digital "pots" have been around for quite a while...

[Mike O'Dell]

I was impressed that the amount of capacitance per bit was denominated 
in femtoFarads
measuring that has gotta be more than slightly tricky

     -mo


On 3/20/12 4:44 PM, Phil wrote:
> I'm quite impressed that the capacitance goes that low. Making a five-bit digitally-switched capacitor with standard 4000-series CMOS is fairly straightforward, but obviously you are limited by the stray capacitances present. The Arduino-based crystal set is still on the cards!
>
> Phil M1GWZ
>
>
>
>
> On 20 Mar 2012, at 11:44, Robert E. Seastrom wrote:
>
>> I was disappointed they only go up to 5.5pF.  Nowhere near enough to
>> build myself an Arduino-driven crystal set.
>>
>> -r
>>
>> Mike O'Dell<mo at ccr.org>  writes:
>>
>>> I see - "Sparkgap Defined Radio"
>>>
>>>     -mo
>>>
>>>
>>> On 3/19/12 10:55 PM, Joseph Bento wrote:
>>>> Now if they can make them with the equivalent of 3,000 volt spacing on the plates...
>>>>
>>>> Joe, N6DGY
>>>>
>>>> On Mar 19, 2012, at 8:53 PM, Mike O'Dell wrote:
>>>>
>>>>> this was, i guess, inevitable?  digitally adjustable capacitors
>>>>>
>>>>>
>>>>> http://www.psemi.com/content/products/apps/product_dtc.html
>>>>> _______________________________________________
>>>>> Tacos mailing list
>>>>> Tacos at amrad.org
>>>>> https://amrad.org/mailman/listinfo/tacos
>>> _______________________________________________
>>> Tacos mailing list
>>> Tacos at amrad.org
>>> https://amrad.org/mailman/listinfo/tacos
>> _______________________________________________
>> Tacos mailing list
>> Tacos at amrad.org
>> https://amrad.org/mailman/listinfo/tacos
> _______________________________________________
> Tacos mailing list
> Tacos at amrad.org
> https://amrad.org/mailman/listinfo/tacos