MC-E separately adressed Solid+Blinky

[marcopolo]

This would really confuse people!! I was handling an MC-E the other night and something occured to me (can't see the wood for the trees moment!!)

It would be possible to address a single MC-E with say 2 solid on dies and 2 dies adressed separately at the same time running blinky!

It would look strange I reckon - with the appearance of never being off yet blinking at the same time. Maybe a bit pointless?!? Somethiing to mull. You would of course have to use a dual driver setup or driver for the blinky and resistor for the solid.

As side question what is the most simple circuit (in terms of discrete components) to make an LED blink?


HHmmmm.

 

[herbicide]

As side question what is the most simple circuit (in terms of discrete components) to make an LED blink?

Base something around 555?

 

[Steve K]

The result of having 2 of the 4 dice blink is the same of modulating the intensity. i.e. it'll change from full brightness to half brightness. Sort of like having the florescent lights flicker. It'll be more annoying than anything, both to you and observers. I've seen some motorcycle headlights that display this sort of behavior.

The 555 is a very handy device for building oscillators like this. For low voltages, the CMOS LMC555 works very well. For higher voltages, the plain bipolar version, the LM555, is good.

regards,
Steve K.

 

[Eamon]

The "see me" factor is why motorcycles run headlight modulators in the first place. The changing intensity doesn't increase the lumens to the road, but it's d*mn sure visible.
If you want to combine "see with" and "be seen by" in the same light, I think that's an excellent idea. You could incorporate a switch to restore the constant beam for higher speeds, If you felt like being extremely annoying, you could blink all four dies.
If you do this, the only thing I would be very careful about is the aimpoint of your light. I set beam height on the bicycle just like I do on the MC, and for the same reasons. High-intensity blinkies are a real hazard if badly aimed.

Eamon

 

[ellerbro]

As side question what is the most simple circuit (in terms of discrete components) to make an LED blink?

I'm currently building one myself that does exactly what you describe, switching between low and high current. Schematic here. 6 resistors, 1 cap, 1 comparator, 1 MOSFET, 1 LED, 2 AA NiMH batteries.

 

[marcopolo]

Ellerbro, i'm looking at your scematic but I can't figure out how you are getting enough Vf?

The LED is only seeing 2.4-2.7v from the 2AA cells as far as I can see, being some constant current (through R6) and some current gated (through R5, U2)

What am I missing?

thanks,

Marco.

 

[marcopolo]

Think i've answered my own question. you RED luxeon has a Vf min of around 2.3v. Not so for my XR-E's/MC-E's!!

Nice circuit though i'd have to use 3 cells!

Marco.

 

[ellerbro]

You could run two of your dice off resistors or a constant current driver, then run the other two dice off another driver controlled by the oscillator output. The 555 IC that others have mentioned can replace the comparator I used if one prefers.