[sdiy] TB303 Slide

[Stewart Pye]

I probably will use an SPI DAC. Not a cheap one though, as the INL 
errors are pretty bad on the cheap Microchip ones. A MAX532 should work 
well. I want two outputs so it still won't cost much more than using 
0.1% resistors.

Regards,
Stewart.


On 5/27/2012 6:52 PM, Tom Wiltshire wrote:
> On 27 May 2012, at 00:36, Stewart Pye wrote:
>
>> I'm designing a sequencer that will have slide and accent capabilities of the TB303 and am trying to decide whether to use a 12 bit DAC or an R2R ladder like the TB303. If I go the R2R route I'll use a decent voltage reference, and probably a 74ACT573 to drive the R2R ladder. This will allow me to drive it from a 3.3V micro, and should have enough current output to obviate the extra buffers in the 303 circuit. I just need to get one and measure the high and low output voltages.
> Personally, I'd use the DAC, particularly if you're driving from a micro. The only reason I can see for doing it the TB303 way is low cost, but whilst that was true then, it isn't so true now. You can buy a cheap 12-bit DAC that will do the job for probably similar money to what all the other bits and bobs will cost you (less if you want a voltage ref too), and it'll be simpler and easier with the DAC.
> Save the micro's IO pins for something useful and stick a cheap SPI DAC on it. If you want "authentic" use a resistor string DAC!
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> My 0.02.
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> Tom
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