Velleman HPS140i miniature DSO - a thing of beauty or ugly duckling ?

[Fraser]

I have just visited my local Maplin Electronics store (UK) and spotted the new Velleman HPS140 Digital Sampling Oscilloscope that they stock. It is currently ‘on sale’ at GBP79.99, reduced from GBP129.99, until 22 March 2011.

The maplin web site page is here:

http://www.maplin.co.uk/velleman-hps140-handheld-pocket-scope-508678

Needless to say, after a short 'play' I was adequately impressed and purchased one.

The unit has a good web site dedicated to it so I shall not repeat the specs here.

Web site is here : http://www.hps140.com/

Take a look at the 'User Demo' videos whilst you are on the site.

With a palm sized case and 40MS/S spec it appears adequate for the less demanding tasks that I have in mind for it. I would rate it in the same category as pocket multimeters... an unavoidable compromise but a very useful instrument to have around in the workshop or whilst mobile. Even Dave supports the ownership of the compact pocket multimeters. I wonder what he will think of this tiny DSO ? I don't consider it to be in the 'toy DSO' catagory. It obviously can't compete with my Rigol DSO or other full size scopes...... but have you ever tried squeezing one of them into a shirt pocket  

The unit appears to be well made and has a resilient case and bright red rubber 'glove' to protect it from the knocks that life will inevitably throw at it. Inside the case there is a 800mA NiMH battery pack that uses AAA cells. These will be easy to replace when the time comes. There is very little to see when the case is opened. The PCB is easily lifted out of the case but all the electronics are hidden under a decent quality metal screening can. You can see this in the Velleman video on “battery fitting” at the above web site. I am not going to void the guarantee by opening the tin screening can just yet as I have only had the unit a day  

The HPS140 only has four buttons and the menu’s, though clear, take a bit of getting used to. The unit has several useful signal measuring functions including dBm and Watts into a range of impedances. The voltage reading is also True RMS which is nice to have. Volts peak to peak is also selectable.

I already own several HPS10’s and these are useful provided you fully understand the limitations of the design and work within them. The HPS140 is no different but in terms of portability and bandwidth, it is streets ahead of the older HPS10 and most other miniature DSO’s. For the money, I have found Velleman portable and PC based oscilloscopes to be very good and reliable.

If you fancy having such a portable little DSO at a pretty wallet friendly price you had better hurry as it's only on promotion at Maplin until 22 March 2011.


Oh and I'd suggest buyers not be persuaded to purchase Maplins scope probe when buying the HPS140. You can get the same probes cheaper on e*ay. Search this forum for 'Wittig' and you will see that you can buy four decent Wittig X1/X10 scope probes for GBP18 ! = Plenty of sprares :-)

MCS(UK) Probe Auction is here:

http://cgi.ebay.co.uk/Set-4-200Mhz-wittig-W202-scope-probes-brand-new-/120691289053?pt=UK_BOI_Electrical_Test_Measurement_Equipment_ET&hash=item1c19c2ebdd

[saturation]

Can you take actual photos of your unit in action, and compare it against your other Velleman DSOs?

I think beauty needs to take second spot to functionality, and safety.  Velleman at least designs some safety into the scopes inputs, many of the low cost ones seem like they have none.

Velleman does say explicitly it is designed for CAT II voltage use, although I don't think it has officially been listed by UL, TUV or any such safety agency for CAT II usage.  Its uses a less clear bicolor LCD, say versus the color DSO Nano, but Velleman has better and more reliable specs, more in competition with a 6MHz Uni-T handheld scope.  Velleman's reputation is a bit more established for low cost hand held DSOs, there are very few players in this field.  Velleman's DSO have been around for ~ 10 years, and they seem just be reusing their scope modules and making tiny incremental improvements.  After reading the user's manual and watching the videos, is pretty much my scope, except for some feature changes.

I own an HPS40, its my 'sacrificial' scope and one I take around, the one I'll reach for first when testing an unknown fault with potential voltages that could fry my 1052e, after my DMM says its ok.  I like the form factor of 140i better than the bigger HPS40.  Th 140i lacks USB or old style serial port connections to ease getting screen dumps of waveforms.  Nothing your cellphone or a digital camera can't handle though, particularly in macro mode ,to get details.

