[aprssig] Timer Circuit Needed

[John Scherer]

I haven't played with the 555 for a long time but basically you want  
a 556 chip.  The first chip is configured for Astable operation and  
its output is feed to the second timer which is configured for  
Monostable mode.

See this site:

http://www.electronics.dit.ie/staff/mtully/555%20folder/555%20timer.htm

-John

On May 24, 2007, at 3:25 PM, John wrote:

> Acuracy is not critical. About 15mins is good.
>
> John
>
> Stephen Brown Jr wrote:
>> I don't have much experience with a 555 or a PIC for that matter,  
>> but I would seem to think a PIC would be easier to implement and  
>> possibly more accurate.
>>
>> Just a thought.....
>>
>> 73's
>> Stephen
>> K1LNX
>>
>>
>> On 5/24/07, John <johnk.mchugh at att.net> wrote:
>> I am in need of a schematic (or complete unit) for a timer that  
>> will run
>> off +12v and pulse a relay every 15 mins. The relay should stay on  
>> for
>> 10secs. I think it can be done with a dual 555, one for the 15mins  
>> and
>> the other for10secs.
>> Anyone got any ideas. I need this to turn on the TNC and  
>> Transmitter for
>> a solar powered wx station I'm trying to build
>>
>> Thanks
>>
>> John
>>
>> --
>> John Mc Hugh, K4AG
>> Coordinator for Amateur Radio
>> National Hurricane Center, WX4NHC
>> Home page:- http://www.wx4nhc.org
>>
>>
>>
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>
> -- 
> John Mc Hugh, K4AG
> Coordinator for Amateur Radio
> National Hurricane Center, WX4NHC
> Home page:- http://www.wx4nhc.org
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