Working on the board layout for @Ash 's circuit. I will likely mess with it on a small prototype board before ordering in an actual board. The circuit as of this moment in time will only be used in two flashers so I don't think I can justify the cost of ordering in custom boards... however If I start replacing controller boards in other lights. perhaps it might be worth while to evolve from proto-boards to real... who knows what the future holds.

this mock up is not done yet. I am sure I made a mistake somewhere I will find later. I am not well rested lol.

I see you have very small clearances at a few places, which will likely lead to short circuits.
Learn to set up and really use DRC (Design Rule Check) function of the CAD software you are using on your designs and rigorously clear all real violations.
With the rules don't push the manufacturing (that includes your ability to solder things without shorts) to the limits by e.g. allowing smalled clearances or distances, it will bite you into your rear later...

Build it on a plug-in solderless breadboard and get a sense of it before you even start soldering

That is my first step with many circuits, including ones where i am really pushing the breadboard limits (switching power supply on a breadboard is significantly affected by stray capacitance, but still useful to weed out all sorts of overlooks and errors, and get sense of component values beyond the initial estimation/calculation)



The capacitors are mostly <1uF ceramic (use Kemet Goldmax series). They are small and flat (you can fit them side by side at 0.1" spacing, at least as long as you dont put 1uF or more in there), except the 10uF one which is a little cube (would fit in 0.2" space)

Some ceramic capacitors have 0.1" and some 0.2" lead spacing. See what's available where you get them

The 10uF is the only one which you are likely to switch to an electrolytic, like if you want to put something of higher capacity in there, or due to cost (an electrolytic probably cost less than 10uF ceramic), though it may have a little higher leakage. Placing 2 parallel spots for ceramic capacitors is also an option




What you have drawn is well within the capabilities of all PCB manufacturers and even low tech PCB manufacturing, but here is a consideration about leakage currents :

The high resistor values (chosen to save battery) mean that the circuit is sensitive to leakages from contamination/dampness. Specifically the networks connected to high impedances : Pins 2, 6, 5 of both 555's, link between D3 and R6, Gate of output MOSFET

Avoid making those traces large or shoving them in tight spaces if possible (where little contamination on the board surface may make a significant resistive leakage between them and something else)

For the final production, go for a board with solder mask to isolate most of the trace surface, and protect it with conformal coating if needed



DRC is a useful tool, but it does not tell the whole story

DRC (in its most basic form) just verifies that you keep the minimum set distance between traces, an other distance-based rules

Here we are talking about contamination, essentially a parasitic film resistor. Obviously, the width of the film (length of parallel traces) will affect the resistance just as much as length of the current path (distance between parallel traces). DRC does not say anything about trace length. It is up to you to design in a sensible way

Even when it is about voltages and flashover distances (typical use case of DRC), electrical breakdown is a statistical effect. If the safe distance for a certain voltage is 3.0mm (for example), a board filled with comb pattern of traces spaced at 3.0mm (pefrectly ok according to DRC), will be much less reliable and less safe than a board with reasonable design, where in one spot the distance is 2.95 (which will make the DRC flag it)

And then there are all the additional considerations : Is it about distance between 2 open solder joints ? Is it between 2 traces, both insulated by solder mask ? A solder joint and a trace ? etc



I would recommend leaving an option for assymetrical duty cycle of the fast flicker for further experimenting (add place for a diode and resistor like D3+R6 in the 2nd 555)



If you want the Kicad file just ask. (Also, i highly recommend Kicad in general both for circut drawing and PCB design, it's my main tool - Along with Qelectrotech for electrical wiring drawings)