Signal Generator???

[JohnS_AZ]

I followed a link in another post (which I can't seem to find now) to this seller. Seems like they have some good prices on bare protoboards and some displays. But in poking around, I found what has to be the Worlds Most Stupid Signal Generator Kit ...

http://iteadstudio.com/store/index.php?main_page=product_info&cPath=17&products_id=186

Dumb as it is, it's amazing they can sell the thing for $4.50 US.

[djsb]

Can't even get the MCU part number correct. It's listed as 80C2951 but AT89C2051 on the larger image. Looks like a simple R2R DAC design judging by the number of resistors.

[Zyvek]

I think that company is a division of Dave's favorite Chinese brand.

They seem to have a number of good prices on some familiar devices.

[JohnS_AZ]

No where does it say what the frequency output actually is. And if you look at their scope photos all 4 waveforms are output at different frequencies!  I guessing the big glitches are from using 10% resistors in the D/A.

Man, crap like this makes me think "I really ought to get into the kit business!"

[DavidDLC]

You get this unit and make a hack on the program to make it variable !

Is a good price including the PCB !

[Bored@Work]

$4.50 is IMHO ok for such a toy. Toy as in soldering exercise. But they should really mention that this is in no way a serious signal generator.

If you want a variable on with better quality and source code http://www.myplace.nu/avr/minidds/index.htm

It is IMHO also not the most simple signal generator. E.g. the classic dual OpAmp square and triangle signal generator needs less parts, is equally crappy :-), and is adjustable with two pots.

[JohnS_AZ]

Or you could build Dave's ...

http://www.alternatezone.com/electronics/dds.htm

(although the board art is probably no good ... seems the AD9835 is only available in TSSOP now)

[Zero999]

The frequency isn't adjustable

The amplitude us fixed

No source code provided.

What a load of crap!

This gives me an idea: use an MCU with an RC oscillator for the clock and vary the capacitor and resistor to adjust the frequency. Oh maybe not.

[slburris]

Change the frequency by changing the crystal?  Who would buy something
like that?  Oh wait.... isn't that how old CB radios used to work?

If you only need square waves, a simpler circuit is a TTL can oscillator.
$1 or less, 1 part :-)

I'm not an analog guy, but even I wouldn't use a micro for this.
For the same $5, how about this signal generator from Velleman.
Offers 4 output types and the level is adjustable!

http://www.mcmelectronics.com/product/80-7356&CAWELAID=445498319

manual here: http://www.vellemanusa.com/downloads/0/minikits/manuals/manual_mk105.pdf

Scott


Scott