Klaas Robers wrote:Ok Andrew, and now for the maximum brightness....:
Thank you for the above information. I might go this way, but before I do, a question or two...
Am I correct in assuming that the 'bleeder resistor' is there to gradually (slowly) discharge the capacitor(s) solely to make the circuit safer after it has been switched off. That is, to reduce the likelyhood of the capacitors discharging an unpleasant shock if touched accidentally?
You are correct that I have left the gamma resistors untouched. I considered changing these, but I figured they were close enough to allow me to get a picture up and running first (my main goal) and they could be adjusted to improve the picture later.
I understand your calculation that there is only 5mA going through each string of LEDs (40mA / 8 strings). I also understand that the LEDs can be 4x brighter (or more, they handle 35mA, right? -- that's 7x brighter). What I don't quite "get" yet is why we increase the voltage/power supply. Couldn't we increase the current? If there were (say) 200mA of current then the current through the LED strings would be ( 200/8 = 25mA ). Wouldn't the LEDs, then, be 5x brighter?
I think I've forgotten the relationship between the "R" of the gamma circuit and the voltage/rating of the LEDs. I have to think about this some more, and go back through my earlier notes in this thread.
More to the point, though, I'm loathe to play with voltages that are approaching "dangerous". Remember this is my first ever electronics project and though I'm trying to be careful, I have already made a mistake or two. Sparks, yes... smoke, yes... but not any shocks (yet, fingers crossed, touch wood). Playing with 70V would make me very nervous indeed.
There's another thing, I'd find it quite elegant running all this (the sound circuit, the LEDs, the motor, and your boards... from a single transformer/rectifier. At the moment, the sound and motor are running from different supplies... but I plan to experiment and see how things look when driven from the same source.