hello guys,
iam trying to make a led flasher for my bike.
its like night rider circuit.but i want the led sequence in a different way.
all i use is 5 Leds
pattern shld be
1-ON<-next->2-ON<-next->3-ON<-next->4-ON<-next->5-ON (one by one) when 5 is ON all the LEDS shld stay ON forever.
again when i power OFF and ON the supply the same sequence shld repeat.

if any one has worked on such ckt.pls help.
thanks

 

Isn't that a lot of effort to go through just to gets the lights to turn on a certain way and then stay on? (UNless you are using poweroff to reset the whole cycle).

I guess you could just attach vastly different capacitors across each LED so they all power-up and different rates. They'd probably have to be huge though.

Or maybe a chain of LEDs and D-flip flops (latches might also work) where one end is being fed by a 555-timer and logic HI (straight from the regulated source), so each cycle causes the signal to propogate through the chain (and turn each LED on as a result). But as I said- a lot of effort just to get something to turn on a certain way and stay that way.

 

Should be Easy enough using a 555 oscillator and a 4017 and a Manual Reset.

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An LM3915 can be set up as a bar-graph (up to 10 LEDs) and used to indicate the voltage of a charging capacitor. A switch would discharge the capacitor quickly then it can start all over again.
The LM3915 has a logarithmic scale so the LEDs will light smothly as the capacitor's voltage rises exponentially from a simple resistor. An LM3914 has a linear scale and its capacitor must be charged with a constant current source.

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Uncle $crooge

 

can u post a sample ckt of it.

 

i found this ckt.but i think the cycle will start by itself.no manual reset.and it seems only one led will light up at a time.
http://www.charlton.vic.edu.au/mark/...s/k-rider.html

 

The 1st circuit is a true Knight Rider because a single LED lights going to the right then back to the left and back and forth forever.

The internet has hundreds of chaser circuits using a CD4017 sequencer IC. Only a single LED lights at a time.

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Uncle $crooge

 

thanks.
but i want all the leds to light up one by one and stay ON.(intill i won't reset the supply)
is it possible with 4017?

 

The 4017 lights one LED at a time. The LM3915 can light in a bar with the bar getting longer until all the LEDs are lighted then stay on as long as you want.

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Uncle $crooge

 

well i have 2 LM3914.i think i can use them for this ckt.
i understood the circuit when i saw data sheet.except one what i shld do with the pin5.which is signal input for the chip.
can u give me some rough diagram of ckt which will serve my purpose.
i'll be thanks full.

 

The datasheet for the LM3914 shows it as a voltmeter. Then use it with a constant current source charging a capacitor and it shows the capacitor's voltage as it charges. Discharge the capacitor quickly with a switch or a pushbutton.

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Uncle $crooge

 

i found one design from datasheet.and another from net http://www.cpemma.co.uk/bargraph.html

if i remove the VR1 from above design and place a CAP(10uf),will it work?
and below is the modified ckt

Attached Images

1.GIF (6.7 KB, 22 views)

 

I modified the circuit so the capacitor charges by the 1M resistor. A 10uF capacitor will fully charge in about 10 seconds. The switch resets it.
It uses an LM3915 so that the capacitor seems to charge in a straight line. An LM3914 will have the capacitor begin to charge quickly then slow down near the end unless it is charged with a constant current source transistor circuit.

Attached Images

LM3915.GIF (6.8 KB, 16 views)

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Uncle $crooge

 

thanks a lot guru.
if i use transistor circuit to charger the CAP can i avoid the reset switch.
some how i have to avoid the extra input imean resetting the switch.

 

You don't need a reset switch. You just need something to completely discharge the capacitor when the power is turned off. The way it is now the capacitor might never completely discharge. Then the next time it is turned on the LEDs won't start at the beginning.

A constant current source transistor circuit can charge the capacitor so an LM3914 can be used, instead of using an LM3915 and just a resistor to charge the capacitor.

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