[aprssig] Timer Circuit Needed

[John Scherer]

John,   Were you able figure it out the circuit from the website?  I  
breadboarded one last night (just for the heck of it)  One thing - it  
seems that  ambient temperature effects the timing by  maybe 20%.   
Other than that it worked well.  I also was NOT using a low-leakage  
type cap like a tantalum or NPO that the website mentions.  They will  
give you better results with long duration timings.  Also I would  
look at using the 7556 cmos chip or the TLC556 if your running from  
battery; I also think they have better thermal stability.   Let me  
know if you want the schematic.

In case the link I gave you before didn't work try this one:

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

For some reason the link I passed to you didn't work when I tried to  
go to it but the one above works.

-John


On May 24, 2007, at 5:14 PM, John wrote:

> John Scherer wrote:
>> 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
>
> Thanks
>
> John
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