Mixing pic codes

[MartinMueller2003]

non-pwm does dimming by sending a single fixed width pulse to the triac at a point in the AC cycle that will give the desired output intensity. This method counts on the triacs ability to latch and stay on when the pulse goes away. If you are really early in the AC cycle (>80% intensity) or really late in the AC cycle (<30% intensity) there may not be enough current flow through the triac to cause it to latch on. Adding a resistive load (aka snubber) would increase the minimum current drawn by the string and allow the triac to latch. Switching to a triac with a lower latching current helped extend the useful range of dimming.

PWM mode sends a variable length pulse that starts at some point in the AC cycle and stays on until just before the zero crossing point is reached. In this way, the controller does not care what the latching current requirements are in the triac. The triac is actively driven by the controller for the entire time it is supposed to be "on". As you can imagine, this causes more wear on the opto isolator LED used to drive the triac and draws a few mA more current from the controller PSU. On a device designed for continuous 'on' operation of 20 years or more, you would not need to replace an moc due to PWM within your lifetime (or your kid's lifetime).

Since we buy electricity at a rate of 0.70USD / Kilo Watt hour, the increase of current by even 5ma to the moc costs you:

cost per watt = 0.70 [KWH] / (1000 = 0.0007 USD/Watt
watts per triac opto = I * E = 0.005A * 5V = 0.025W
cost per channel at 100% brightness to drive the triac for 1 hour = 0.0007 * 0.025 = 0.0000175USD/hour

For the non-pwm mode you would divide that cost by your line frequency (60hz USA) = 0.0000175 / 60 = 2.916666666666667e-7 USD per hour at 100% intensity.

The place where the power used per channel gets more expensive is when you have an additional indicator light per channel. The extra current for those indicators will not cost you a lot of money to run (Add 20mA / channel) but it does have an impact on the controller PSU. That PSU now needs to supply that extra current. With todays large PSUs, this does not matter. However, my ren64 has 64 indicators and that will have an impact on the size of transformer and regulator chosen, which increases the cost of building the controller.

The point here is that if the PSU on your controller has the capacity to provide the extra current to drive the moc device then there is no real reason to use non-pwm and it is VERY likely that your controller will have the needed capacity to drive the moc using PWM (nobody cuts their design so close that a mA or two added load is going to cause an issue.

[JohnByrne]

Good stuff! Thank you. Again, it's been a minute for me (cough 16 years yikes).

[ctmal]

If you do have flicker issues after switching you can always add a resistor to all the outputs. Or just the outputs that are having issues. I did this on mine just in case. It's not pretty with the xmus boards but with some wire and some wago connectors it's doable.