OP here,
I had a look at an LM555 datasheet, and it indicated that the max. output current was around 200 mA. The light I'm driving is an off-the-shelf LED automotive taillight which *may* come under 200 mA, but I haven't tested it (there were no ratings on it). Since the light isn't at my desk I can't check right now (I wouldn't be surprised if it was up in the 0.5 A - 0.8 A range). In all likelihood I would end up using a FET of some sort; for my application, it needs to be on the high side of the load.
I have tried the LED blinking lights (generally they run on 3V = 2 x
1.5V batteries). However, IMO they just aren't bright enough for my application...they have enough intensity from directly behind the light, but trail off dramatically when you move to the side.
The application is a bicycle taillight. I found a 12V LED light that has excellent visibility from all relevant angles. Traffic in my area is generally ignorant of cyclists, so anything to grab their attention is a good thing (ignorant != malicious). I already run a 20W halogen up front, so powering the light is not an issue. The taillight has a low- and high-intensity mode...so I want to be able to run the light constantly 'low' and strobe the high-intensity light for approx 0.1 second at a frequency of around 2 Hz. This would hopefully serve to make me more noticeable, drain less power, and keep me legal (the light is constantly on).
Someone mentioned the use of a bimetal flasher...this sounds interesting, I will check it out. I may not find one with the flash frequency/duration that I am looking for, and even if I do the size and/or cost of the device may be prohibitive.
Cheers, Dave