I have this circuit working on my breadboard. This circuit does exactly what I need in term of effect but so far I have not been able to find a way to get more current to the LED output. I need to be able to run either this circuit or one that does the same thing but with a 1/2 watt or 1 watt LED. I also need to be able to manage or set the strobe rate.
Is it possible or possible to use some variation on this?
I tried using a couple of different Darlington transistors (the one on the breadboard now is a Fairchild Transistors Darlington PNP Epitaxial Sil US HTS:8541408000 ECCN:EAR99
No luck so far. When the BC557 PNP is replaced by the Darlington the circuit powers the LED up slowly (too slow) then it fails to shut off.. Q1 does not turn off.. Apparently for some reason the discharge of the electrolytic does not drop the voltage low enough to turn off Q1 let alone keep it off for any length of time.. I tried a few changes of resistors but no luck.. Apparently I have not fully grasped the dynamics at work in how/why Q1 shuts off and why the Darlington has changed this.
I am still new to this stuff though I have been studying up...
I need to get this circuit or a very similar one to FULLY power optionally a 1/2 watt LED or 2 half watt LEDs, so from 120ma to 240ma, depending on resistors. Edit(and power input is really 5vdc)