Well, My cheap Chinese knock off hand held scope meter has all isolated inputs for the common. I own 2 of these scopes. one is 20 mhz and the other 60 mhz My bench unit is 350Mhz but that's an TEK analog which I still like using. the Digital's are for quick and dirty stuff.
I do get to use a 200 mhz digital at work.
-- "I\'m never wrong, once i thought i was, but was mistaken" Real Programmers Do things like this. http://webpages.charter.net/jamie_5
So if you have a scope without the true floating inputs, how do you measure a high side switching fet in that case?
cheers, Jamie
Last time I had to do that, I unplugged the HV and clipped the probe to the gate drive's output. ;-)
It's kinda funny that a few DC volts are developed on the bridge, due to gate capacitance and rectification.
Tim
-- Deep Fryer: A very philosophical monk. Website @
New kid on the block; almost no reliability data. I say, tread carefully.
A scope that I can't shake too hard.. :)
I think I can get 2 new Rigols (100Mhz 2ch) DSO's for the price of 1 new Tektronics DSO (100Mhz 2ch) with nearly the same specs. (Needs verifying.)
With 2 Rigol scopes... When one Rigol scope breaks...I can use the other Rigol scope to test it or scrap it for parts.. :) Heck... Maybe 2 Rigols might last as long as one similar Tektronics. Rigol disposible scopes.. :P Perhaps by the time the Rigol breaks..I'll have saved up enough money to get the next generation lastest/greatest test equipment. (I'm so glad my CRT computer monitors broke..)
However.. I'm considering the Instek GDS-2204 200Mhz, 4 channel, 1Gs/s, 23kpoint mem. Stocked in California I think. Made in Taiwan.
And I'm trying to work a $500 cash deal locally for a Tektronics 2465B
400Mhz 4ch analog scope. (I think I saw somewhere they used to go for $16000??)D from BC
On a sunny day (Mon, 08 Oct 2007 03:33:30 GMT) it happened Jamie Morken wrote in :>
You could use 2 channels, substract, use 10x probe. That will give you a bit common of mode range, and could work if your signal is big enough.
The real killer is a FET probe plus the 2x20dB HP amplifier. "Eeew, I never thought that kind of noise was riding on this rail ..."
I got both of mone used. One Tek and one Philips. I wish the cable was less bulky. Over the years I have repaired many, typically a few cheap SOT23 devices do the trick. I could imagine there should be some deals at EBay under the "not tested, as is" category just like with the stash of sample heads you've bought.
Because of the bulk and hassle I often use a resistive divider on a 50 ohm coax instead. Above 100MHz or so there is rarely a need for impedances higher than a kiloohm.
-- Regards, Joerg http://www.analogconsultants.com
23kpoints memory is too small. Go for at least 1Mpoints. Besides, if you want to measure anything over 100MHz, you'll need special probes too that use the 50 Ohm inputs of your scope. Either FET or passive dividers.
-- Reply to nico@nctdevpuntnl (punt=.) Bedrijven en winkels vindt U op www.adresboekje.nl
Better plan on "plan B" :-)
-- Regards, Joerg (a guy who does a lot of switchers) http://www.analogconsultants.com
No, they didn't. They stole a $300+ dual channel triggered scope with less than 100 hours of use that I had to replace out of my own pocket.
Microdyne had almost 100 Leader LBO-508 scopes, and most were in use, daily in both engineering, and the test line. They were over 20 years old, and still in good working order. When needed, better scopes were available, both analog and digital. I had a Tek 2465 on my bench, for several years.
-- Service to my country? Been there, Done that, and I\'ve got my DD214 to prove it. Member of DAV #85. Michael A. Terrell Central Florida
I think "Plan 9 from Outer Space" would be more appropriate!
-- Service to my country? Been there, Done that, and I\'ve got my DD214 to prove it. Member of DAV #85. Michael A. Terrell Central Florida
Jan Panteltje snipped-for-privacy@yahoo.com posted to sci.electronics.design:
Say what you will, good attenuators from DC to 100 MHz are not all that difficult. DC to 1GHz are more difficult. DC to 10 GHz are really challenging (and beyond me).
If you don't believe me try it. Personally, i would rather beg, buy, "borrow", or salvage one.
It's a "I wanna..I wannna" new toy type of thing with me and DSO's.
