Adjustable Power Supply Using by LM317


Adjustable Power Supply Circuit Diagram

Power Supply Circuit Diagram
For the LM317:
  • R2 = (192 x Vout) - 240, where R2 in ohms, Vout is in volts and must be at between 1.2 V and 35 V.
  • Vin should be at least 2.5V greater than Vout. Select a wall adapter with a voltage at least 2.5 V greater than your regulated output at full load
  •  Maximum output current is 1 A. Use proper heatsink for LM317 if it has to dissipate more than 1W.
  • The tab of the LM317 is connected to the center pin.
Equation for calculating the output voltage when R1 and R2 are known:

 Vout = 1.25V * (1 + R2/R1) + Iadj * R2

Where Iadj is typically in the range of 50 microamperes.



Comments

Post a Comment

Popular posts from this blog

Build your own programmable power supply with TL431

Image
TL431 and LM431 are relatively low-noise, stable and low-cost shunt regulators. These can be used to build all sorts of power supplies including programmable power supplies, advantages of which are enormous. You can program the output voltage with simple switches. You can also program the output voltage with digital codes coming from a microcontroller (MCU) or from the printer port of a PC. You can adjust any output voltage individually with resistors or trimmer potentiometers to the required values. This article presents a programmable power supply built around TL431 (IC1) and two bipolar transistors BD139 and TIP31 (T1 and T2). The circuit also includes an inverter 7406 (IC2), nine diodes 1N4007 (D1 through D9), a 12V regulator 7812 (IC3), a 5V regulator 7805 (IC4) and a few other components. Using this circuit you can obtain around 18V, 2A unregulated output and 3V to 15V, 1A variable regulated power supply based on digitally programmable input as shown in Table I. You can also obta...
Keep reading

Echo effect with IC PT2399 schematic

Image
Effect Echo is an electronic circuit that is used to delay sound or make an echo in an audio circuit . Using a circuit of echo is easy enough , we just set on the volume, and gain and trimpot near is rate of 20 K ohm to adjust how the desired echoes. This echo circuit using ic 4558D for additional amplifier and ic PT2399 as a major component that serves to echo , or repeat the sound output on the audio system. Click image to view larger  How to use it as follows : That is initially given the output of the mic input or other equipment. Then turn down the volume, and slowly raised, setting echo effect on the trimpot 20K. If not check back for the damaged to the circuit.
Keep reading

Electronic Thermostat and Relay

Image
Here is a simple thermostat circuit that can be used to control a relay and supply power to a small space heater through the relay contacts. The relay contacts should be rated above the current requirements for the heater. Temperature changes are detected by a (1.7K @ 70F) thermistor placed in series with a 5K potentiometer which produces about 50 millivolts per degree F at the input of the LM339 voltage comparator. The two 1K resistors connected to pin 7 set the reference voltage at half the supply voltage and the hysteresis range to about 3 degrees or 150 millivolts. The hysteresis range (temperature range where the relay engages and disengages) can be adjusted with the 10K resistor between pins 1 and 7. A higher value will narrow the range. Electronic Thermostat and Relay Circuit Diagram In operation, the series resistor is adjusted so that the relay just toggles off at the desired temperature. A three degree drop in temperature should cause the relay to toggle back on and remain on...
Keep reading