Hi all,
I have to design circuit where 1st led on than 2nd led on .When 2nd led on the 1st led remain on.when 3rd led on the 1st and 2nd led still on and continue.I have use 555 timer and 4017 counter ic but the led moves and 1st led of when 2nd led on.
Can anyone help me. regards bala
Use an LM3914 bargraph driver.
Dave :)
--- View in Courier:
. +---+---------+ . | | | . [1M] QA|---[1K5]--[HLMP4700>]--+ . | |__ _| | | | . +-O|TR R|O--+---|A QB|---[1K5]--[HLMP4700>]--+ . |+ +---+---+ | | | | . [1µF] 1| 7555 +---|B QC|---[1K5]--[HLMP4700>]--+ . | | | | | | . GND GND Vcc | QD|---[1K5]--[HLMP4700>]--+ . | | | . | QE|---[1K5]--[HLMP4700>]--+ . | | | . Vcc | QF|---[1K5]--[HLMP4700>]--+ . | | | | . [10K] | QG|---[1K5]--[HLMP4700>]--+ . | |___ | | . +--O|CLR QH|---[1K5]--[HLMP4700>]--+ . | +-------+ | . | O 74HC164 GND . RESET--> | . | O . | . GND
-- John Fields Professional Circuit Designer
------------------} +12V | 4017 } | 3------2------4---} [R] | | | etc | [D1] [D2] [D3] | | | | [LED] +--| To transistor driver
Add diodes as shown above. Each output connects to a transistor driver - only one is shown. You must keep the total current drawn within spec, thus the transistor drivers. If you need only
3 LEDs, you can eliminate the transistor and resistor [R], keeping the 3.3K resistors, and connect the LEDs to them. The LEDs (red) would get ~ 3mA each with a 12 volt supply, which might be bright enough for you.Ed
if you need frequency counter - a good solution :
Mires
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