I have a fairly complex and elaborate plan for a really cool case theme. The centerpiece of this is going to be one hell of a HD indicator. It starts with the HD activity signal triggering a a 4017 counter (I don't want to elaborate too far until I'm actually making it in case this turns out to be one of my brilliant ideas that never comes to frutition), but I need to modify that signal so that I don't run through the count incredibly fast. I'm thinking that I'll make it so that output is normally low (to the counter), but is thrown high when HD signal becomes active (BTW, is it active low or high for the HD header? I know pin 39 is active low, but I don't know if the mobo header works the same) and remains high until HD signal is inactive for X number of seconds. I think that maybe a monostable 555 timer, tying trigger + HD activity signal together. The output of the 555, with a really really high duty cycle, will be high as long as it is continually retriggered before the output goes low, in which case the counter advances. Now, I've been reading a bit more on the 555, and it seems as though it has trouble at frequencies below 10Hz, which is a barrier that I kind of need to break. Any ideas?
does a 555 have problems with frequencies below 10Hz?? hmm.. i have run them down to 0,75 hz... no problem with that...
That's good to hear Smil, because I was thinking of something around .5-1Hz. bard, I figured as much, but I wanted to be sure.
Bard is right it is an active low signal. Also the connection between Pin39 and the motherboard header is like this: http://www.zapwizard.com/ide/mb_schematic.jpg Nothing more then some pull-up resistors and diodes. More details at: http://www.zapwizard.com/ide
hmm... while at those 555's... when setting the frequency, be sure to use larger capacitor to lower frequency... not only resistors... I have had some problems with oscillators not working due to too large resistor... was fixed by using larger cap and smaller res... that was not a 555 though... i can see that circuits have problems with too high frequencies, but not to low... if not used for measuring of course...
