Electronics > Projects, Designs, and Technical Stuff
Idea for a tiny function generator
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mdszy:
I've had this idea for a little while, and I'm not sure if there are any huge pitfalls I'm missing that would make doing this a bad idea.

I've wanted a tiny little function generator, and some of the Analog Devices DDS chips seem like a perfect solution.

For instance, I've looked into the AD9834 and it seems like a pretty cool little chip that could do sine, square and triangle waves. It could be controlled with a simple microcontroller setup which would have a display and some buttons or an encoder with a button for control.

The downsides I can forsee are:


* It's kinda expensive, $13/chip in low quantities.
* 75MHz maximum frequency, I think it'd be perfectly usable, but it could be a little low
* Digital amplitude control could be difficult - any suggestions for this?
Other than these downsides, I feel like it would be a fun idea to attempt, and could be really fun to try out small-scale manufacturing and selling it on Tindie if I'm able to make it work well enough.

Thoughts?
ChristofferB:
it's a bit wasteful, but maybe out a digital attenuator on it? I'm pretty sure I've seen small cheap digital attenuator chips flying around somewhere.

maybe you could split the output and have one going to a frequency doubler. 150 MHz would be very decent.

--Chris
mdszy:

--- Quote from: ChristofferB on June 24, 2019, 11:19:52 pm ---it's a bit wasteful, but maybe out a digital attenuator on it? I'm pretty sure I've seen small cheap digital attenuator chips flying around somewhere.

maybe you could split the output and have one going to a frequency doubler. 150 MHz would be very decent.

--Chris

--- End quote ---

so the digital attenuator would provide variable amplitudes? That would be nice, I'd have to see what kind of battery life I could get out of the thing, I have some small lipos lying around that I want to try using for it.

I'll look into frequency doublers too, thanks for that suggestion!
Mr. Scram:
75 MHz doesn't sound low to me. Many generators do only 10 or 20 MHz and even then the square waves aren't that impressive. If you manage to do even 30 MHz with good fidelity, you've got a winning product on your hands.
mdszy:

--- Quote from: Mr. Scram on June 24, 2019, 11:44:47 pm ---75 MHz doesn't sound low to me. Many generators do only 10 or 20 MHz and even then the square waves aren't that impressive. If you manage to do even 30 MHz with good fidelity, you've got a winning product on your hands.

--- End quote ---

I see, thank you! Wasn't quite sure what expectations were for a hobby-grade sort of function generator.
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