Re: Need help with intermittent circuit failures - JK Flip Flops

Thanks guys heaps. You been a great help.
I haven't had a chance yet to try your schematic John (Petrus and ehsjr, I
have noted your observations and advice as well), but I'll let you know as
soon as I've totally rewired my breadboard...ugh.

However, do I really need to add another IC to my board (the 2nd 555)? This
board has to be as small as possible... I didn't think I'd need so much
electronics to do this simple task. Maybe 1x 556 (dual 555 IC) instead of
2x 555 would save a little more space??

By the way - in relation to the way I configured the monostable.... is it
still a bad thing to want to be able to trigger the monostable at power on
(ignoring the reed switch for arguments sake)? Assume pins 1 and 8 were
connected directly to the supply rails... so when power is turned on, the
monostable triggers automatically (due to C2). I understand the correct
method of triggering pin 2 with a negative pulse, but then I would need a
separate circuit to achieve that as well - the negative pulse. That is the
only reason why I connected the reed relay the way I did - When the magnet
comes into contact with the reed, it triggers the 555, doesn't matter how
long the reed is in contact with the magnet for. In my circuit, if I made
it so that the reed switch triggers pin 2, the 555 would freeze (on 'high')
because the motor would have turned off and stopped right in front of the
magnet indefinately. I was just wondering that's all.

The two 15V zener diodes across the motor opposite each other is critical
yeah? Is my Q1 transistor overheating because these are absent? Or because
of the motor reactivating too soon before the relay switches over??? The Q1
is rated 0.8A.

P.S: John, I really appreciate your schematics... makes it a lot easier to
understand what you are talking about =).

Ta
Jason.






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