LED flasher

Thread Starter

kuxz2008

Joined Nov 16, 2009
84
i would like to know what is the least number of component to use in order to allow the 2 LED to flash at the same time.

how do i then connect the LED flasher to a tamiya car motor if i want the LED to flash only when the motor has stop and when LED to stop flashing when the motor is moving?
 

Wendy

Joined Mar 24, 2008
21,914
Sounds simple. Define 2 LEDs at one time. Alternate, or together?

The other problem is how to sense when the motor is moving.

Something like this could be a starting point...



Pin B will stop the oscillator, So will pin A. If alternating is what you want this will do it.

 

SgtWookie

Joined Jul 17, 2007
22,210
Mitch,
There are many ways to get various duty cycles on a 555 timer.

With the "typical" R1/R2/C1 configuration (R1 to Vcc, pin 7 connected between R1/R2, R2 connected to 2,6, C1, other side of C1 to ground), you're limited to >50% duty cycle. You can get a much wider range of duty cycles by adding a diode across R2. Another way is to use the output (pin 3) to charge C1 via a resistor; but with that method you really need to adjust the control voltage downards.
 

Wendy

Joined Mar 24, 2008
21,914


Even with the second oscillator you can get very, very close. For normal use 50.3% is indistinguishable from 50% exactly as seen by the eyeball.

As for the first schematic, I covered this in detail in my 555 Hysteretic Oscillator article. Interestingly, a 7555 doesn't have this problem, but then it can't drive the LEDs either.
 

Thread Starter

kuxz2008

Joined Nov 16, 2009
84
power suply-either 3v or 9v, yellow colour...
Is there any simpler circuit 2 use other than tis... n is it possible nt 2 use a 555timer?
 

Wendy

Joined Mar 24, 2008
21,914
uhhh, have you looked at the schematics? Both are 555 timers. The first uses one resistor and one capacitor (not counting LED and resistor), the other 2 resistors and one capacitor.

I strongly suggest you read this article, 555 Hysteretic Oscillator, it doesn't get any simpler.

If you want to know how to connect your LEDs I have another article, LEDs, 555s, Flashers, and Light Chasers, that will show you how to do it. You can have two yellow LEDs in series and one resistor, in which case I would recommend a 9V battery.
 

Thread Starter

kuxz2008

Joined Nov 16, 2009
84
i hve try out the oscillator 2 n it work. Nw i wanted 2 led 2 flash at the same time. Hw do i connect the second led?
 

Wendy

Joined Mar 24, 2008
21,914
Try not to use shorthand in your writing, it only makes things harder to read, and this isn't a phone.

Depends on your power supply. If you have enough voltage put a second diode in series, otherwise put a second resistor/LED next to the first.
 

Thread Starter

kuxz2008

Joined Nov 16, 2009
84
i wanted to connect this flasher to a tamiya motor so that it will only flash when the motor has stop nt flashing when motor is moving. How do i then connect this?
 

Thread Starter

kuxz2008

Joined Nov 16, 2009
84
i have posted the schematic. motor run on 3v battery. motor changes direction when relay(RLY) is on.
how do i then connect the flasher to the motor?
 

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Thread Starter

kuxz2008

Joined Nov 16, 2009
84
I wanted to connect this flasher to a tamiya motor so that it will only flash when the motor has stop and not flashing when motor is moving. How do i then connect the flasher circuit to the motor?
 
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