The HPS40 uses 5 removable batteries, NiMH or alkaline, so its more flexible with power supply and charging.  But 5 cells is a bit odd as replacement packs typically are often multiples of 2.  Its easy to make a AAA NiMH pack, but its less convenient to replace as the 40.

The 140i insulating sleeve could probably be both ergonomic and safety, the HPS40 plastic case is luckily not slippery but has no other layer of insulation.

The 140i has a smaller screen, but it has tighter pixels.  So it show the same data as the large HPS40 screen.

If I brick my 40, I'll replace it with the 140i, its cheaper, and otherwise identical. See mikes electric stuff's test newer in the thread, he found sync issues above 1 MHz.

FWIW, there is a chinese look alike, pictured left, of the Velleman HPS40, on the right. I didn't think these scopes were very popular, but I guess the design is successful enough for someone to spend effort to make a look-a-like.

[Fraser]

Hi Saturation,

When I get five minutes I will compare with my HPS10 and take some pictures. I also own the PCS100, PCS500 and UNI-T UT-81 so I will see how it compares with them as well  

I understand that auto engineers like the Velleman HPS series for working in the difficult environs of the car engine bay or interior. Velleman made a dedicated car diagnostic kit using one of the HPS10's or 40's at one time.

I concur regarding Velleman's experience and reputation in the field. They also provide excellent support if things go wrong and repairs are usually economically viable as they can be sent to the manufacturer in Belgium for repair. I have looked at the HPS140's rear label and it states IEC1010 600V CATII but no approval symbols are present. Th emax input before damage oon the BNC is stated as only 100V peak so care muct be taken to use the correct switch setting if using a X1/X10 probe to measure higher than this level.

I was disappointed that Velleman didn't include a USB or serial link but I suppose it is built down to a cost and that was considered a luxury item that was not essential. I am pleased with the included measuring functions though. It is also worth noting that it has a standard BNC input and 1MOhm impedance, unlike some miniature scopes that have really odd connectors and scope probes that match an odd ball impedance that bears no resemblance to industry standards.

Finaly, I should say my message title was a bit of a joke rather than me seriously considering whether the unit looked beautiful or not ..... beautiful engineering and ergonomics, now that is important to me    My Ugly duckling comment is really aimed at whether this unit is judged good or bad... just my odd sense of humour  

[NiHaoMike]

It looks like a very nice unit for working on the primary side of power supplies. 10MHz bandwidth should be enough for most transformer-coupled switching supplies. On the other hand, 40MHz sample rate is fairly easy to DIY. Also note that the probe is not included.

[Alex]

Thanks for the pointer Aurora, spec wise it looks like a great unit. It certainly covers many of the applications of the Fluke 120 series at a fraction of the price. Not sure about safety though, I see this being used with mains a lot but I could not see any major components from the battery installation video.
Elektor had done a review of scopemeters a while ago covering the older Velleman unit too.

Time to take it apart? 

[Fraser]

I personaly would not use the HSP140 on high energy or mains circuits. As I indicated, I see it more in the realm of the pocket multimeter and as such would use it on low energy circuits with voltages below 100V. The unit relies upon the probes attenuator to protect it from damage above 100V and that is a situation with which I am not that comfortable.

Also note that on the label the unit warns users of the following:

"BNC and DC input are not galvanic isolated"

The BNC connector is also a metal shell type and not the safer plastic insulated type used on Flukes and even the Velleman PCS500. When a fully insulated probe is used (with plastic BNC shell), there is still an area of the BNC socket shell exposed with a potential shock hazard resulting.

As I indicated. This unit appears great, if you use it within the constraints of it's design and specification.

With regard to making a 40MHz DSO, I agree that this can be done but the neat case etc is always a challenge for me. In my world, time is money so it would not make economic sense for me to build a DSO such as this when it is available at a resonable price from a high street shop 

As to taking it apart.... well I already did that and there is nothing to see, apart from a regulator and inductor, the electronics reside inside a closed metal shield, and until I know the unit is reliable, the metal shield stays in place  

I will be asking Velleman to provide the HPS140 service manual as they made the HPS10 and 40 service manuals available via their support forum without fuss. Velleman tend to rely upon the copyright and hardware protection of their main processor chips rather than making a secret of the schematic diagram.

