Re: Wiring 555 Timer as Signal Flasher Honda CT90?

On Aug 29, 1:23 pm, Gerryo <ger...@xxxxxxxxx> wrote:
Hi Folks:

I need a bit of help.
I want to use a 555 or similar timer to activate my signal lights on
my trail bike.
Why do I want to change the original system? I have plans to go to all
LED signals and brake lights so this circuit board is the first step
and the original thermal flasher is not that reliable and does not
work well with low current draw of the LED's.

REQUIREMENTS: I need the circuit board to be a plug in unit so I do
not have to modify the bike wiring to be able to use this board. Note:
This turn signal circuit is always powered by the ignition Switch and
6VDC 5.5AH battery and I don't want to modify this feature if at all
possible..

ORIGINAL SETUP:The original turn signal circuit used a thermal flasher
and did not present a problem as it was in series with the relatively
high current indicator bulbs and was not activated until the manual
signal switch was in L or R position and it gave the flasher time to
heat up and start flashing.

PROBLEM: The replacement circuit ( see this link -http://gerryo.wordpress.com/2007/08/29/555-relay-switching-circuit/ -
to the diagram in my blog) works well with the single exception the
relay and the 555 are always cycling at a 1 hertz rate even when the
signal lights are in the OFF position. This is unecessary use of
limited battery power and will wear the components out quickly. Anyone
have any ideas how I could modify the circuit to intially cycle the
relay for maximum 1 minute when manual L or R is selected,then have
the relay and timer turn off until the L or R switch is selected
again? Disregard the horizontal line passing through the timer this
is a scan error.

POSSIBLE SOLUTION: I was thinking a 556 dual timer as well as using
the Normally Closed position on the relay contacts might be useful in
this situation but I am at a loss on how to connect it. Any ideas or
advice would be appreciated.

Cheers...Gerry

I would approach this problem with a "sensing" circuit. Generally,
you can keep your flashing circuit just like it is. Just sense the
turn signal switch being switched to L or R with a PNP transistor
circuit tied to the circuit board output. When the switch is turned
to either L or R, it ties the circuit board output to ground via the
turn signal lamps. That could turn on a PNP transistor. The
transistor circuit can then turn the 555 timer on and off.

Sorry. I don't have the time to design the whole circuit, but
hopefully this will give you a direction.

BRW



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