads replacing

   John


« Last Edit: January 06, 2016, 11:11:46 PM by John Swift »

Offline John Swift

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Re: Digital oscilloscope project/kit
« Reply #145 on: January 06, 2016, 07:16:03 PM »
Hi Roy

just double checking
when you say I can only get the display to indicate DC or ground.

do you mean it does not show "AC" at the bottom of the LCD
or the trace is a straight line

if its not indicating "AC" at the bottom of the LCD then check the voltage at test point TP6  ( switch 1B terminal 6 )
+5V for DC
 +1.2V  for AC
and 0V for GND

if its the trace not responding
check C1 is 0.1uF (marked 104)
if for instance a very small value capacitor that should be C2 , C3 , C5 or C7
virtually non of the AC voltage at the input connector will be passed onto  switch 1A terminal 3

   John

Offline wheeltapper

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Re: Digital oscilloscope project/kit
« Reply #146 on: January 07, 2016, 06:07:18 AM »
Hi John, thanks for the reply.

It is the indicator on the LCD, it doesn't change to AC.

I was going to do some voltage checks as soon as real life gets out of the way. :bang:
I'll get back with the results.

Cheers
Roy.
I used to be confused, now I just don't know.

Offline wheeltapper

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Re: Digital oscilloscope project/kit
« Reply #147 on: January 07, 2016, 06:24:42 AM »
Thar's interesting, I'm getting 3.8v on AC.

I will look further.

Roy.
I used to be confused, now I just don't know.

Offline Will_D

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Re: Digital oscilloscope project/kit
« Reply #148 on: January 07, 2016, 07:31:55 AM »
DSO  Manual attached for the pros to cast an eye over .
Hope that helps ,Rob
Cheers Rob for posting the manual.

 I must say that is one of the best manuals I've seen in a while for such a cheap kit!.
Engineer and Chemist to the NHC.ie
http://www.nationalhomebrewclub.ie/forum/

Offline John Rudd

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Re: Digital oscilloscope project/kit
« Reply #149 on: January 07, 2016, 07:37:33 AM »
3.8v is too high....should be around 1.4v.....it looks like the software isnt switching as a result...

I suspect the resistors are the wrong way round....

You need to check the values of the resistors in the chain......
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