Electronic Circuits and Diagram-Electronics Projects and Design

Description. This dual power supply is based on the L165 power operational amplifier from SGS-Thomson Micro electronics. The IC L165 can easily deliver up to 3.5A of current (internally limited). The IC is available in Pentawatt package and is very suitable for power supply applications like this. Here the L165 is wired as a voltage amplifier which amplifies the voltage available at the junction between R1 and R2.The output voltage will be always half of the input voltage (Vin).For example if you give 24V at the input (Vin), you will get a +12V/-12 V at the output.C2 is the input…

Description. This 13V/5A power supply is based on the famous LM338 IC from the ST Microelectronics. The IC has time dependent current limiting, thermal regulation and is available in 3 lead transistor package. The IC can easily supply well over 5A at an output voltage range between 1.2V and 30V. In this circuit the output voltage is determined by the two resistors R1 and R2.The output voltage can be varied by adjusting the R2.Diodes D2 and D3 are protection diodes. Capacitors C1 and C5 are filter capacitors while C2 and C3 are decoupling capacitors. Circuit diagram. Notes. Transformer T1 can…

Description. This is the circuit diagram of a 3A adjustable power supply using IC LM350K.. LM350K is a very rugged voltage regulator IC with features like thermal regulation, short circuit protection etc. This circuit is designed as per the application notes in the data sheet and was found to be working very fine.This circuit has improved ripple rejection and better stability compared to the elementary voltage regulator using the same IC. The output voltage can be adjusted by using the POT R2.By adjusting R2 the output voltage can be varied between 1.2V and 25V.The diode D2 discharges capacitor C2 when…

Description. Here is the circuit diagram of a fuse that has an automatic status indicator. This circuit can be added to circuit that operates from 12V DC. As long as the fuse is intact, the LED D3 will glow continuously and when the fuse blows off the LED will start and continue blinking. The first part of the circuit includes an astable multivibrator built around transistors Q1 and Q2.The output of the multivibrator is coupled to the base of Q3 via diode D2.When the fuse is intact the base of Q3 will be pulled to a positive voltage by the…

Description. This 40V dual power supply circuit was designed in response to a request made by Michael from Philippines. His application is to power the 150 Watt amplifier circuit published here. I think this power supply design is adequate for the purpose. The transformer T1 steps down the mains voltage, bridge D1 performs the rectification, C1 and C2 does the job of filtering.C3 and C4 are decoupling capacitors. Circuit diagram with Parts list. Notes. The T1 must be a 230V primary, 30-0-30V secondary, 200VA transformer. All capacitors must be rated at least 63V. C3 and C4 are polyester capacitors. If…

Description. The circuit given below is of a simple audio amplifier that can deliver 12W to an 8 Ohm speaker. Op amp IC TL081 is used as the preamplifier here. Actually any opamp with matching power supply ratings can be used instead of TL081.Transistors Q1 and Q2 (TIP125 and TIP120) comprises the power amplifier stage. Output is taken from the collector junction of two transistors. Circuit diagram. Notes. The circuit can be assembled on a Vero board. Heat sinks are recommended for the transistors. A +15V/-15V dual DC power supply can be used to power the circuit. It is better…

Description. The circuit given here is of a regulated dual power supply that provides +12V and -12V from the AC mains. A power supply like this is a very essential tool on the work bench of an electronic hobbyist. The transformer T1 steps down the AC mains voltage and diodes D1, D2, D3 and D4 does the job of rectification. Capacitors C1 and C2 does the job of filtering.C3, C4, C7and C8 are decoupling capacitors. IC 7812 and 7912 are used for the purpose of voltage regulation in which the former is a positive 12V regulator and later is a…

Description. This 1.3V power supply can be used as replacement for the 1.3V Mercury Cell in any circuit. When the input 5V is given to the circuit, the  voltage drop across  zener diode D1 will be around 2V.The diode D2 will drop a 0.7 V from the 2V volt and the remaining 1.3V will be available at the output. The Resistor R1 limits the current through Zener diode Circuit diagram with Parts list. Notes. The circuit can be assembled on a general purpose board. This power supply is suitable for devices like digital multimeters, digital clocks, digital thermometers etc. The…

Description. Here is the circuit diagram of a simple soft start power supply using the well known IC L200.The L200 is a monolithic IC that can be used for voltage and current regulation. The built-in features such as thermal shut down, over current protection and input over voltage protection makes this IC nearly indestructible. When the power supply to the circuit is switched ON, the capacitor C3 starts to charge through resistor R3.The internal comparator pin (pin2) of the IC is connected to the positive lead of C3.When capacitor C3 is charging the voltage at the internal comparator pin also…

Description. Here is the circuit diagram of a simple soft start power supply using the well known voltage regulator IC LM317.Here the IC is wired in soft start mode in which the output of the IC gradually increases to the desired output voltage .When the input voltage is given to the IC , the capacitor C1 starts to charge and the current from the adjust pin (pin2) of the IC increases.The output voltage of the IC at any time is proportional to this adjust current(I adj).So the output of the IC slowly increases from 0 to 15V which is set…