led chaser help please

[awol]

i would like to buy or build a 8 led chaser
9v -15v
hard to explain but i need 8 led's in a row with it lighting 4 & 5 first then 3 & 6 then 2 & 7 then 1& 8 till they are all lit, so for each pair to stay on till they are all lit ,then for it start again,i dont want any switch's , so it can work as soon as a power supply is introduced, would be handy to have a pot in circuit to adjust speed ,
any ideas is this possible can i buy it or has anyone got a wiring diagram for it
many thanks
awol

 

[colin55]

This circuit will do it:
http://www.talkingelectronics.com/projects/200TrCcts/images101-200/bikeLeftCct.gif

 

[awol]

thanks for the link
it shows 5 led 's
i need eight ( 4pairs to light in turn)
is there any speed adjustment there
sorry i am new to this

 

[Reloadron]

The circuit colin linked to used 10 LEDs as 5 pairs of 2. The last stage could be dropped giving you the 8 LEDs you want. Just modify the circuit. The circuit is driven by a 555 timer configured as an astable multivibrator. The frequency can be made variable by replacing one resistor with a pot in the 555 circuit so again just modify the circuit.

Ron

 

[awol]

thanks for the reply
do i remove and fit the pot where that resistor is at number 6 and 7 at the 555
would they be 12v leds
sorry for the newbee questons
will have to sort out a parts lists thanks

 

[awol]

have ordered the parts
figured out they are 2v red LED'S
dont understand what makes them go off in sequence though
anyone enlighten me
thanks

 

[colin55]

dont understand what makes them go off in sequence though

You never asked for them to go off in sequence.

 

[awol]

hi colin

i wanted to create a smile in leds
the middle 2 to come on then the next pair and so untill they are all alight

how do they light up in the diagram attached by you
thanks
keep smiling

 

[colin55]

How do LEDs go off until they are all alight???

You created a smile, just in your English.

 

[awol]

ok its a langauge thing ie slang like when you say a firework has gone off. it does not mean it has gone out it means it exploded / lit up /took off etc

have edited previous post

keep smiling
thanks