Configuration

Note 1: output voltage

Voltage references:
REF102: 10V
REF02: 5V (omit C₄₄ with REF02)

Please note: R15, R16 and R17 have to be of the same value. If you alter R15 from 10k then you have to alter R16 and R17, too. 10k is default and recommended.

output voltage determined by VoltageReference, R₂₀ and R₁₅:

U_out	= U_ref * ( 1 + (R₂₀/R₁₅) ) V
	= 10 * ( 1 + (6200 / 10000) ) V
	= 16.2 V

determine R₂₀ for given VoltageReference and target output voltage:

R₂₀	= ( U_out / U_ref ) - 1 ) * R₁₅ Ω
	= ( 16.2 / 10 ) - 1 ) * 10000 Ω
	= 6200 Ω

Note 2: Voltage drops across stages

output voltage of preregulator stage, voltage drops across stages

configure voltage drop across the voltage regulator to at least 3V (target range: 3V to 5V)
output voltages of the opamps should be at least 5V below the rail voltages (target range: 6V to 7V, max: 8V)
adjust output voltages of the regulators accordingly, using trimpots R₁₈ and R₁₉

U_out (target) =U_{out_opamp}	R₂₀	Transformer	U_rectified = U_{reg_in}	drop across regulator	U_{reg_out} = V_{CC OpAmp}	drop across opamp
V_out_+ : GND		IN_1_a : IN_1_b	TP₁ : GND	TP1 : TP2	TP₂ : GND	TP2 : V_out_+
GND : V_out_-		IN_2_a : IN_2_b	TP₃ : TP₄	TP4 : V_out_-	GND : TP₄	TP4 : V_out_-
±20V	10kΩ	2× 22 VAC	29,6 VDC	3,0 VDC	26,6 VDC	6,6 VDC
±18V	8kΩ	2× 22 VAC	29,6 VDC	4,0 VDC	25,6 VDC	7,6 VDC
±16V	6kΩ	2× 22 VAC	29,6 VDC	5,5 VDC	24,1 VDC	8,1 VDC
±16V	6kΩ	2× 18 VAC	24,0 VDC	3,0 VDC	21,0 VDC	5,0 VDC
±15V	5kΩ	2× 18 VAC	24,0 VDC	3,0 VDC	21,0 VDC	6,0 VDC
±12V	2kΩ	2× 18 VAC	24,0 VDC	4,0 VDC	20,0 VDC	8,0 VDC
±12V	2kΩ	2× 15 VAC	19,7 VDC	2,7 VDC	16,7 VDC	5,0 VDC

When using a transformer with more than 18VAC secondaries then select capacitors (particulary electrolytic and tantalum) with a voltage rating of at least 50V instead of 35V.

resistor precision, thermal drift, fine tuning

VoltageReference adjustment with optional trimpot (pin5 of REF102(trim out), fine tuning, temperature compensation)
R₁₅ / R₁₆ / R₁₇/ R₂₀ ... precision, thermal drift

Note 3: current rating

max current limited by: inductor in the output path (up to 1.2A) / LM317 (1.5A) / OPA544 (2.0A)
max continuous current: about 1A

Note 4: heat dissipation

voltage drop across LM317 × current draw = dissipated heat from the regulator
recommended drop: between 3V and 5V
voltage drop across OPA544 × current draw = dissipated heat from the opamp
recommended drop: between 5V and 7V
dissipated heat × 4K/W (heatsink) = temperature rise of the heatsink above ambient temperature

Voltage drop [V]	current draw [mA]		heat dissipation [W]	temp rise of heatsink above ambient temp [°C]	junction temp at 25°C ambient temp [°C]

Dynalo PSU