[mikeselectricstuff]

A 4-button UI on a scope sounds like a complete nightmare to me....
£129 is too much for a toy scope - the cheapest Owon is 10x the scope for less than twice this price.
at £79, it maybe worth it for fun though.

[Fraser]

I don't disagree that the 4 button UI is a challenge at first but the menu design is quite good so you soon get used to it. I feel it should be remembered that this DSO is designed to be ultra compact and not a bench scope killer   As I stated, it should be considered similar to the pocket multimeters in that it is easy to have in your tool bag or even shirt pocket. This would not be my choice as my one and only scope but as I am fortunate enough to have several analogue and digital scopes in different formats, this is just a product that fills a small gap in my inventory   I do think that Velleman could have had a few more buttons on the UI without over cluttering the front panel though. A scroll wheel or joystick, as found on many mobile phones, would have been another possibility. Cost may have been a factor.

You are right to highlight that a very reasonable bench DSO can be purchased relatively cheaply these days. My Rigol DS1052E continues to impress me when I consider what I paid for it. For the hobbyist who is in the market for a general purpose DSO, I would not recommend any of the portable or PC based offerings. A decent bench DSO is an invaluable tool that does not have the compromises of the portable scopes or reliance on a PC. Before anyone mentions the top end portable scope offerings from the likes of Fluke, I own an elderly Fluke PM97 and find it very good, but the price tags tend to place them out of reach for the average hobbyist.

Dave’s comments on a cheap analogue oscilloscope are also to be bourn in mind. They are so cheap on the used market these days that the hobbyist can get a decent bandwidth for a relatively small outlay of cash.

The HPS140 has one significant key feature for me….. Portability, Portability, Portability  
 

[Zero999]

Looks like good value for money.

I agree it's probably not a good idea for mains usage but most uses for a 'scope are on ELV anyway. I think I'll get just for the RMS measurement as buying a DVM which will work up to 10MHz is pricey. I hope there's still some in my local store.

[TheWelly888]

Does the HPS140i DSO drain batteries in the same way as the HPS10 when switched off and how easy is it to access the battery compartment?

Just out of curiousity as I own a HPS10 and my only beef with it is that I need to remove the batteries when I'm not using mine and one needs to use a screwdriver.

[saturation]

Here's an example from an older eevblog post I made, of the HPS40 in action.  I was troubleshooting a 300Vdc SMPS, and was surprised to see transients of 1000Vpp, but ~500V was above zero, that gives the net input exposure of 50Vdc after probe step down of 10:1.  A Velleman screen dump.  I wouldn't cry so much losing the Velleman  but it took the exposure well, but I'd be hard-pressed to examine such circuits with 1052e or better scope.

Those transients did not show up probing with a FLuke 87V, but it did suspect it, I could not stabilize the readout, and peak-hold gave unbelievable values, which turned out to be close to true.

[saturation]

Hi Aurora,

Reading on your electronic analysis in all these posts and your gear, you are the right person to do the best revue of these scopes!  You can make great comparisons, I'd like to see first is Velleman vs Uni-T 81  , since Velleman DSO models are variations on their similar electronics.

Many auto forums describe the HPS10 and it has a good following; its earned its reputation in the field, so regardless of its written specs its been proven practically.  FWIW waveforms in autos are all under 100kHz, typically in the audio range.  The competitive scopes for autos, with specs like a DSO Nano, are in the 5-15x the Velleman's costs, that's how it gained popularity.  Auto dealership service centers are forced to buy name brand gear for liability purposes, while smaller shops and personal users can buy what they feel is useful.  I have several old posts about these on eevblog.

I agree fully with your safety concerns, using the scope probe as the first line of safety puts a lot on the probe, also the BNC jack is not insulated type.  Luckily for low frequency with high voltage, like mains voltage, the probe is in spec, but one has be aware at high frequencies, voltage limits have to be derated.

