LED 555 PWM 1%-99% suggestions

Thread Starter

knowtankyou

Joined Feb 29, 2016
32
Thank you to this forum for the help on my previous thread. Taking to heart the suggestions made there I have started a new circuit simulation.
please find attached the result of how I interpreted what was suggested.

This 555 circuit uses the discharge and not the output, which I found interesting.
the frequency was in the 200-200 hz range, is that a good operating point for the 555?
I would be open to suggestions on the NPN transistor for SMD solutions, also the FET is just what I grabbed. I assume a lower on resistance is ideal for this application.
have a great day
 

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Thread Starter

knowtankyou

Joined Feb 29, 2016
32
PS, I am still open to suggestions on White LEDs in the 1-3watt range.
directional distribution is preferred to flood, but that is a minor point right now.
I think the LTspice library was showing discontinued LEDs, but I think they are OK for simulation.
 

dannyf

Joined Sep 13, 2015
2,197
I have started a new circuit simulation.
Your previous circuit can be made to work.

For the one you are working on, look for 555-based smps circuits and you can easily repurpose them as a constant current led driver. It is much more efficient than that you have here.
 

Thread Starter

knowtankyou

Joined Feb 29, 2016
32
Thank you Ronv, I will actually have (3) 12V batteries and I hope to make my LED string operate at around 36V.
I agree with your opinion, the losses of one FET vs 10-11 LEDs will be minimal. I just need to get through about 6 hours of night fishing.
33w of LED and lets say 3w loss of this circuit, is doing about 90% efficiency.
and I figure using 6AH to run this for a fishing run.
 
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