On 2005-10-03, default wrote:
On Sun, 18 Sep 2005 16:48:48 +0100, "Oliver Hannaford-Day"
wrote:

You could scrap the 555 for a variable resistor hooked to a capacitor and
transistor, the resistor would mean the cap would charge slowly (And as such
the voltage would climb slowly) until the voltage was such to activate the
transistor which would ground the cap and restart the sequence.. a nice
simple oscillator for you. :-)

Have you actually done that? Seems more likely the transistor would
gradually rise into conduction as the base voltage climbed to .6 volts
or so. At that point it would limit the voltage from rising further,
but not discharge the cap . . .

use common collector configuration, (aka emitter follower)

What you propose (a relaxation oscillator) would probably take more
than one transistor, or an Thryistor or Unijunction transistor.

I think the plan was a delay after the button is released.


--

Bye.
Jasen