Velleman HPG1 Signal Generator

[dexters_lab]

This is kinda a mini teardown of a Velleman HPG1 Signal Generator i picked up, these are £82 (GBP) from CPC/Farnell.

Sine, Triangle & Square from 1Hz to 1MHz

Internal nimh battery, with a weird arsed USB charger.

There are pics of the internals

Interface is a little clunky but easily useable, output works ok upto a point. There is little glitching on the signal, it's downside really is the rise/fall times mean that triangle and square at 1MHz is a joke (see pics).

Signal gets very noisy & glitchy at it's lowest amplitude (see pics)

Note i have persistence on in the scope pics.

Cant see any DDS chip on there so looks like it's run from the dsPIC?

[jancumps]

Did you load it with 50 ohms when testing?

[dexters_lab]

bah!, no...

i blame the interruptions and the beer

[jancumps]

Asking because my generator is way out of spec when measuring it unloaded. It's doing fine for amplitude and waveform when properly loaded

[dexters_lab]

there is no mention of output loads in the (very basic) manual i think its too cheap for fancy things like that

[jancumps]

Datasheet on Velleman's site says 50 Ohms.

[dexters_lab]

Yes your right, will try and test again in the week

[nathanpc]

What's the minimum voltage peak-to-peak that the HPG1 can do? I just want to confirm this. The minimum I saw on your screenshots was 40mVpp.

[dexters_lab]

I dont remember and the battery is flat at the moment so will have to check once its charged

I seem to recall the waveform started to look a bit poor at the low outputs

[Juggle4Evr]

Hi,

I own the HPG1 Signal Generator and as I just got my new scope I thought I'll play around with it. So I opened the HPG1 and was surprised to find a dsPIC33FJ32GP that does all the work. I probed some of the pins and I found that when in sweep mode, the PIC outputs a sync impulse marking the start of the sweep on its pin 21. See the attached pic (upper channel is PIC pin 21, lower channel is HPG1 output sweep, sorry about the quality, just a quick screenshot with a camera).
So it's just adding an additional connector to the case and attaching it to that pin (maybe with a "safety" resistor). Could perhaps use the hole at the back for this strange "service measure point".

Would be quite nice to use that sync output for filter frequency analysis etc.

[pascal_sweden]

There are much better options than the device from Velleman.

Take a look at the device from FeelTech, discussed in details on the thread which I posted:

https://www.eevblog.com/forum/testgear/feeltech-fy3224s-24mhz-2-channel-dds-aw-function-signal-generator/

[Juggle4Evr]

Sure, you can always get something better, cheaper, fancier. But as I already have the HPG1 for one year or so, it's nice to get a hidden sync output for free.

[dexters_lab]

There are much better options than the device from Velleman.

Take a look at the device from FeelTech, discussed in details on the thread which I posted:

https://www.eevblog.com/forum/testgear/feeltech-fy3224s-24mhz-2-channel-dds-aw-function-signal-generator/

indeed, there are way better devices... HPG1 is very close to being useless