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palcal

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Joined: 12/10/2011
Location: Australia
Posts: 1993

Posted: 11:30am 22 Mar 2017

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This months SC has a signal generator based on the Micromite Backpack. I went straight to the ali express web site nominated in the srticle to buy one (about US$11) but they were sold out. However SC are selling them for $25 plus about $10 postage. I must say the rest of the mag was a bit of a bore as usual, bring on the new mag DIYODE it can't be any worse.
I will search the web for the module and see what I can find.
Paul.

Edit. I can't find any on the web maybe someone else may have some luck.Edited by palcal 2017-03-23

"It is better to be ignorant and ask a stupid question than to be plain Stupid and not ask at all"

Bill7300
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Joined: 05/08/2014
Location: Australia
Posts: 159

Posted: 01:05pm 22 Mar 2017

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My Silicon Chip issue has yet to arrive but what exactly are you looking for on the web?

Bill

Bill

damos
Regular Member

Joined: 15/04/2016
Location: Australia
Posts: 74

Posted: 01:33pm 22 Mar 2017

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I uploaded an article last year using this module, which is really cheap and easy to get:

AD9833 Module on eBay

There is discussion
here

The SC article uses a module that has a gain stage and a built in level control.

My design uses and incremental encoder for set the frequency and level, which I prefer by far. I put a lot of work into the code for the encoder so it behaves like a good analog instrument - no matter what frequency you are on, it adjusts the step to allow you to quickly sweep a band with a flick of the wrist. For example, at 1kHz going counter clockwise will subtract 100Hz for each step, while above a couple of kHz it will switch to a larger step.

Dan

TassyJim

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Joined: 07/08/2011
Location: Australia
Posts: 6283

Posted: 02:09pm 22 Mar 2017

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I was caught out when I went looking for the module too.
But Geoff assured me they were still available.
I just had to set my EBay search to world-wide and there they were.
This is the one I ordered:
http://www.ebay.com.au/itm/331851695524?_trksid=p2060353.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT
Or search ebay for "AD9833 DDS Signal Generator Module 0-12.5MHz Square / Triangle / Sine Wave"

Having the gain available makes using it much easier.

Jim

VK7JH
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palcal

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Joined: 12/10/2011
Location: Australia
Posts: 1993

Posted: 07:28pm 22 Mar 2017

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Thanks Jim, I have ordered one.
Paul.

"It is better to be ignorant and ask a stupid question than to be plain Stupid and not ask at all"

Geoffg

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Joined: 06/06/2011
Location: Australia
Posts: 3292

Posted: 01:12am 23 Mar 2017

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For people who do not get Silicon Chip the Signal Generator is described on my website at http://geoffg.net/SignalGenerator.html

Geoff

Geoff Graham - http://geoffg.net

RonnS
Senior Member

Joined: 16/07/2015
Location: Germany
Posts: 121

Posted: 02:15am 23 Mar 2017

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thank you Geoff,

that project looks very professional

regards Ron

jman

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Joined: 12/06/2011
Location: New Zealand
Posts: 711

Posted: 06:28pm 24 Mar 2017

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Hi

I have been playing with Geoff's software and found a small issue.
If you select sweep mode then tap the sweep time +- 5 times in row fairly quickly the following error occurs then the watchdog reboots and all is well again

Could somebody else confirm this is the case or is it just me.

Regards
Jman

Geoffg

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Joined: 06/06/2011
Location: Australia
Posts: 3292

Posted: 11:52pm 24 Mar 2017

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That is an obscure bug. I'm tempted to say that the cure is "don't do it" but I will have a look when I get back.

Geoff

Geoff Graham - http://geoffg.net

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