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

[mikeselectricstuff]

Finally got my HPS140 back after about a month. Firmware version shows as build 1112
Trigger issue appears to be resolved, but still not really useable over 5MHz.

[Fraser]

Mike,

Totally agree.

What I find interesting is that the UNI-T UT81B manages to display a decent sine wave at 15MHz with a 40MS/s sampling rate yet the little HPS-140 sort of gives up trying at around 7 MHz and hits a 'brick wall' , producing total rubbish on the screen. I am assuming that this is due to a much simpler design and signal processing algorithm in the smaller unit that cannot adequately cope with the aliasing that occurs above 7 MHz. There is also the possibility that the ADC tops out at 7MHz as it is designed for video signal conversion and such signals are usually around 7MHz in bandwidth. The ADC chip datasheet claims 10MHz capability though. 

[mikeselectricstuff]

You need a good filter in front of the ADC to avoid aliasing while preserving bandwidth, i.e. a fairly sharp cutoff - the  HPS140 is obviously built to a minimum cost, and has simple filtering.
At the  5-10MHz range you will probably only get the extreme aliasing artefacts at frequencies that are close to exact fractions of the sample rate. Do you feel lucky...?
I note the box says "bandwidth up to 10MHz"..

[AheadOfTheTimes]

Here's a question on the new Velleman: how is it regarding emitting unwanted RFI?  The fact that the triggering is problematic suggests it might be noisy.  In fact I tried an expensive Fluke ScopeMeter and even running from the internal battery the emissions were blatantly bad.  An AM radio would buzz from it at a distance of about 4 feet!  I've heard the other Velleman's are better in this regard.  Anyone have an AM radio or other way to test?

[ivan747]

Here's a question on the new Velleman: how is it regarding emitting unwanted RFI?  The fact that the triggering is problematic suggests it might be noisy.  In fact I tried an expensive Fluke ScopeMeter and even running from the internal battery the emissions were blatantly bad.  An AM radio would buzz from it at a distance of about 4 feet!  I've heard the other Velleman's are better in this regard.  Anyone have an AM radio or other way to test?

I have both an AM radio and a HPS-10 scope. Tell me what you want me to do, specifically and I'll try to do the tests.

[saturation]

Hmm that's pretty awful, I don't get this with the HPS40, but its an older model and claims FCC certification [ to be free from interference].  If you could post a video about it, and let them know, they responded to posters here with a bug report, as you can read on the thread.

Here's a question on the new Velleman: how is it regarding emitting unwanted RFI?  The fact that the triggering is problematic suggests it might be noisy.  In fact I tried an expensive Fluke ScopeMeter and even running from the internal battery the emissions were blatantly bad.  An AM radio would buzz from it at a distance of about 4 feet!  I've heard the other Velleman's are better in this regard.  Anyone have an AM radio or other way to test?

[AheadOfTheTimes]

Thanks Ivan.

Most AM radios (unless they have noise suppression circuitry) will buzz if tuned between stations
and held near a broadband noise source (you probably know the AM antenna is generally a small ferrite bar inside the unit).
Just tuning to the low end of the dial is usually enough.  Try holding near a computer to see if it works.
Then see how far from the Velleman the radio will buzz.  Could be inches or a few feet.  If the radio buzzes
everywhere in the room with everything you own off, call the power company and get them to check
the overhead lines.

I have both an AM radio and a HPS-10 scope. Tell me what you want me to do, specifically and I'll try to do the tests.

[ivan747]

Thanks Ivan.

Most AM radios (unless they have noise suppression circuitry) will buzz if tuned between stations
and held near a broadband noise source (you probably know the AM antenna is generally a small ferrite bar inside the unit).
Just tuning to the low end of the dial is usually enough.  Try holding near a computer to see if it works.
Then see how far from the Velleman the radio will buzz.  Could be inches or a few feet.  If the radio buzzes
everywhere in the room with everything you own off, call the power company and get them to check
the overhead lines.

