[HBQRP] Looking For A Tone Decoder

[Joe]

Just when it hears a 50 Hz tone (0.5 sec duration) it activates a timer 
that will close a relay for 8 seconds.

Joe WB9SBD
Sig
The Original Rolling Ball Clock
Idle Tyme
Idle-Tyme.com
http://www.idle-tyme.com
On 2/13/2014 8:25 PM, Sean Pepin wrote:
> On 02/13/2014 07:47 PM, Joe wrote:
>> I'm looking for a tone decoder. IE: it hears a certain tone 
>> frequency, and it changes state.
>>
>> Think like a old PL tone thing in a repeater.
>>
>> Joe wb9sbd
>
> What's your application?
>
> The LM567 is probably capable of what you need. From the datasheet:
>
> The LM567 and LM567C are general purpose tone decoders designed to 
> provide a saturated transistor switch to ground when an input signal 
> is present within the passband. The circuit consists of an I and Q 
> detector driven by a voltage controlled oscillator which determines 
> the center frequency of the decoder. External components are used to 
> independently set center frequency, bandwidth and output delay.
>
> Sounds like just what you need, costs about $1.50 in single quantity 
> from Mouser.
>
> When I was young I made a cabinet lock that I could whistle to unlatch 
> with one of these, but it sort of stinks when the batteries run out.
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