limits:
	output voltage: 2V (minimum of lm723) - 28V (max of lm358)
	output current: 3A parallel, 1.5A series (max of transformer)


new features:
	- working current limit :P
	- calculate actual filtering cap value for some value of ripple at 3A
		- I=CdV/dt, C=Idt/dV, dt=8.33ms (one half of 1/60 because full wave),
			for 3Vpp ripple at 3A, 3*0.00833/3 = 8,330uF, (2x 50V 4700uF in parallel)
			for 1Vpp ripple at 3A, 3*0.00833/1 = 24,990uF :o
	- calculate worst case power dissapation value for pass transistor
		- at 100C case temp, 3055 can safely dissipate about 60W
			15V-2V = 13V*3A = 39W (with relay switching xformer leads at 15V)
			should probably still add better heatsink with fan
	- use keyed cable connectors
	- high side current meausurement resistor
		- need to use differential amplifier with good CMRR
	- SCR overvoltage protection

	- relays:
		- on/off switch disables outputs
		- switchable output
		- voltage range switches transformer configuration
			- 2-15V parallel output, 3A
			- 15-28V series output, 1.5A
			- may need to also switch off output when changing the voltage to
				prevent inductive spikes from switching the xformer going to
				the output

	- kicad:
		- virtual symbols for off-board components (ac side protection/switch)
			^ https://forum.kicad.info/t/off-board-components-in-kicad-5/22286