Low Ripple Regulated Power Supply Circuit Diagram

This circuit may be used where a high current is required with a low ripple voltage (such as in a high powered class AB amplifier when high quality reproduction is necessary ).

Q1, Q2, and R2 may be regarded as a power darlington transistor. D5 and R1 provide a reference voltage at the base of Q1. D5 should be chosen thus:
D5=V_out-1.2

C2 can be chosen for the degree of smoothness as its value is effectively multiplied by the combined gains of Q1/Q2, if 100µF is chosen for C2, assuming minimum hef for Q1 and Q2,

C=100×15(Q1)×25(Q2)

=37000µF.

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555 Negative Voltage Power Supply Circuit

A negative supply can be generated by a “Charge-Pump” circuit created with a 555, diodes and capacitors.

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Ni-Cd Ni-MH Adjustable Constant Current Battery Charger Circuit

This is a Adjustable Constant Current Ni-MH or Ni-Cd battery charger circuit. It can be used to get a constant current power supply. Here is the schematic diagram of the circuit:

This circuit can be adjusted to any value from a few milliamp to about 500mA. The max current is 500mA because it is the limit of the BC140 transistor in the current-limiting part of the circuit.

The input voltage has to be 5.25v above the required output voltage, because of 1.25v across the current-limiting section and Approximately 4v is dropped across the regulator.  The LM317 3-terminal regulator will need to be heatsinked.

the LM series of regulator is suitable for this circuit because they have a voltage differential of 1.25v between “adj” and “out” terminals.

For example, to charge 4 Ni-Cad cells, just connect them to the output and adjust the 500Ω preset until the required charge-current is obtained. The charger will charge 4 Ni-Cad cells at the same current. But, don’t forget to turn off the charger before the cells are fully charged or the battery will be over-charged.

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Power Supply Failure Indicator Circuit

Many circuits, especially digital systems such as random access memories and digital clocks, must have a continuous power supply to ensure correct operation. If the supply to a RAM is interrupted then the stored information is lost, as is the time in the case of a digital clock.

The supply failure indicator described here will sense the interruption of the power supply and will light a LED when the supply is restored, thus informing the microprocessor user that the information stored in RAM is garbage and must be re-entered, and telling the digital clock owner that  his clock must be reset to the correct time.

When the supply is initially switched on the inverting input of IC1 is held at 0.6V below positive supply by D2. Pressing the reset button takes the non-inverting input of IC1 to positive supply potential, so the output of IC1 swings high, holding the non-inverting input high even when the reset button is released. LED D1 is therefore not lit.

When the supply is interrupted all voltages, of course, fall to zero. Upon restoration of the supply the inverting input of IC1 is immediately pulled up to its previous potential via D2. However C1 is uncharged and holds the non-inverting input low, so the output of IC1 remains low and D1 lights.

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Tube Amplifier Power Supply Unit Designer Software

PSU Designer II is designed to help you with the design of simple linear (unregulated) mains power supplies, as often found in tube amplifiers.

• Rectifier types: Solid state, Vacuum tube types 5AR4, 5R4-G/GY/GYA/GYB, 5U4-G/GA/GB, 5V3-A, 5V4-G/GA, 5Y3-G/GA/GT, 5Z3, 6AU4-GT, 6AX4-GT/GTA/GTB, 6CA4, 6D22S, 6DE4, 6X4, 6X5/GT, 6W4-GT, 83, EZ80, EZ81, GZ33, GZ34, GZ37.
• Rectifier configurations: Half-wave, Full-wave, Full-wave bridge, Voltage Doubler.
• Filter configurations: Simple C filter, C/R/C, C/L/C and LC (swinging choke).  ESR in capacitors can be catered for, as can winding resistance in chokes.  Chain as many filters together as you like.
• Outputs: Graphic representation of voltages and currents present in the power supply.
• Tools/Utilities: Transformer off-load voltage calculator, transformer source impedance calculator.
• Other features: Online context sensitive help.   Ability to add extra rectifier types.

