RPS2050 pen style scope review & teardown  - Page 1
Forum section: electronics / general

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: June 05, 2012, 10:09:26 am
content: Supplier links :http://www.diyertool.com/measuring-equipment/oscilloscopes/rps2k-series-pen-type-digital-oscilloscope-rps2050.htmlhttp://www.diyertool.com/measuring-equipment/oscilloscopes/rps2k-series-pen-type-digital-oscilloscope-rps2025.htmlhttp://www.diyertool.com/measuring-equipment/oscilloscopes/rps2k-series-pen-type-digital-oscilloscope-rps2010.htmlhttp://www.diyertool.com/measuring-equipment/oscilloscopes/rps2k-series-pen-type-digital-oscilloscope-rps2005.htmlhttp://www.diyertool.com/measuring-equipment/oscilloscopes/rps2k-series-pen-type-digital-oscilloscope-sp40.html

author: gtsili
author_rank: Contributor
timestamp: June 05, 2012, 10:41:33 am
content: 160 quid down the drainWe got a teardown video but, I am really sorry for you Mike

author: EEVblog
author_rank: Unknown
timestamp: June 05, 2012, 10:52:33 am
content: The ADC is a rebadged or ripoff AD9288 perhaps?Dave.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: June 05, 2012, 10:59:26 am
content: Quote from: EEVblog on June 05, 2012, 10:52:33 amDoes look somewhat similar.... even the graphics in the datasheet are clearly lifted from AD... Funny how identical the datasheet performance graphs are..,!http://www.csmsc.com/info/chinese/adda/HWD9288.pdfhttp://www.analog.com/en/analog-to-digital-converters/ad-converters/ad9288/products/product.html

author: EEVblog
author_rank: Unknown
timestamp: June 05, 2012, 11:05:04 am
content: Quote from: mikeselectricstuff on June 05, 2012, 10:59:26 am*snort*Dave.

author: Bored@Work
author_rank: Super Contributor
timestamp: June 05, 2012, 11:21:44 am
content: If you go to the manufacturer's websitehttp://www.realt.cnyou are pestered with an invitation for a live chat after looking at some products. Maybe an opportunity to provide the manufacturer with some feedbackAnd here is the original 14 pages manualhttp://realt.cn/images/load/RPS%E7%A4%BA%E6%B3%A2%E7%AC%94%E7%94%A8%E6%88%B7%E6%89%8B%E5%86%8C.pdfGoogle translate doesn't work too great, but some mysteries can be decoded with a side-by side comparison of original and translation. E.g page eight says the blop on left of the display is the trigger status. And the strange heart shaped icon is supposed to be a USB plug and should show USB connection status.http://translate.google.com/translate?sl=auto&tl=en&js=n&prev=_t&hl=en&ie=UTF-8&layout=2&eotf=1&u=http%3A%2F%2Frealt.cn%2Fimages%2Fload%2FRPS%25E7%25A4%25BA%25E6%25B3%25A2%25E7%25AC%2594%25E7%2594%25A8%25E6%2588%25B7%25E6%2589%258B%25E5%2586%258C.pdfThere is also some mentioning of test signals the thing is capable of generating.

author: Lightages
author_rank: Unknown
timestamp: June 07, 2012, 03:48:23 am
content: First off Mike, sorry for even seeing this thing in DX. I had no idea it could be sooooooo bad. By buying this hunk of shit you have saved me the trouble and money down the drain, I have the Wittig Oszifox Penscope, actually two of them. For the $30USD I paid for each, they look like 1000x better value for the money, even from 90s technology!You took a bullet for me so to speak, I guess my wallet is on the line the net time I see something "interesting".

author: A Hellene
author_rank: Frequent Contributor
timestamp: June 07, 2012, 11:10:44 am
content: I can feel your pain, Mike...Anyway, thank you for the teardown of that pen-scope, which strongly reminded me of theRadioShack ProbeScopeI had purchased in the late nineties for USD ~80, if I remember correctly. The ProbeScope was a 20Msps device, with 50ns..1.0ms timebase and 1V/10V/100V AC/DC input range, pen-scope/voltmeter that run on a 12V/20..100mA external power supply (its PCB run on 5.0V). Its accuracy was laughable, but it was very useful for the reverse engineering of PCBs, I used it for.This is the ProbeScope PCB:ProbeScope v4.1 (PCB v6.2, 32nd week of 1996)At the top left of the picture can be seen my botch-work of adding a switchable 9.0 Mohm (= 4.7M + 4.3M) input resistor with a couple of AC compensating capacitors that form a 10:1 resistive/capacitive divider with the 1.0 Mohm device input, in order to expand the 100Vpp max. input range and to become able of using ProbeScope to troubleshoot the CDI/TCI motorcycle ignition controllers I used to repair and upgrade by that time.As expected, of course, I managed to kill the device by accidentally touching a 300VDC output line of a CDI DC/DC converter while I was probing the low voltage section of the PCB, with the 9.0 Mohm front-end bypassed...-George

author: Lightages
author_rank: Unknown
timestamp: June 07, 2012, 02:46:46 pm
content: That is the same as the Wittig Penscope. Mine is actually the Radioshack branded one too. Yes the accuracy was far from good but it still is a better buy than the unfortunate pile of crap in this review.

