fLED as a clock source?

[HarveyH42]

Haven't tried it yet, but was thinking a TTL/CMOS clock source could be made using a cheap fLED a transistor, and resistor. Maybe not a permanent fixure in a finished project, but I don't own a signal generator, nor keep a 555 circuit handy (so easy to throw one together as needed). But thought it might be simple and useful, students might find a use as well.

Figured I'd post this first, and see its been done, before spending much time re-inventing. Have a huge list of things to do this weekend (huricane season is starting to get busy...).

 

[justDIY]

whats a "fled"?

this? **broken link removed**

 

[Hero999]

Flashing LED?

It's pretty simple, just connect a flashing LED and appropriately sized current limiting resistor in series with the base of a transistor with a pull-up resistor connected from the collector to +V and the emitter at 0V. Don't use an LED as the clock if you need decent accuracy, they're worse than a 555 timer.

 

[justDIY]

how about just a momentary switch and a finger? tap tap tap your finger, presto a clock, and it has adjustable frequency!