Protek P-2020 20MHZ oscilloscope

metron9

I was talking to a friend of mine and mentioned I was looking for an occilloscope He said take this dusty old thing and play with it

Alas no manual and I am a noobe at this.

Can anyone tell me what to set it and how to measure say the voltage on a blinking LED? or some pulseout signals from the BS2?

For now I just want to do something simple.

Thanks

Chris Savage

metron9,

·· You should be able to Google for a tutorial on using a scope.· You can always check out our docs on the USB Scope!· Might make you want to buy one!· · With the kit you get examples and everything!

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Chris Savage
Parallax Tech Support
csavage@parallax.com

Beau Schwabe

metron9,
Your in luck...··The scope that I "grew up on" was a P-3502 which is very close
What I would probably do first is to buy some "new" test leads.
Next I would self-calibrate the thing just to make sure that it is working.

Self Calibrate:
 1)Set VOLTS/DIV to .5V or 50mV (depending on if you have a X1 or a X10 test lead)
 2)Set TIME/DIV to .5mS
 3)Flipt the trigger source to INT and the coupling to AC
 4)Clip the probe to the CAL terminal (just to the right of the FOCUS)
 5)Flip the CH1 switch to GND and adjust the position so that the "CENTER" of the trace
   just crosses the Vertical and Horizontal cross hair ticks on the scope.
 6)Adjust TRACE ROTATION until the "ENDS" of the trace are level with the Horizontal cross hair. (Repeat steps 4 & 5 as needed)
 7)Flip the CH1 switch to DC
 8)Adjust the fine control on the VOLTS/DIV and the TIME/DIV so that each RISE/FALL time and distance between each pulse ALL occupy 1 DIVision.(see image)

If you look here:

http://www.protektest.com/ProdDnLd.asp?type=MANUAL

...look for P3502C, this will be the closest to your P2020 and should contain most of the information you will need.



··················






▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Beau Schwabe

IC Layout Engineer
Parallax, Inc.

metron9

That all worked except for the setting of CH1 to Ground, I get no signal with the red lead connected to the cal when set on ground only AC or DC

Something wrong with it?

Beau Schwabe

Step #7 has you flipping the switch to DC. Setting the channel to ground is just part of the calibration to level the horizontal.
You should get a "flat line" in the DC mode, try adjusting the trigger or press the AUTO/NORMAL button in the trigger section
if you don't see a flat line. Anytime you change the physical position of the scope you should do this because the magnetic
field of the earth can have an effect as well as other surroundings.

I still would invest in a nice set of probes.

The calibration image looks about right... a little long in the TIME domain, but nothing serious

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Beau Schwabe

IC Layout Engineer
Parallax, Inc.

Post Edited (Beau Schwabe (Parallax)) : 8/27/2005 6:01:52 AM GMT

metron9

Well I wondered what the squiggly lines really mean so I wrote a little LED program and hooked up the probe
Its set at 5MS Time sweep, The upper line shows 5,4,3,2, and 1 ms pin ON the off cycle is 1ms, at the end is a 5ms wait

I am trying to figure out how to generate a sine wave but alas its 1:00 am again and I better hit the rack. Thanks for the help.
I will post my first generated sign wave when I figure it out, Capacitors will be involved I bet. This is so cool....
I bet I could do timimg studys on individual basic commands during run time, I'll bet you can catch fish with this thing..... whoa....

Mloop:

 Set Portc.5
 Waitms 5
 Reset Portc.5
 Waitms 1
  Set Portc.5
 Waitms 4
 Reset Portc.5
 Waitms 1
 Set Portc.5
 Waitms 3
 Reset Portc.5
 Waitms 1
 Set Portc.5
 Waitms 2
 Reset Portc.5
 Waitms 1
 Set Portc.5
 Waitms 1
 Reset Portc.5
 Waitms 1
 Waitms 10

Goto Mloop

Beau Schwabe

The "squiggly lines" are PWM signals. If you were using a stamp or SX, which I'm not sure you are based on your code, there
is an example under the PWM command in the manual using a resistor value of 10K and capacitor value of 0.1uF to convert the
PWM signal into a pseudo analog signal.

BTW) 2:00am here ( baby duty tonight )

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Beau Schwabe

IC Layout Engineer
Parallax, Inc.

metron9

I have already put it to good use, I have a project I am working on where a switch was giving me false signals, I can see with the scope that about a 4 ms high is a very good trigger level, so I will adjust my software to poll for 3 ms when triggered and ignore the less than 3, something like that. Yes this is cool it's a window to the invisible world and I think I'm hooked on this stuff... Gnight