I have both an AM radio and a HPS-10 scope. Tell me what you want me to do, specifically and I'll try to do the tests.

I will perform the test tomorrow or this Saturday. It is 10:30 and I'm going to bed. 

[ivan747]

Thanks Ivan.

Most AM radios (unless they have noise suppression circuitry) will buzz if tuned between stations
and held near a broadband noise source (you probably know the AM antenna is generally a small ferrite bar inside the unit).
Just tuning to the low end of the dial is usually enough.  Try holding near a computer to see if it works.
Then see how far from the Velleman the radio will buzz.  Could be inches or a few feet.  If the radio buzzes
everywhere in the room with everything you own off, call the power company and get them to check
the overhead lines.

The oscilloscope makes the radio buzz when it is held about 10cm away from it. It is a high pitched noise, probably produced by the digital side of the scope, which is the middle part where the buttons are. The HPS-10 uses a very nice three board construction, one board is the screen, the other is the button interface board and the last one contains the analog and digital circuitry, well separated. The screen is above the analog area of the main board; the buttons are above the digital area of the main board. The lower part of the scope is occupied by the battery compartment. I have some pictures of the scope I took a while ago, if you want them, but I would probably make another thread for that.

[Fraser]

RFI at 10cm is actually a pretty good result ! Running digital electronics near a very sensitive MF receiver using the ferrite aerial, in the H field domain is a pretty tough test, as metal RF shielding is less effective against H field emissions. I do EMC/TEMPEST work and use EMC E field & H field probes to test emissions from equipment. I would expect a reputable company like Velleman to do similar before placing the infamous CE sticker on it. My HPS140 is well behaved with regard to RFI generation and I see nothing to suggest that it is any worse than any other digital electronics. Much RFI emits from the LCD panel areas of equipment as they are usually poorly screened or unscreened.

[AheadOfTheTimes]

I agree 10cm is not bad.  If anyone can compare to an older handheld Velleman I'd appreciat it.  My Agilent DMM (1252A) is quiet until a couple inches from the display (except when measuring capacitance, when it radiates from the leads).  My Tek handheld scope radiates from the outer conductors of the coax probes (with no signal). 

[ivan747]

I agree 10cm is not bad.  If anyone can compare to an older handheld Velleman I'd appreciat it.  My Agilent DMM (1252A) is quiet until a couple inches from the display (except when measuring capacitance, when it radiates from the leads).  My Tek handheld scope radiates from the outer conductors of the coax probes (with no signal).

Isn't the HPS10 the oldest model? I have the HPS10, not the HPS140i, just in case you though I have the '140.

[AheadOfTheTimes]

Oh, I had heard previously the HPS10 was good in this regard, so you've confirmed that... would love to know about the 140 or other models.  Can anyone report?

[Fraser]

Resurrecting an old thread here but it may be useful to others as Velleman are playing hard ball on the firmware upgrade.

I bought another HPS140 recently and upon switching it on it announced firmware 1041 rather than the later 'fixed' version 1112.

Before buying an HPS140, I advise the potential buyer to confirm which firmware is loaded.

I note that Velleman are not accepting this as a firmware bug on their forum, which was a great surprise to me. Further, Velleman are now stating that the 1112 firmware will be installed at the customers request for free but with ALL postage and handling charged to the customer 

Oh dear, this is not the Velleman support that I have known and loved over the years. Its bad enough to have a bug in your firmware on new equipment, but to then be told you have to pay postage to and from the factory is verging on rude and very poor support practice when an identified F/W bug is involved. It is a great pity that the HPS140 cannot be firmware flashed by the owner.

I have written to Velleman asking for a firmware upgrade at no cost to me. We will see how they respond on this occasion. I am hopeful that Velleman will take the honourable path and not charge postage and handling. If you recall, last time I sent an HPS140i to them, they were so concerned about the inconvenience and my postage costs that they repaid me in kind in the form of a free oscilloscope probe. I wonder if that good customer service is still alive and well ?