Getting an old dusty 400Mhz Tek2465B is just ..yawnnn ... nothing new..just a tool.. Wellll... the DSO will become just a tool (or bench decoration) once I start saying "wtf! That's a bullshit rise time!"
I recall trying a DSO in 1998.. I looked for the games button :) You know..maybe space invaders or pong on the scope :P Nowadays... I have to wonder if I can get new ringtones off the internet for a DSO :)
But seriously.. Jumping to plan B sounds good.. Analog scope for smps design. :) Thanks
I'll get a DSO when a project pops up that's best with one. No pretty colour waveforms or digital flare and glitter today :(...
D from BC
You might be interested in the Rigol DS1202CA, 200MHz, 2GS/s real- time, 2ch, color with 10k of memory (single channel or 5+5k 2ch.).
They are just new to the market and remarkably similar to the Agilent
5000 series scopes. I took one along to a calibration lab today to get an unbiased opinion and was plesantly suprised with the results. The 200MHz bandwidth was actually 224MHz in real-time sampling (2GS/s) and 379MHz in equivelent sampling (25GS/s). The frequency counter and from that the timebase was accurate within 0.00001% and the voltage less than 2%. The manual was well written with no hint of "chinglish" and it was the first digital oscilloscope they had ever seen that had an option to change skins! The only thing they could fault with it was when displaying an AM modulated waveform the gridlines were at the back of the trace and there was no option to overlay the grid on top of the solid waveform. I will send the feedback to the factory though and I'm sure that will just be a firmware upgrade.You should be able to pick one of these up for the same or less than the Tek TDS2022B and from what I saw today you'd get a much better instrument.
Duncan
clear.
You can sometimes get older TDS scopes cheap off EBay. Once I was tempted. Sad actually, a woman was selling it because her dad had passed away. But I didn't bid because I got burned too many times by the switcher noise out of these scopes. The deal was good though except that the old TDS scopes didn't not have good connectivity. But for digital work where you just need to diagnose a problem they are good.
-- Regards, Joerg http://www.analogconsultants.com
clear.
Have you ever noticed that those who deisgn switchers hate them the most? ;-) When someone tells me the size of an inductor, I say "No, that inductor is as big as a house, at least according to my AM radio." The wall wart crowd has discovered switchers, and boy do they sing.
I downloaded that Hameg catalog. Can you start another thread and explain the nuances of their scopes. [Anyone can talk specs, but there is nothing like hands on knowledge.]
I personally have a problem buying gear that isn't Tek or HP (Agilent). It is a lot like "nobody got fired for buying IBM" mentality. Now I do have Fluke and Keithley gear, but I think that is it for non HP/Tek stuff. [OT, but wavetek gear has been nothing but trouble.]
clear.
I like switchers because I design them. But it blows my gasket if I find expensive gear that shows some level of incompetence. Ok, on a $20 clock radio I won't complain but when it's lab gear which commands a princely sum I will.
I am not the right guy for that, I only own a really old Hameg, 30+ years. Have used some others though, sometimes wished they were mine. Works like on day one, has been through a lot of abuse when I was a kid. Amazing. Over at the German d.s.e. newsgroup there are lots of Hameg users but the threads there aren't in English.
I used to be the same but when HP started outsourcing designs to Yokogawa this fairyland thinking began to crumble. After the last run-in with TDS noise I have no qualms anymore whatsoever to buy from any other source. GW-Instek was the most recent and won't be the last one. I expected nice quality and they delivered nice quality. My message to the "big two" is this: Don't rest on your laurels, they wither away faster than you think. Look at Detroit for classic examples.
-- Regards, Joerg http://www.analogconsultants.com
clear.
some
If
I've used the YHP stuff. I thought it was OK. The 4195 comes to mind. I'm sure you will recall the Sony/Tek joint ventures. Two good companies merge to sell junk.
I see Instek has a presence in Chino. That's a good sign. he nice thing about HP gear is the number of people out there that can fix it.
However, the US mfgs have to become a bit trigger-happy when it comes to calling something out of support. With some stuff you'll be on your won. Recently I had to repair the old 4191 here. Works fine again and calibrated ok but it was no fun (got a back pain because it's so heavy).
-- Regards, Joerg http://www.analogconsultants.com
In the bay area, there are a few people known for HP repair. Even if you can get a service manual, much gear requires special items just to do the repair. The HP 8660C I have is a good example. There are extender cards needed if you want to probe modules while it is running. A shop in Morgan Hill has all the toys to do this, and the cost was reasonable.
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