Vacuum Tube Amplifier Power Supply Unit Designer Software

Operating system: Windows 95, Windows 98, Windows 2000 or Windows NT, XP, VISTA.

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DC Regulated power supply Using 741 Op Amp IC And 2N3055 Power Transistor

The voltage regulated power supply provides an adjustable voltage output at a load current up to 1A. The supply has a built-in overload protection.

Rectifier diodes D1 and D2 along with capacitor C1 provide the main unregulated supply. D3, C2, R8 and zener diode provide a negative voltage supply for the 741. The non-inverting input terminal of 741 is given a stable voltage by R3 which is the control to set the output. A fraction of the regulated output is fed back via R4 and R5 to the inverting input terminal. The operational amplifier adjusts its output voltage so as to keep the voltage at the input terminals equal. Thus the output gets regulated. The output of 741 is amplified by a compound emitter follower T1 and T2.

All the current flows through R6. If the load current exceeds 1A, the voltage drop across R6 exceeds 0.6 volts and T3 starts conducting. This bypasses the supply to T1 and T2 and the regulating action stops. The output voltage therefore starts falling when the load current exceeds 1A. Any of the output terminals can be grounded to get a positive or a negative voltage with respect to the ground.

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L200 Power Supply Regulator

There are applications in which it is important for the supply voltage to be largely independent of the level of the output current, which is, of course, particularly so in the case of variable loads.

When the load is linked to the power supply by relatively short wires, a good variable power supply maintains the output voltage at a virtually constant level. Unfortunately, in practice, these wires can be fairly long, and since they have resistance, there is a voltage drop across them. This interferes with good regulation; the only way of avoiding this problem is to link the control part of the power supply to the load via separate sense lines.

Unfortunately, this cannot be done readily in every power supply without some tedious work, but as the diagram shows, in the case of the L200 it presents no problems.

In the diagram, A and D are the usual output terminals, while B and C are the sense input terminals. The output voltage,  U0, is

U₀=2.77(1+R_p/R₁),

where U₀ is in volts and R_p is the effective resistance of P₁. Resistor R₂ in series with terminals A enables current limiting. The peak level of the output current, I₀, in amperes is

I₀=0.45/R₂

The maximum input voltage to the regulator is 40V, and the peak output current is 2A.

L200 ADJUSTABLE VOLTAGE AND CURRENT REGULATOR PIN Configuration

The regulator has on-board thermal protection, but this does not mean, of course, that is should not be mounted on suitable heat sink when the dissipation is high.

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Under and Over Voltage Protector

A few circuits on under/over voltage protection have appeared recently in EFY. But this circuit is simple, very easy to construct and inexpensive. It can be added to existing stabilisers, in which case DC power supply can be taken from the original stabiliser circuit and only a few additional components, including one relay, are required to make the circuit.

When supply voltage is within limit. T2 conducting and T1 is in a non-conducting state. At low voltage, zener Z2 will not breakdown and T2 will not conduct, which results in de-energising the relay. This adjustment is done by adjusting VR2.

At high voltage, zener Z1 will breakdown and T1 will go in conducting state and the relay will de-energise. This adjustment is done by adjusting VR1. Normally-open contact of the relay is used in control circuit. Red LED gives high low voltage cut-off  indication.

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The circuit described here is of an economical smooth variable power supply which offers 0V to 24V. It provides all controls and short circuit protection with acceptable regulation and a ripple free supply and yet uses very few components.

The transformer used is a readily available 12V-0-12V, 2A type connected at the end terminals for 24V, 1A output. After rectification and filtering, a constant reference voltage is obtained by the 24V, 500mW zener diode.

The pots used for voltage variation are 23mm carbon-film linear type and for current limit 10 ohm, 1w wirewound type is used. All the components can be connected on a group board. Necessary heatsinks should be provided for both SL100 and 2N3055.

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LM317 Calculator or LM317 Toolkit Software

Program to calculate the resistance at a LM317 / LM117.

LM317 toolkit software is completely free, fully functional and easy to use. It runs under Microsoft Windows NT, 2000, XP and Vista.

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