Hi Saturation,

When I get five minutes I will compare with my HPS10 and take some pictures. I also own the PCS100, PCS500 and UNI-T UT-81 so I will see how it compares with tem as well  

I understand that auto engineers like the Velleman HPS series for working in the difficult environs of the car engine bay or interior. Velleman made a dedicated car diagnostic kit using one of the HPS10's or 40's at one time.

I concur regarding Velleman's experience and reputation in the field. They also provide excellent support if things go wrong and repairs are usually economically viable as they can be sent to the manufacturer in Belgium for repair. I have looked at the HPS140's rear label and it states IEC1010 600V CATII but no approval symbols are present. Th emax input before damage oon the BNC is stated as only 100V peak so care muct be taken to use the correct switch setting if using a X1/X10 probe to measure higher than this level.

I was disappointed that Velleman didn't include a USB or serial link but I suppose it is built down to a cost and that was considered a luxury item that was not essential. I am pleased with the included measuring functions though. It is also worth noting that it has a standard BNC input and 1MOhm impedance, unlike some miniature scopes that have really odd connectors and scope probes that match an odd ball impedance that bears no resemblance to industry standards.

Finaly, I should say my message title was a bit of a joke rather than me seriously considering whether the unit looked beautiful or not ..... beautiful engineering and ergonomics, now that is important to me    My Ugly duckling comment is really aimed at whether this unit is judged good or bad... just my odd sense of humour  

[saturation]

You can check the quiescent drain current easily with an ammeter.  I read those complaints too, so I checked.  I use eneloop LSD NiMH batteries exclusively now, and now you can exclude the battery self discharge rate.  I set of AA last me > 3 months.

0.5mA when off, 160 mA ON, so it will run for about 12 hours on 2000mAH NIMH rechargable batteries, 4000 hours standby, that's ~ 5 months. 

Does the HPS140i DSO drain batteries in the same way as the HPS10 when switched off and how easy is it to access the battery compartment?

Just out of curiousity as I own a HPS10 and my only beef with it is that I need to remove the batteries when I'm not using mine and one needs to use a screwdriver.

[Fraser]

Saturation,

Regarding reviews.....

I don't have a great deal of spare time these days but I would be happy to test and report on the behavior of my various scopes as time permits.

Tell me what tests you would like and I will see what I can do over the coming weeks/months. I have a well equipped home RF lab with signal generators that are good to 1.2GHz but my Function generators and pulse generators are more humble. The fastest pulse generator that I own is an EH G710, rated at 50Mhz/ less than 5nS 10%-90% rise time.

As I have said, I am very limited in the amount of time I have to ‘play’ so best endeavors will apply.

[Fraser]

TheWelly888 ,

Battery drain when off?

Sorry, only bought it yesterday so not tested yet.

The battery is easily accessed for replacement by the removal of the four case screws and the unplugging of the battery connector. The battery is a 3 AAA cell 800mA NiMh pack with a stated run time of 6 hours. No spec is given for self discharge times.

[saturation]

Hello Aurora,

Yes, I understand, time is short for everyone.  At the least, just the highest frequency response of the Uni-T 81 versus your HPS140i.  A square wave at 100kHZ for a the baseline, then 1MHz, which reflect on the 5th - 9th [at most], so the appearance will be an indication of its response to 5MHz - 9 MHz, the upper limit of their capability.

If you still have time, using a fast pulse generator, determine the rise time of each.

That's pretty much it.  Ergonomics are not that essential.

I saw an initial post will all your scopes!  Impressive, I think you've edited it away.  I think the Uni-T and the Velleman are the only true contenders in the low end DSO group.  All the others, Fluke, Protek, Owon etc., are in a different class altogether.

Saturation,

Regarding reviews.....

I don't have a great deal of spare time these days but I would be happy to test and report on the behavior of my various scopes as time permits.

Tell me what tests you would like and I will see what I can do over the coming weeks/months. I have a well equipped home RF lab with signal generators that are good to 1.2GHz but my Function generators and pulse generators are more humble. The fastest pulse generator that I own is an EH G710, rated at 50Mhz/ less than 5nS 10%-90% rise time.

