Regulated Power Supply Archives - Power Supply Circuits PSU, Battery Charger, Inverter Sun, 15 Apr 2018 06:37:32 +0000 en-US hourly 1 https://i0.wp.com/powersupply33.com/wp-content/uploads/2022/09/ms-icon-144x144-1.png?fit=32%2C32&ssl=1 Regulated Power Supply Archives - Power Supply Circuits 32 32 103689082 Auto Switch-Off Power Supply (Variable Output 3.7V to 8.7V) https://powersupply33.com/auto-switch-off-power-supply-variable-output-3-7v-to-8-7v.html Wed, 25 Apr 2018 04:54:08 +0000 http://powersupply33.com/?p=2407 Here is the auto switch-off power supply which will turn off itself when there is no load on the output. The output voltage can […]

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]]> Circuit Diagram of Auto Switch-Off Power Supply
Here is the auto switch-off power supply which will turn off itself when there is no load on the output. The output voltage can be vary from 3.7V upto 8.7V. Although this circuit uses fixed-voltage regulator LM7805, but its output voltage is adjustable, thanks to a potentiometer installed between common terminal of regulator IC and ground. For every 100-ohm increment in the in-circuit value of the resistance of potentiometer VR1, the output voltage increases by 1 volt. Thus, the output varies from 3.7V to 8.7V (taking into account 1.3-volt drop across diodes D1 and D2).

Another important feature of this auto switch-off power supply is that it switches itself off when no load is connected across its output terminals. This is achieved with the help of transistors T1 and T2, diodes D1 and D2, and capacitor C2. When a load is connected at the output, potential drop across diodes D1 and D2 (approximately 1.3V) is sufficient for transistors T2 and T1 to conduct. As a result, the relay gets energised and remains in that state as long as the load remains connected. At the same time, capacitor C2 gets charged to around 7-8 volt potential through transistor T2. But when the load is disconnected, transistor T2 is cut off. However, capacitor C2 is still charged and it starts discharging through base of transistor T1. After some time (which is basically determined by value of C2), relay RL1 is de-energised, which switches off the mains input to primary of transformer X1. To resume the power again, switch S1 should be pressed momentarily. Higher the value of capacitor C2, more will be the delay in switching off the power supply on disconnection of the load, and vice versa.

Though in the prototype a transformer with a secondary voltage of 12V-0V, 250mA was used, it can nevertheless be changed as per user’s requirement (up to 30V maximum. and 1-ampere current rating). For drawing more than 300mA current, the regulator IC must be fitted with a small heat sink over a mica insulator. When the transformer?s secondary voltage increases beyond 12 volts (RMS), potentiometer VR1 must be redimensioned. Also, the relay voltage rating should be redetermined. (electronics4u magz)

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]]> 2407 15V 1A Regulated Symmetrical Power Supply https://powersupply33.com/15v-1a-regulated-symmetrical-power-supply.html Sun, 26 Mar 2017 11:40:57 +0000 http://powersupply33.com/?p=2376 This is the easy built 15V 1A regulated symmetrical power supply capable to deliver stabilized voltage of +15V DC and -15VDC. The maximum current […]

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]]> 15V 1A Symmetrical Power Supply Circuit Schematic

This is the easy built 15V 1A regulated symmetrical power supply capable to deliver stabilized voltage of +15V DC and -15VDC. The maximum current output is about 1 ampere up to 1.5 ampere refer to the datasheet. The circuit uses IC regulator LM7815 for positive voltage and LM7915 for negative voltage. To obtain different voltage output, just replace the IC regulator LM78xx and LM79xx, the xx code is the output DC voltage value.

Component List

  • Transformer: 1A center tap transformer with output 15 0 15 : 1
  • Diode 1A (1N4006 or 1N4007): 4
  • Electrolytic capacitor 4700uf/25V: 2
  • Nonpolar capacitor 1uF (100nF): 2
  • IC Regulator LM7815: 1
  • IC Regulator LM7915: 1

Notes:

  • You may add a fuse between mains to the transformer
  • You may add a LED indicator on the positive output and ground (series joint with resistor 470 ohm)

15V 1A Regulated Symmetrical Power Supply PCB Layout Design

15V 1A Symmetrical Power Supply PCB Layout Design

15V 1A Symmetrical Power Supply Component Layout

That’s all, goodluck

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]]> 2376 12V / 3A Regulated Power Supply https://powersupply33.com/12v-3a-regulated-power-supply.html Mon, 21 Nov 2016 03:36:44 +0000 http://powersupply33.com/?p=2366 Here we provide a powerful 12V / 3A regulated power supply circuit. Of course the circuit provides a 12V regulated power supply with output […]

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]]> 12V / 3A Regulated Power Supply Scheme Diagram

Here we provide a powerful 12V / 3A regulated power supply circuit. Of course the circuit provides a 12V regulated power supply with output current up to 3 amperes. It is specially designed for use with 2m handheld rigs with linear power amplifier and CB portable QRP rigs.

The power supply circuit uses monolithic IC CA3085 voltage regulator in 8-lead TO-5 package. Its salient features include good load and line regulation, output current up to 100mA (which can be increased to several amperes with additional pass transistors), output short-circuit protection, and lower input voltage.

A low power dissipation is achieved by driving external series-pass transistor 2N4241 (T1) from pin 2 of CA3085. Normal output pin 8 is returned to ground via diodes D3 and D4 to ensure error amplification operation in the linear region. Ripple rejection is approximately 50 dB on no load and 35 dB on full load.

A 2x2x2.5cm aluminium heat sink fastened onto a 1.5mm blackened aluminium sheet of 12.5cm2 area on 2N4241 helps the 12V / 3A regulated power supply circuit in dissipating heat without exceeding maximum device ratings.

CA3085 can dissipate up to 650mW power in free air, without any heat sink. AFCO-make C-05-4 heat sink is suitable for this IC. An improper heat sink may cause device junction temperature to exceed the limit, resulting in progressive deterioration of the device.

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]]> 2366 Bench Power Supply Adjustable 1.25V-15V and Fix 5V https://powersupply33.com/bench-power-supply-adjustable-1-25v-15v-and-fix-5v.html Sun, 06 Sep 2015 02:32:03 +0000 http://powersupply33.com/?p=2293 This is bench Power Supply give you three types of voltage output that are adjustable 1.25V-15V / 1A positive voltage, adjustable 1.25V-15V / 1A […]

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