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using 1 watt LEDs with a 4017 Answered

I want to build a chaser type light array using a 4017 counter divider circuit, 555 timer and the ever popular 1 watt luxeon LEDs, but I don't think that the 4017, or the 555 can withstand the current that will be going through them. I know in most cases you can simply toss a heatsink on the component and it will be fine, but I don't know if this will work with the ICs.
Here is the spec sheet for the 4017. Thanks


You can try the ULN2803A chip 8 X darlingtons and add a limiting resistor to each as 1W LEDs still cost!


11 years ago

you need a mosfet. see the bike blinker project which uses a 555 & mosfet to drive a 3-watt led.

how do the 555 and the 4017 handle that much amperage

They don't. The 4017 can only handle a few milliamps (mA). But by using a FET transistor, Q1 in the bike blinker project, between the 4017 and the Luxeon LED the current is "amplified" (not scientifically true, but close enough for this discussion). The FET can handle several amps without breaking a sweat. So by connecting a FET transistor between each of the ten outputs of the 4017 and the LED's the weak output of the 4017 is just turning on the transistor which in turn can handle the high load of the Luxeon.