Regulator for Three-Phase Generator

This regulator was designed for use with a  generator with a higher output voltage. This  type of generator can be found on some boats  and on vehicles for the emergency services.  They are really just an adapted version of the  standard alternator normally found in cars.  The field winding is connected to the 12 V  (or 24 V) battery supply, whereas the generator winding is configured for the AC grid  voltage (230 V or 115 V). This AC voltage now  has to be kept stable via the 12 V field winding. Although it’s perfectly possible to use a  switching regulator for this, we deliberately  chose to use the old and trusted 723.

Circuit diagram :

Regulator for Three-Phase Generator Circuit Diagram

The generator is a three-phase type, with the  field winding rated for 12 VDC. The output voltage of the generator depends on its revs  and the current through the field winding.  Since the output voltage is relatively high, it  is fed via opto-couplers to the 723, which is  used in a standard configuration.  The output is fed via driver T1 to two  2N3055’s, connected in parallel, which sup-ply the current to the field winding. In the prototype we used TLP620 opto-couplers. These are suitable for use with alternating voltages because they have two anti-parallel LEDs at the input. The regulation works  quite well with these, with the output volt-age staying within a small range across a wide  range of revs.

However, the sensitivity of the two internal  LEDs can differ in this type of opto-coupler,  since it’s not always possible to ensure during  the manufacturing process that the distance  between each LED and the phototransistor is  exactly the same. For a more precise regulation it would be better to use two individual  opto-couplers per phase, with the inputs connected in anti-parallel and the outputs connected in parallel.

In order to ensure that there is sufficient isolation between the primary and secondary side  you should make a cutout in the PCB underneath the middle of each opto-coupler. Instead of a BD136 for T1 you could also use  a TIP32 or something similar. For T2 and T3  it’s better to use a type with a plastic casing,  rather than a TO3 case.

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Monolithic Step-Down Switching Regulator

L4962 is a monolithic step-down  switching regulator. It provides  output voltage of 5.1V to maxi-mum 40V, delivering current up to  1.2A to 1.5A, depending on the type  and package. The theoretical internal  functions are almost the same. The  heart  of  the  device  is  the  regulation  loop  consisting  of  a  saw  tooth  oscillator, error amplifier, comparator and  source-sink output stage.

Circuit diagram :

 Fig. 1: Circuit of switching regulator

An error signal is produced by  comparing  the  output  voltage  with  a precise 5.1 volt on chip reference  (which is zener zap trimmed to ±2  per cent). This error signal is then  compared  with  the  saw  tooth  signal  to generate the fixed frequency pulse  width  modulated  pulses  which  drive the output stage.

Fig. 1 shows circuit diagram of  the regulator. The gain and frequency  of the loop can be set by RC network  connected to IC pin 11. When the loop  is  closed  directly  by  connecting  the  supply output to the feedback input  IC pin 10, an output voltage 5.1 volt is  produced. Higher output voltages are  obtained by inserting a voltage divider  in this feedback path. the outputs over current errors generated  at  the  on  switch  are  prevented  by  the  self-start  function.  The  error  amplifier  output is initially  clamped  by  the  external  capacitor ‘Css’ of pin15,  and  is  allowed  to  rise  linearly  as  this  capacitor  is  charged  by  a  constant  current  source.

Output overload protection is pro-vided in the from of a current limiter.  When the load current exceeds a preset  threshold, this comparator sets a flip-flop, which disables the output stage  and discharges the soft start capacitor. Another internal comparator resets  the flip-flop when the voltage across the soft capacitor C3 falls  to 0.4V. The output is thus  re-enabled  and  the  volt-age  rises  under  the  control of soft start network.  If overload condition is  still  present,  the  limiter  will  trigger  again  when  the  threshold  current  is  reached.  The  average  short-circuit is limited to a  safe value by the dead time introduced  in the soft start network. The thermal  overload circuit disables circuit operation when the junction temperature is  about 150°C and has hysteresis to  prevent instability. Frequency is about  100 KHz with parallel RC network connected to this terminal.

Assemble the circuit on a general-purpose PCB by using two connectors one  for  the  input  and  the  other for the output. You can also use  a  DC-DC  converter  circuit  in  place  of  the  linear  regulator  to  avoid  the  use  of transformer and also to reduce dissipation. Finally, short-circuit protection is provided for all of the auxiliary  outputs by clips, internal current limiter and thermal protection circuit.  It is a ferrite torroid core T-18  with a small 20 turns of 27 SWG enameled copper wire.

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1.5 - 35 Volt DC Regulated Power Supply

Here is the circuit diagram of regulated power supply. It is a small power supply that provides a regulated voltage, adjustable between 1.5 and 35 volts at 1 ampere. This circuit is ready to use, you just need to add a suitable transformer. This circuit is thermal overload protected because the current limiter and thermal overload protection are included in the IC.