As I have said, I am very limited in the amount of time I have to ‘play’ so best endeavors will apply.

[Fraser]

Hi Saturation,

I will see what I can sort out this week for you. No problem with generating decent square waves at the specified frequencies and I can always try some analogue sine wave tests at the stated max freq to see what happens.

Yes, you are right.... I removed the list as it didn't sit well with me when I read it back. I don't think people want to know how many scopes I have    It looked like bragging to my eyes and that was not the intention

[TheWelly888]

You can check the quiescent drain current easily with an ammeter.  I read those complaints too, so I checked.  I use eneloop LSD NiMH batteries exclusively now, and now you can exclude the battery self discharge rate.  I set of AA last me > 3 months.

0.5mA when off, 160 mA ON, so it will run for about 12 hours on 2000mAH NIMH rechargable batteries, 4000 hours standby, that's ~ 5 months. 

Thanks for the data, saturation, but I use my HPS10 much less often than every 3 - 5 months! What I have done to get round the standby drain current is to put a small piece of plasticard ( eg from expired credit card ) between an end battery and the terminal when I'm not using it. It is also annoying that the HPS10 uses 5 x AA batteries when one gets them in packs of 2, 4 or 8!

Anyway I like the HPS10 because you effectively have a floating input DSO when it's running off batteries only -
I only wish I got the HPS40 for the LCD backlighting!

[Fraser]

Thewelly888,

Please be aware that the HPS140 comes fitted with a NiMh rechargeable battery as standard and so whilst this will save you buying batteries for it, you will not be able to quickly isolate the battery, and even if you did, the internal self dicharge rate of the Ni-Mh cells would mean they were pretty much discharged after a few months and would need recharging.

The HPS140 also has the backlight supplied as standard. Why this was not the case with the HPS10 I will never understand. I fitted a backlit LCD panel to one of my HPS10's and it works well. The LCD is an industry standard product with 128x64 pixels and a KS0107 controller on board. Mine cost $20 delivered to the UK from China. It is a bit too thick to fit behind the front plastic but as a smashed front plastic and LCD was the reason for my replacement LCD purchase this didn't matter to me. You will likely wish to source a slightly thinner display unit. I attach the PDF datasheet for my backlit LCD for your info.

[mikeselectricstuff]

My 'new toy' impulse got the better of me & I just picked one up. First impressions are quite good - screen update is very responsive and it's a nice size and feel, unlike the old Velleman unit I had a few years ago, which was just horrible.

The 4-button UI seems to have had some thought put into it, but they could easily have added a couple more buttons.

It will get taken apart tonight when I get home & that shield will be coming off...
 
A few initial things -
The charge lead is a USB DC/DC converter housed in a 'lumpy' USB plug, putting out 9V to a mini power jack. They should have put a USB mini or micro on there and an internal converter, to charge with a standard cable.

It slightly defeats the point of having a very compact unit if you need to take an equivalent volume of leads etc with you.  For a similar reason, it would have been nice to have a small probe included, with some neat way of it being stored in/on the case. Good that it uses a standard BNC though,

There is a note in the manual saying "Do not operate the device when charging from USB", which is a bit doddy, presumably due to total power draw - if it was a problem it really should auto-disable rather than relying on a note in the manual that people won't read.

The case feels quite nice - there's no tilt stand, but display contrast is wide enough that it's pretty useable flat on its back.  It does need the rubber condom case though - the plastic is quite thin and does feel a bit flimsy when 'naked'.

 It would also have allowed for a USB data link which would have been nice if only to have the option of updating firmware (There is an internal ICSP header but I can't see them releasing updates that you need a programmer for...).

It has a 'hard' on/off slide switch, so draw when off shouldn't be an issue, although as far as I can see it doesn't have auto powerdown.

Another minor annoyance - it doesn't remember the probe x1/x10 setting after a powerdown.

More later...

[NiHaoMike]

There is a note in the manual saying "Do not operate the device when charging from USB", which is a bit doddy, presumably due to total power draw - if it was a problem it really should auto-disable rather than relying on a note in the manual that people won't read.

