3D pov display Full Design

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How will the PWM control work?

The ShiftPWM library does PWM on '595 shift registers, by rapidly shifting out different patterns. It uses a lot of the CPU time. It works pretty well for stationary viewing. I'm not sure if it's fast enough for POV.

ShiftPWM has not been ported to Teensy3 yet, but it's on my to-do list now that IntervalTimer is included in Teensyduino....
 
The PWM is controlled independently from the shift registers. The shift registers only control if each led is on or not.

All of the leds colours will have a common power, so I can only change the colour in the time dimension.

So the direct pwm from the teensy will switch transistors, to control the colour.

Did I not point that out well enough?
 
I didn't follow that, but it sounds like you have a plan. :)

Might be a good idea to prototype a minimal circuit with just one '595, six transistors and two RGB LEDs on a solderless breadboard, before you go to the trouble of making several PCBs.
 
This schematic?

https://docs.google.com/file/d/0B-UwY1-6XVBrRG5JNTlRckZQdFU/edit

I don't see quite how this lets you control the LEDs in a useful way, but then it doesn't show where the CABLEOUT-6, CABLEOUT-8, and CABLEOUT-9 pins connect. Perhaps those go to another schematic with some really large transistors? Even then, if those 3 lines has PWM at very high current, you'd be able to turn on any combination of the 16 LEDs, but it seems like all the LEDs you turn on at the same time would need to be the same color.

Usually for persistence of vision applications, you would need to turn each LED on to its own color for a short period of time, while it's in a specific position. Maybe this application has some unique property, where the LEDs don't ever need to be different colors at different times?

Or maybe I just missed something. I only looked at the schematic and your write-up for a few minutes, so it's entirely possible I missed some important detail?
 
Yes making a full schematic is on the to do list.

The idea is to have the same main control as a single colour POV, but with background high resolution rainbow effects :)

The tlc5940 is to expensive for me.

It will make good use of the Teensy 3 PWM

You have to admit, it would look cool ;)
 
It you can afford 3X the '595 and NPN transistors, which are really cheap parts, and 3X the time to solder every part, you could have at least basic control of the color of each LED at every position. You'd also eliminate the need for a special circuit with huge (probably more expensive) transistors to PWM control the 3 power lines going to all those LEDs. If you'd on a tight budget, just getting rid of the 3 really big transistors, plus whatever drives them, might pay for the extra '595 chips and cheap NPN transistors.
 
No the circuit actually doesn't cost more, it will cost a bit less.

Using the 3x the 595 means I can only get a few different colours, at the cost of 3X slower update rate.

I think that the higher switching speed with the common control, would make it look cooler than using 3x595s.

With the common control I should be able to get a high resolution and a lot of colours, to make colorful waves flowing across the display. VS if I was to use 3* the 595's then I could colour each frequency band differently with a different shows of amplitude.

Between those two I decided that the common control will bring more to a music visualization, to in a sense compete some of the fancy graphics on some on computer music visualizers

Even if the performance was the same, the common control still comes up as the best option.
 
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