Current Limit | Electronic Project Circuits

Posts Tagged ‘current limit’

Simple Regulator Circuits with current limit by FET

Here the circuit has been modified to provide current limiting to reduce the output voltage if too much current is demanded. This will reduct the possibility of damaging equipment by drawing excessive current. All component values not marked are the same as in the previous circuits. R1 = 0.7 / Amperes.

* R1 = 10 ohms for 60 mA
* R1 = 7 ohms for 100 mA
* R1 = 2.5 ohms for 300 mA
* R1 = 1 ohm for 700 mA
* R1 = 0.7 ohms for 1 A
* R1 = 0.25 ohms for 3 A

Read More Source:http://web.telia.com/~u85920178/begin/psu-1.htm
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Categories: Power supply Tags: current limit, dc voltage regulator, power supply

Current-Limit Switch Is Digitally Programmable

Current-limit switches are virtually ubiquitous in system controls. They provide a safe means for regulating the current delivered to a load circuit. The switches allow the load current to increase to a programmed limit but no higher. This application note illustrates the implementation of a digitally programmable current-limit switch using MAX890L a current-limited, high-side P-channel switch and MAX5160 digital potentiometer

Variable DC Power Supply Voltage range 0.7 – 24V, Current limiting range 50mA – 2A

Voltage range: 0.7 – 24V

Current limiting range: 50mA – 2A

Device purpose:
A Variable DC Power Supply is one of the most useful tools on the electronics hobbyist’s workbench. This circuit is not an absolute novelty, but it’s simple, reliable, “rugged” and short-proof, featuring variable voltage up to 24V and variable current limiting up to 2A. It’s well suited to supply the circuits shown in this website. You can adapt it to your own requirements as explained in the notes below.
Parts:
P1____________500R Linear Potentiometer
P2_____________10K Log. Potentiometer
R1,R2___________2K2 1/2W Resistors
R3____________330R 1/4W Resistor
R4____________150R 1/4W Resistor
R5______________1R 5W Resistor
C1___________3300Î…F 35V Electrolytic Capacitor (see Notes)
C2______________1Î…F 63V Polyester Capacitor
D1,D2________1N5402 200V 3A Diodes
D3_____________5mm. Red LED
Q1____________BC182 50V 100mA NPN Transistor
Q2____________BD139 80V 1.5A NPN Transistor
Q3____________BC212 50V 100mA PNP Transistor
Q4 __________2N3055 60V 15A NPN Transistor
T1_____________220V Primary, 36V Center-tapped Secondary 50VA Mains transformer (see Notes)
PL1____________Male Mains plug
SW1____________SPST Mains switch
Device purpose:
A Variable DC Power Supply is one of the most useful tools on the electronics hobbyist’s workbench. This circuit is not an absolute novelty, but it’s simple, reliable, “rugged” and short-proof, featuring variable voltage up to 24V and variable current limiting up to 2A. It’s well suited to supply the circuits shown in this website. You can adapt it to your own requirements as explained in the notes below.

Notes:
P1 sets the maximum output current you want to be delivered by the power supply at a given output voltage.
P2 sets the output voltage and must be a logarithmic taper type, in order to obtain a more linear scale voltage indication.
You can choose the Transformer on the grounds of maximum voltage and current output needed.
Best choices are: 36, 40 or 48V center-tapped and 50, 75, 80 or 100VA.
Capacitor C1 can be 2200 to 6800uF, 35 to 50V.
Q4 must be mounted on a good heatsink in order to withstand sustained output short-circuit.
In some cases the rear panel of the metal box in which you will enclose the circuit can do the job.
The 2N3055 transistor (Q4) can be replaced with the slightly less powerful TIP3055 type.
Excellent quality-price ratio: enjoy!
source: RED Free Circuit Designs