I Met My Old Buddy - Page 1
Forum section: electronics / general

author: Mechatrommer
author_rank: Super Contributor
timestamp: April 04, 2011, 03:36:12 am
content: today my colleague asked me to show her how to setup an oscilloscope in my school. so this guy has to show up, so here it is, think i will not see "him" very frequently from time to time now, so take this chance and let me introduce you... my old buddy... before my rigol. while setting it up, i still cannot get it right, esp the reading (horizontal and vertical). still confusing as hell even after 1++ year happy with rigol. if you have seen this species, pls leave your comment.

author: dimlow
author_rank: Frequent Contributor
timestamp: April 04, 2011, 05:48:57 am
content: Hey, there is more than one button on the rigol you know

author: saturation
author_rank: Super Contributor
timestamp: April 04, 2011, 11:56:33 am
content: Nice old design [ but relatively new make of GW?] analog scope. I had a similar looking one back in the 1980s!! By Trio-Kenwood. 5 MHz, I worked it to death; it died 2 years ago and I wonder whether I should repair it or trash it; I went looking for a scope, found Dave's review, found Rigol, and the rest is history.

author: Mechatrommer
author_rank: Super Contributor
timestamp: April 04, 2011, 03:32:52 pm
content: Quote from: dimlow on April 04, 2011, 05:48:57 amthis chap got extra. vert var and swp var. the most bugging mystery for me until now. after having rigol, i started to learn what is ac/dc/gnd/int/ext pretty much everything i learnt backwardCAL is not operational anymore, dont know if its broken or is just me dont know how to use it, it just a single metal, no ground like rigol has. even the trigger (pull slope?) is delusive back during the old day. i only can confirm/understand two button very well, ie volt/div and time/div. but with previous mentioned knobs/buttons, i pretty much like tried to tinker everything without having a clue to get the phosphor moving in the scope monitor.Quote from: saturation on April 04, 2011, 11:56:33 amthis is 20MHz scope IIRC from the manual. last time i searched the closest brand is GW Instek. but operating it, make me highly doubtfull. i think this is GW'nese no brand name cro. this thing is still working as can be seen in the picture, but bid farewell to this buddy.

author: dimlow
author_rank: Frequent Contributor
timestamp: April 04, 2011, 03:46:23 pm
content: Im guessing pull slope is for falling edge trigger. The vars, i have no idea. I never had an analogue scope!!! well I did when I was about 11, but back then I didnt know what it was for. All the other controls I would have thought are pretty basic.

author: tekfan
author_rank: Frequent Contributor
timestamp: April 04, 2011, 04:42:07 pm
content: The var - variable controls give you an infinitely variable vertical gain or horizontal time base setting. Analog scopes usually have 1-2-5 steps. So 50mV, 100mV, 200mV, 500mV, 1v, 2V, 5V and so on. The variable control allows you to go from let's say 2V/div to 1.5V/div. You won't know the exact value when the variable control is enabled but it's pretty useful when comapring signals. So let's say we have a known good circuit and you're comparing it with a faulty one. You want to see if the signal in the working one matches the faulty one so you set the variable control so that you have exactly let's say 6 divisions of deflection. Then you probe the faulty circuit and if you don't get the same value you know you've got a problem.I hope I haven't confused you even moreThe variable control is also really useful for making rise time measurments on an analog scope.

author: Mechatrommer
author_rank: Super Contributor
timestamp: April 04, 2011, 05:05:05 pm
content: hmm i suspect it to be like that. with the absence of CAL output, and no voltage reference, this scope is useless for exact voltage or frequency measurement i think. maybe this is why i still confused with this unit. and yes it is usefull to exact fit the graph exactly to the screen size haha, but we will never know its exact amplitude/frequency reading.edit: i just noticed the picture above tell what i meant. look at center picture and top right. center = 4div frequency and 3div peak volt, and in the top right image, 2div freq ~2.3div peak. thats the same signal i remember. just by tweaking horz var, it will squeeze the freq from 4 to 2 div, making us think the signal is twice as fast, the same to vert var, it will change the amplitude unknowingly which one is the real value.

author: tekfan
author_rank: Frequent Contributor
timestamp: April 04, 2011, 05:46:26 pm
content: I think i can see a CAL position on the variable controls. If you put the knobs in those positions, the vertical and horizontal scale should be calibrated to the vertical volts/division and horizontal time/division settings.