Re: coutdown 555 timer values?

Byron A Jeff wrote: 
In article <PbadneIRNJZWU37fRVn-hA@xxxxxxxxxxxx>,
John Popelish  <jpopelish@xxxxxxxx> wrote:

John Fields wrote:


I'll bet you could come up with something neat based on the 4015 shift register. 


That's probably a better single purpose idea. The basic idea would be
to use a shift register with a master clear input. The start of the timing
cycle would be a master clear starting all 6 outputs. Then each 30 seconds
the opposite bit is clocked in.

BAJ

Yes, I like this. A '164 has 8 outputs, so his 6 output thingy could use a single shift register. He may even be able to drive the LEDs using it, through a resistor (if he doesnt' use a cmos part.) The 555 should use 1M, 1k, and 47uF as the timing elements, so it pulses every 30 seconds or so.

The '164 master reset pin is the 'start' signal, and should also be tied to the 555 reset pin. Bring them both up, and the thing starts counting. Once finished, bring them down, all the outputs clear, and it stops counting. If he wants it to cycle, tie these pins to the Q6 output through an inverter, possibly a CE transistor amplifier.

--
Regards,
 Bob Monsen

If a little knowledge is dangerous, where is the man who has
so much as to be out of danger?
                                 Thomas Henry Huxley, 1877
.