author: A Hellene
author_rank: Frequent Contributor
timestamp: June 07, 2012, 03:47:47 pm
content: Yes, I saw that; after posting my message above, I searched for information about the Oszifox Penscope.Of course, I bought mine not for $30 but for $80 in '97; and I am too lazy now to find out the '97 rates and adjust the price in today's currency value... If I remember correctly, it was designed by some German firm and was branded and sold by Tandy/RadioShack. Does the PCB of yours have the same chips and markings?-George

author: ju1ce
author_rank: Regular Contributor
timestamp: June 07, 2012, 06:11:52 pm
content: Thanks for the video Mike.

author: Lightages
author_rank: Unknown
timestamp: June 08, 2012, 02:43:44 am
content: A Hellene:I will be posting another thread to not hijack Mike's

author: nukie
author_rank: Frequent Contributor
timestamp: June 08, 2012, 04:46:41 am
content: Motorola engineers.

author: free_electron
author_rank: Super Contributor
timestamp: June 08, 2012, 06:34:23 am
content: Wittig is still around... they seem to come and go... sell rebranded scopes.

author: Bored@Work
author_rank: Super Contributor
timestamp: June 08, 2012, 07:23:16 am
content: Wittig went bancrupt around 2006 or 2007. At that time the W2000 or W2000A oscilloscope firmware source code made it to the community and became the start of a community project to fix/rewrite it.The Wittig family/brothers opened a new company, Welec, and kept selling W2000A oscilloscopes. Whether that was NOS they took over from Wittig, or a new production run is anyones guess. Welec hasn't come up with anything new since they started in 2007, just selling the old Wittig W2000As.

author: Bonati
author_rank: Newbie
timestamp: June 08, 2012, 01:47:02 pm
content: (first post, hi everyone)Thanks Mike, love your videos. Stay angry! Would love a video tour of your shop sometime if you're ever up for it.

author: free_electron
author_rank: Super Contributor
timestamp: June 08, 2012, 03:17:16 pm
content: Like i said.. They come and go ... Go bankrupt, come back under different name, disappear again, come back again..The ws2000 does have a real vga screen 640*480 as opposed to qvga 320 240

author: billclay
author_rank: Regular Contributor
timestamp: June 11, 2012, 05:11:02 am
content: Mike, your review was great! Not owning one of these, how do you easily view the display while probing? You probe straight down (or at a slight offset) and you have to twist your head at a strange angle to read the display? Doesn't sound fun if the space you are working in is tight, after all you said it is suited for field work.Oh, and BEEP, BEEP, BEEP, BEEP, BEEP, BEEP, BEEP, BEEP, BEEP!

author: Hypernova
author_rank: Unknown
timestamp: June 11, 2012, 06:37:46 am
content: The OLED used appears to be the Crystalfontz CFAL12864N-A-B4 (http://www.crystalfontz.com/product/CFAL12864NAB4)I wonder if they got the ATmega8 there just to handle the scroll wheel and stuff, it's in a pretty bad position though since having it there before the ADC would probably introduce some noise and may be the reason the readings look a bit wobbly sometimes. Pretty silly design at the system level, there is no reason why they need to have more than one MCU in the whole thing, it may even be possible to embedded that into the FPGA as a softcore.

author: steve_w
author_rank: Regular Contributor
timestamp: June 11, 2012, 06:42:37 am
content: Mike,Good review, keep up the good work.regardsSW

author: T4P
author_rank: Super Contributor
timestamp: June 11, 2012, 07:10:05 am
content: Quote from: Hypernova on June 11, 2012, 06:37:46 amIt's even more stupid to pack it into that tiny oled display, the oled display would be better used for other things

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: June 11, 2012, 07:59:15 am
content: Quote from: billclay on June 11, 2012, 05:11:02 amI don't think display readability is a problem - unless you're in a deep, tight space you can easily see the display. One thing that would improve it would be to have the display nearer the tip.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: June 11, 2012, 08:00:57 am
content: Quote from: DaveXRQ link=topic=8762.msg119758#msg119758It's even more stupid to pack it into that tiny oled display, the oled display would be better used for other things[/quote

author: amyk
author_rank: Super Contributor
timestamp: June 11, 2012, 08:18:46 am
content: They probably chose the display size because it's averycommon size in MP3 players and so available for really cheap.As for the 2 controllers, my guess is they designed one part with the FPGA and ADC controlled by one, and another team designed the other part with the UI and used another to control that. Given the state of the firmware, they're probably not skilled enough to integrate everything into one FPGA; many Chinese companies are like this, they know how to connect parts together but are awful at writing the firmware for them.Making a sound with every UI action is another one of those things I've seen a lot in other consumer electronics like phones and cameras. Maybe Chinese factories and electronics labs are loud places, but at least they could have an option to disable it...

author: saturation
author_rank: Super Contributor
timestamp: June 19, 2012, 07:16:41 pm
content: Thanks, Mike, enjoyed it quite a bit. As you say, it had great potential as a hand held quick check scope in the $200 range were there are still few in the market [ Uni-T UT81D and the Vellemans, AFAIK.] But, it does look like it needs more work.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: June 22, 2012, 11:04:47 pm
content: Mods to add proper on/off switch and kill the beep :