Friday, April 06, 2012

Very Simple Pre-Regulator

Present desire be there many period anywhere it is considered necessary to waste the P05 supply module from a upper voltage source. intended for case, if you lack to add balanced inputs to a power amplifier, next you need a +/-15V supply, but the amp's supply voltage willpower survive much too far above the ground for the manager ICs.
This project is roughly speaking to the same extent unpretentious as they take place, and is very economical to build. It is designed in support of exactly this reason - to reduce the amplifier supply voltage to a safe significance for controller ICs.

The circuit it is very down-to-earth indeed. You desire need to make it to a hardly any simple calculations to determine the resistor value, but this is explained beneath.

Very Simple Pre-Regulator

The circuit made known uses the 24V zener diodes (D1 and D2) to adjust the output voltage to a unimportant under 24V. This is a seamlessly safe input voltage in favor of standard 3-terminal regulators, and using this circuit long for provide even better guideline and supply clamor rejection at that time typical. Using MJE3055 and 2955 transistors will allow for supply voltages up to 70V quite safely, but they will need to take place mounted on a heatsink (with insulating washers).

The single-mindedness of R5 is to detach the foremost power amplifier ground from the supply, to prevent hum loops. The 10Ω resistor revealed motivation be fine in lieu of the vast majority of applications, but might need to remain untouched. This is up to you to research with if essential. I hint at so as to R5 ought to be 1W. R2 and R4 may perhaps be 1/4W before 1/2W resistors, and 1W zeners are recommended.

The lone calculation is to determine the regard in support of R1 and R3. original, quantify the power amp supply voltage (V1). The resistor value is calculated to provide a top figure zener current of 20mA, and this hope against hope ensure sufficient found current for the pass transistors representing up to 100mA before so output current by the side of ±15V.

V2 = V1 - 24 (someplace V1 is amplifier supply voltage, and a 24V zener is used)
R1 = R3 = V2 / 20 (R1 and R3 morals are arrived kΩ)
P = V2² / R1 (P is power dissipation of R1 and R3 in mW)

consent to's begin to have a supply voltage of ±56V meant for an pattern calculation ...

V2 = 56 - 24 = 32V
R1 = R3 = 32 / 20 = 1.6k (practice 1.5k)
P = 32² / 1.5 = 680mW = 0.68W (use 1W)

The dissipation in Q1 and Q2 could as well be located calculated, but you need to know the current drawn by the outdoor circuits. on behalf of instance, if the external circuitry draws 50mA, the transistor power dissipation is ...

Pt = V2 * Iext = 32 * 50 = 1600mW = 1.6W (it self-control need a slight heatsink)

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