Picture of the circuit:

1A Regulated Power Supply Circuit Schematic

Circuit diagram:

1A Regulated Power Supply Circuit Diagram

Transformer selection chart:

Transformer selection Guide-Table For Power Supply

Parts:
IC = LM317
P1 = 4.7K
R1 = 120R
C1 = 100nF - 63V
C2 = 1uF - 35V
C3 = 10uF - 35V
C4 = 2200uF - 35V
D1-D4 = 1N4007

Features:

• Just add a suitable transformer (see table)
• Great to power your projects and save money on batteries
• Suitable as an adjustable power supply for experiments
• Control DC motors, low voltage light bulbs, …

Specifications :

• Preset any voltage between 1.5 and 35V
• Very low ripple (80dB rejection)
• Short-circuit, thermal and overload protection
• Max input voltage : 28VAC or 40VDC
• Max dissipation : 15W (with heatsink)
• Dimensions : 52x52mm (2.1” x 2.1”)

Technical Specifications

• Input Voltage = 40Vdc max Transformer
• Output Voltage = 1.5V to 35Vdc
• Output Current = 1.5 Amps max.
• Power Dissipation = 15W max (cooled)

Note:

• It has not to be cooled if used for small powers. 28 Volt AC max is allowed for the input voltage.

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Ultra Low Drop Linear Regulator

The circuit is a MOSFET based linear voltage regulator with a voltage drop of as low as 60 mV at 1 ampere. Drop of a fewer millivolts is possible with better MOSFETs having lower  RDS(on)  resistance. 

The circuit in Fig.1 uses 15V-0-15V secondary output from a step-down transformer and employs an n-channel MOSFET IRF540 to get the regulated 12V output from DC input, which could be as low as 12.06V. The gate drive voltage required for the MOSFET is generated using a voltage doubler circuit consisting of diodes D1 and D2 and capacitors C1 and C4. To turn the MOSFET fully on, the gate terminal should be around 10V above the source terminal which is connected to the output here. The voltage doubler feeds this voltage to the gate through resistor R1. Adjustable shunt regulator TL431 (IC2) is used here as an error amplifier, and it dynamically adjusts the gate voltage to maintain the regulation at the output.
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Ultra Low Drop Linear Regulator Circuit Diagram 
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Circuit Fig.1

With adequate heatsink for the MOSFET, the circuit can provide up to 3A output at slightly elevated minimum voltage drop. Trimpot VR1 in the circuit is used for fine adjustment of the output voltage. Combination of capacitor C5 and resistor R2 provides error-amplifier compensation. 

The circuit is provided with a short-circuit crow-bar protection to guard the components against over stress during accidental short at the output. This crow-bar protection will work as follows: Under normal working conditions, the voltage across capacitor C3 will be 6.3V and diode D5 will be in the off state since it will be reverse-biased with the output voltage of 12V. However, during output short-circuit condition, the output will momentarily drop, causing D5 to conduct and the opto-triac MOC3011 (IC1) will get triggered, pulling down the gate voltage to ground, and thus limiting the output current. The circuit will remain latched in this state, and input voltage has to be switched off to reset the circuit. 

Circuit Fig.2

The circuit shown in Fig.2 follows a similar scheme. It can be utilised when the regulator has to work from a DC rail in place of 15V-0-15V AC supply. The gate voltage here is generated using an LM555 charge pump circuit as follows: 

When 555 output is low, capacitor C2 will get charged through diode D1 to the input voltage. In the next half cycle, when the 555 output goes high, capacitor C3 will get charged to almost double the input voltage. The rest of the circuit works in a similar fashion as the circuit of Fig. 1. 

The above circuits will help reduce power-loss by allowing to keep input voltage range to the regulator low during initial design or even in existing circuits. This will keep the output regulated with relatively low input voltage compared to the conventional regulators. 

The minimum voltage drop can be further reduced using low RDS(on) MOSFETs or by paralleling them.

Source by : www.circuitsproject.com

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New Zener Diode Circuit Diagram

Here we used the 12-0-12 step-down 500mA power transformer. The output of the transformer is supply to the bridge rectifier made of D2 , D3, D4, D5 which is use to convert the Ac supply to the DC supply. Capacitor C1 is used as a filter the DC output. We used  470 μF capacitor  but you can used any. More the value of capacitor more pure DC can be obtained. Resistor R2 of 2.2K is used as bleeder. Here you can see the transistor T1 [BC147B] and transistor T2 [SL100] are use for regulator compressor.

The DC output is fed to these transistors. T1 acts as a series pass driver or a current regulator. Base bias for transistor T1 is achieved from the supply through resistor  R3 of 680 ohms  as resistor R2 of  10k is a base bleeder and capacitor C2 1 μF  filters base potential. When the test probe is fully open with no zener connected, the base potential of transistor T1 is around 32V that is across resistor R4 or capacitor C2.

New Zener Diode Circuit Diagram 

Transistor T1 [BC147B] provides the base potential for transistor T2 [SL100] which acts as a series pass regulator, providing the net DC voltage equivalent to T1 base potential which is fed to the voltmeter.

Now, the voltmeter reads around 30V with no zener diode connected across the probe. When a zener  diode is connected across the test probe, the base potential of transistor T1 falls to zener diode breakdown voltage. With this, the base potentials for transistor T2 and transistor T1 become equal. The meter now shows the actual zener voltage. An adjustment of 0.6 V can be done on the meter scale by shifting the needle with zero adjustment screw on the meter.

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Rotative Speed Regulator Borer, Driller Controller

This rotative speed regulator circuit schematic allows to control the holing speed of your borer or driller machine. This project is based on the fact that if the load grows, the voltage decrease and current increase. Use this circuit to control the speed of revolutions of your drilling mill or bench drill.

Driller controller circuit schematic

 

Source By :www.circuitsproject.com

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