They are necessary if the unstablised voltage goes away faster than the regulated (due to much capacitance, which you don't ought to have)dw8083 said:
Actually, it's fullwave rectification but this will increase the losses a bit compared to using a rectifier bridge. You can save two diodes by this.dw8083 said:
Hi Ryssen,
Depends on what performance you want. This circuit is better than nothing but not nearly as good as you can make.
Normally you start by figuring out what your supply voltage is now, and what your required voltage is. Then you need to know what your minimum voltage is (line droop plus the trough caused by ripple at your maximum current draw) and what the "drop out" voltage of your chosen circuit is, or what it will be if it's close to the existing. You really need headroom to compensate for increased ripple as your capacitors age.
-Chris
Depends on what performance you want. This circuit is better than nothing but not nearly as good as you can make.
Normally you start by figuring out what your supply voltage is now, and what your required voltage is. Then you need to know what your minimum voltage is (line droop plus the trough caused by ripple at your maximum current draw) and what the "drop out" voltage of your chosen circuit is, or what it will be if it's close to the existing. You really need headroom to compensate for increased ripple as your capacitors age.
-Chris
Here's another design using LT1085CT for positive and LT1033CT for negative from Welbourne Labs.
http://www.welbornelabs.com/ps1.htm
-David
Welbourne Quote:
The PS-1 is a high quality low voltage regulated power supply. It is recommended for use with solid state preamplifiers, active crossovers, filters, CD players, and other circuits with low-to-medium current requirements. The PS-1’s voltage can be fixed from +/- 5 volts to +/- 24 volts by the selection of a few resistors, and its output is capable of supplying up to one ampere of current. The regulators are rated at 3 amps, so if your current requirements are higher than 1 amp, a larger transformer can be substituted without altering the present circuit configuration. The supplied toroid transformer can be used with both 120Vac/60Hz or 240Vac/60Hz operation. The figure on page 2 depicts the schematic diagram of the PS-1 circuit. This power supply is similar to the one designed by Walt Jung and Gary Galo and published in TAA and uses the Linear Technologies LT1085CT/LT1033CT voltage regulators. These regulators are low dropout, high efficiency devices highly recommended for audio applications. The main differences between the TAA design and the PS-1 are: The PS-1 uses a smaller VA rated transformer and a lower value output filter capacitance (the 4A transformer was really overkill); More bypass capacitors are used throughout the PS-1 circuit to prevent transients and other supply-related noise from reaching the audio circuitry, we have added the schottky low-noise rectifier diodes, use Nichicon ultra low impedance electrolytics and most importantly the PS-1 is less expensive. Available with or without the toroid power transformer.
http://www.welbornelabs.com/ps1.htm
-David
Welbourne Quote:
The PS-1 is a high quality low voltage regulated power supply. It is recommended for use with solid state preamplifiers, active crossovers, filters, CD players, and other circuits with low-to-medium current requirements. The PS-1’s voltage can be fixed from +/- 5 volts to +/- 24 volts by the selection of a few resistors, and its output is capable of supplying up to one ampere of current. The regulators are rated at 3 amps, so if your current requirements are higher than 1 amp, a larger transformer can be substituted without altering the present circuit configuration. The supplied toroid transformer can be used with both 120Vac/60Hz or 240Vac/60Hz operation. The figure on page 2 depicts the schematic diagram of the PS-1 circuit. This power supply is similar to the one designed by Walt Jung and Gary Galo and published in TAA and uses the Linear Technologies LT1085CT/LT1033CT voltage regulators. These regulators are low dropout, high efficiency devices highly recommended for audio applications. The main differences between the TAA design and the PS-1 are: The PS-1 uses a smaller VA rated transformer and a lower value output filter capacitance (the 4A transformer was really overkill); More bypass capacitors are used throughout the PS-1 circuit to prevent transients and other supply-related noise from reaching the audio circuitry, we have added the schottky low-noise rectifier diodes, use Nichicon ultra low impedance electrolytics and most importantly the PS-1 is less expensive. Available with or without the toroid power transformer.
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