That's probably a ground loop or noise problem.

[Zero999]

No it's because they can't guarantee the isolation/withstand voltage of the source used to charge the 'scope. Suppose you charge the 'scope from your laptop then decide to measure the mains with the 'scope? You could fry the laptop or be fried if you touch the laptop.

For them to enable you to use the 'scope whilst it's being charged, they'd need to include an isolated DC-DC converter which would drive up the cost too much.

[Fraser]

 Some additional comments from me to balance my positive views of the product…..

I must agree regarding the odd USB charger but I actually prefer to charge the unit from a regulated plugpack anyway so no great problem and I have regulated 9V car chargers as well.

Regarding charging, my unit seemed to get a tad warm and smelled like hot electronics when charged off of the supplied USB charger. A check revealed that the USB charger outputs 9.91V (10% high). Velleman advised me that this was OK,"the electronics would just get a little hotter"   On a 9V regulated plug pack it runs cooler and there is not the 'hot' electronics smell that was caused by the USB charger. Velleman failed to advise me of the acceptable charging voltage range.

I believe the comment regarding using the scope whilst charging from a USB port MAY be due to the lack of galvanic isolation between BNC and charging port so a computer USB port could be exposed to damaging voltages. Current load on the USB upconverter is also a possible issue as Velleman state 500mA USB input current draw for an upconverted 9V 200mA capability.

It is a pity that the charge LED remains lit whenever a charger is connected. The led does not extinguish when charging is completed. Charging the 800mAh battery takes 7 to 8 hours. The battery pack area of the case becomes warm after around 7 hours indicating that the cells have reached near full charge.

I have to agree that the availability of a nice compact probe would have been great.

I purchased a small digital camera case for my HPS140 and it fits like a glove. The probes and USB charger will have to go in a 'probe bag' like those that Fluke use.  Another type of camera case may provide enough room for a standard probe to be stored.

Velleman politely declined my request for the schematic or service manual, stating that the product was too new to market for the technical information to be released into the public domain. They did not say it would never be released, just not at the moment.

My colleagues at work all agree that the HPS140 is a very neat and compact design providing better capability than any similar sized device presently on the market. A good compromise solution to the challenge of  carrying an oscilloscope ‘just in case’ without it becoming a nuisance. A bit like the SLR verses the Compact digital camera really. The display is very clear with good, even backlighting but the four button keypad remains my only negative user experience really. I feel sure I will get used to it though.

[Fraser]

I've just had my first use of the HPS140 in a real world situation......

My neighbour came round with a CCTV Bullet camera and said he wasn't getting a picture on his CCTV.....would I check it out for him. I quickly plugged it into a 12V plugpack PSU and connected the HPS140 to it's BNC 'video out' connector.

The result.... the BNC output went from a flat line 0V with camera power off, to +60mV DC offset with +-10mV noise with power on !

It's safe to say the camera electronics received the 12V but the BNC tells the story.... it's stuffed   These cameras are basically disposable and not worth repair time. I have it for a post-mortem if I find the time.

The whole test took less than the time taken to grab a 12V plugpack and connect the HPS140 to the Camera output. I know I could have plugged the camera into a CCTV monitor but then I wouldn't have seen the subtle dc level that came out of the BNC connector so it could have been a broken supply cable or dead input protection fuse.

At least my neighbour knows it's dead and not another problem in his system. I checked his installation to make sure his PSU hadn't killed the camera. The HPS140 came into play again..... reading a DC voltage of 12.2V with only 1mV of ripple on it. Good enough for a camera. I fitted a new camera as a temporary measure and quickly set up the levels on it. Once again the HPS140 provided invaluable information regarding the CCIR signal. All was well in the end, with correct amplitude and sync pulse levels.

It makes such a difference to have a fully functional oscilloscope literally in the palm of your hand  

[Fraser]

Almost forgot.....

Whilst using the HPS140 you can hear reed relays operating inside it as it changes ranges. I had assumed that it would use some form of electronic switching or an instrumentation amplifier IC with gain control, fed from a fixed attenuator stage like many USB scopes. I must say I like the idea of a relay switched attenuator if that is what I am hearing.