Author Topic: Ebay DDS function Gen problem  (Read 2701 times)

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Offline Deathwish

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Ebay DDS function Gen problem
« on: August 02, 2015, 08:35:42 pm »
Ok.i got this a while back.

http://www.ebay.co.uk/itm/291399023398?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

I have it on my bench attached to a ATX psu, the psu has a mobo attached to let the psu run. The DDS unit keeps displaying daft characters and turning itself on and off randomly. The waveform it outputs on say a sine wave is more like a stair step and a triangle wave is like the same.

Any ideas before i throw it out my window. :rant:
« Last Edit: August 02, 2015, 10:50:55 pm by Deathwish »
Electrons are typically male, always looking for any hole to get into.
trying to strangle someone who talks out of their rectal cavity will fail, they can still breath.
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Offline Isad

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Re: Ebay DDS function Gen problem
« Reply #1 on: August 02, 2015, 10:41:13 pm »
Ok.i got his a while back.

http://www.ebay.co.uk/itm/291399023398?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

I have it on my bench attached to a ATX psu, the psu has a mobo attached to let the psu run. The DDS unit keeps displaying daft characters and turning itself on and off randomly. The waveform it outputs on say a sine wave is more like a stair step and a triangle wave is like the same.

Any ideas before i throw it out my window. :rant:

Try and run it off a battery  :-// :-//.
These are crap things but for the money they kinda are good  :bullshit:.

If you want to throw it off the window i will get.Lol :P
Lifes to Short Make the Most of It

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Offline onlooker

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Re: Ebay DDS function Gen problem
« Reply #2 on: August 02, 2015, 11:16:52 pm »
Check the ripple and noise of your PSU. I have seen tablet having the keyboard typing itself when the PSU noise reaches about 200mVpp.
 

Offline TheMG

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Re: Ebay DDS function Gen problem
« Reply #3 on: August 03, 2015, 03:58:11 am »
the psu has a mobo attached to let the psu run.

No need for that. Connect green wire from the ATX 24-pin motherboard connector to any black wire.

Heck, at work I even have a super special custom paper clip I use for powering up and testing suspect computer power supplies. ;)

Check the ripple and noise of your PSU.

I'd check this too. An all too common problem with computer power supplies is that the capacitors go bad, causing excessive ripple which then causes the computer to randomly crash or not boot up at all. Could be what's messing up your DDS.

Or.... it could just be a faulty piece of eBay garbage.
« Last Edit: August 03, 2015, 04:00:21 am by TheMG »
 

Offline Bud

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Re: Ebay DDS function Gen problem
« Reply #4 on: August 03, 2015, 04:05:07 am »
I was horrified by the seller's oscilloscope   :scared:
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Offline Isad

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Re: Ebay DDS function Gen problem
« Reply #5 on: August 03, 2015, 11:14:56 am »
I was horrified by the seller's oscilloscope   :scared:

Lol look at the trace rotation hole somone must have doen it by hand or somthing good old knifes.
Lifes to Short Make the Most of It

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Offline Deathwish

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Re: Ebay DDS function Gen problem
« Reply #6 on: August 03, 2015, 11:36:14 am »
the psu has a mobo attached to let the psu run.

No need for that. Connect green wire from the ATX 24-pin motherboard connector to any black wire.

Heck, at work I even have a super special custom paper clip I use for powering up and testing suspect computer power supplies. ;)

Check the ripple and noise of your PSU.

I'd check this too. An all too common problem with computer power supplies is that the capacitors go bad, causing excessive ripple which then causes the computer to randomly crash or not boot up at all. Could be what's messing up your DDS.

Or.... it could just be a faulty piece of eBay garbage.

The mobo is only on there to give it a load, not so I can start the psu up. As for it being ebay garbage, i am leaning that way.
Electrons are typically male, always looking for any hole to get into.
trying to strangle someone who talks out of their rectal cavity will fail, they can still breath.
God hates North Wales, he has put my home address on the blacklist of all couriers with instructions to divert all parcels.
 


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