||24th July 2013 05:01 PM
Originally Posted by HoneyBadger
Maybe I am asking for too much here but could someone post an equation that could help calculate output voltages with variable values represented by the component identifier (for example: R1).
Output voltage ~ (1.4 * VAC) -1.2 (1.2 varies depending on the forward voltage drop of the diodes chosen and operating current, see the data sheets, but 1.2 will get you in the ballpark) Subtract a bit more if you go with the CRC option.
R1 (optional) etc. are your call. You probably want to keep the net of the paralleled resistors under 0.1R although there are bound to be some differences of opinion. If you don't want to go CRC, just jumper one or more positions.
R9, R18 (bleeder) again your call. Pick a value that will bleed off your caps in a reasonable amount of time without dissipating too much heat. Around 50-60V try 4.7K/4+ W.
R21, R28 LED current limiters. You pick to set your LEDs at desired brightness. R = (V-Vf)/I Where V is rail voltage, Vf is forward voltage drop of your LED and I is desired current. Typical values for Vf are blue=5V, green=2V, red=1.2V Probably close enough for calculating R without going into the datasheet. I find most blue LEDs are too bright at 5 mA, YMMV.
R11, R12, C17, C18 - Snubber, optional. The values on the board are general purpose, your needs may vary depending on your particular transformer, rectifiers and capacitors. You can feed your amp high frequency square waves at near max power and look for ringing on the rails as you adjust values. There are ways to calculate values, look for the snubberized thread.
There is a snubber on the rectifier board, also optional, as above.
Hope that helps.