Aurora

[Fraser]

A fast response from Velleman.

"You can still return your unit for a free firmware update (shipping not incl).
Please return it to:
Velleman Projects Tech. Dept.
Legen Heirweg 33
9890 Gavere
Belgium

Make sure to include a note that says 'firmware update', so that our engineers know what to do. "

So it would appear that Velleman are yet another company that has lowered its support standards. I shall approach them again on this matter as its not really good enough. I have to say that their stance that the triggering problem isn't actually a 'Bug' in the firmware is laughable....'you can still use the DSO for low frequency work' is their opinion of the firmware situation

Aurora

[saturation]

Sorry to hear.  Maybe better to return the unit from where you purchased it from, since they have older stock.  Buy elsewhere then ask the seller if they can check the firmware version?

[Fraser]

Good news 

Vellerman made an error in their reply to me. They will cover the firmware update under warranty and without the return postage cost.

All is well again in my little world 

Aurora

[alm]

Sure, an error. We accidentally gave you the impression that we don't care about customers. It just means you can force them to do what a good company would have done in the first place if you're persistent enough. People with less experience would probably have given up and paid for shipping themselves.

[teaker1s]

Hi has this been resolved or is the UNI-T UT81 still a better bet at a similar price?

[teaker1s]

Verification deletes my message but at £89 is this a bargain or is it worth another say £50 for something else? mine is due tomorrow.

[Fraser]

A Bargain..... Hmmm ... you do get what you pay for with DSO's and there are some very nice bench DSO's available for very reasonable money these days, new or used. I picked up a lovely Tektronix TDS220 recently for £130, it is worlds apart from the Vellerman products. You have to consider your specific needs. I needed some highly portable oscilloscopes for use when out and about, but as I have stated before...you pay a premium for the portability. I would always recommend a bench oscilloscope over a portable model if bangs per buck is a factor. I just bought a lovely analogue Hameg HM1004-3 scope for GBP120. Its a nice bit of kit with a true 100MHz bandwidth. You just have to consider your true needs carefully before spending your hard earned cash. I like all of my oscilloscopes, but for differing reasons. Do not discount buying used equipment from a reputable seller.

Aurora

[saturation]

The Velleman's are decent scopes for the money,  but the Uni-T 81D is a better general purpose portable scope as it give more bandwidth for your $$.  However, that said, if you have a specific need, why spend more?

A principle reason to have these types of scopes is to insure the inputs are truly floating, most all desktop scopes use earth ground, the only way to remove it is to float the scope, which is hazardous, or use special probes. 

For example, if you probe the inputs of a benchsupply with a standard DSO, you will very likely get a huge bunch of noise, and good sized ripple if not more artifacts; this is partly because the scope's earth ground and the probes form an aerial and pick up RF, and if you have the common ground on a bench supply, add to it ground loops.  With a truly floating scope, this is far less a concern.

Verification deletes my message but at £89 is this a bargain or is it worth another say £50 for something else? mine is due tomorrow.

[popultek]

How great a Handheld Oscilloscope. Is made in China?

[saturation]

IIRC, Taiwan.  While well made it has its faults as this thread describes but its good enough for low frequency and low power work.

[grepas]

A thread-bump, but because this has a high Google rank for people searching on info for this machine I am going to use it to note out a couple of drawbacks, and please correct me if I am wrong about them:

"You get what you pay for" sure is appliciable in this case, nevertheless, this machine is very usable for some field work but:

-It comes with no real manual (the "manual" is just a short guide). You essentially have to figure it out yourself. There is no real official manual on the Web either.

-No trigger indicator (which is important in single-shot mode). Haven't seen this on any other scope.

-Autoranging works, to be honest, so-so. It is very easy for the scope to go into "bananas" mode where it cannot decide what ranges to use even with rather simple waveforms. It just jumps around. It would have been better for it to simply decide on something at some point, so it can at least display a stable waveform to the user.

-No way to save startup settings. At least for me, this would have been much more important than the now existing ability to save waveforms.