7805 Regulator | Electronic Project Circuits

Posts Tagged ‘7805 regulator’

Dual Variable Regulator power supply 5-25V by LM7805,LM7905

When you want Dual power supply Variable Regulator be simple. I begs for to advise this circuit, because use the integrated circuit LM7805 and IC 7905. Make have Voltage +5V to +25V and -5V to -25V unless. VR1 for Adjustable + Volt output,VR2 for adjustable -volt output. Still pay current get about 1A enough with general usability. The important factor is you should use Transformer at enough size doesn’t lower 2A and IC all stick let off the heat with. The detail is other see in circuit picture better sir.

Be the first to comment - What do you think? Posted by admin - October 30, 2008 at 5:58 am

Categories: Power supply, Variable Regulator Tags: 7805 regulator, dual power supply, IC 7905, variable voltage regulator

12V to 5V 3A DC converter step down Regulator

Today I has 12V to 5V 3A DC converter step down Regulator circuit come to deposit. In sometimes friends have power supply 12V 3A , but want Voltage 5V 3A for digital Circuit. This circuit can meet the demand of friends get , by it uses normal electronic part and have 7805 integrated circuits perform to control Voltage 5V Regulate alone it gives current get just 1A. then must have an assistant is transistor MJ2955 perform enlarge current tallly go up be 3A besides. When be born over load or shot circuit as a result still have LED1 bright warn with. And still make Q2 – BD140 work cause Q3 – MJ2955 stop work with. The circuit then safe have no a problem friends may like this circuit. Because the equipment seeks easy , build not difficult too yes.

Be the first to comment - What do you think? Posted by admin - October 2, 2008 at 8:02 am

Categories: Power supply Tags: 5 volt regulator, 7805 regulator, dc converter step down voltage

Battery Backup Supply with IC 7812 and 7805

Here is circuit 9V power supply regulator with battery 12V backup system.
Use IC 7812 and 7805 control voltage output by R3 1K output 9V 1A max.

This is a 9V power supply which will work even on power failure. It uses a rechargeable battery and regulators. A transformer with 15-0-15 AC volts output is required. In the first regulator U1 the output is lifted up by 1.4V and in the second regulator U2 by a resistor divider. In the second regulator the voltage across resistor R3 is 5V, so the current is 5V / 1K = 5mA this adds to the quiescent current of 5mA from the regulators ground terminal and flows into the resistors R1 and R2 in parallel which form 404 ohms, 10mA thru 404 ohms is 4V. So the output will be 5 + 4 = 9V. Note that the charge and discharge paths of the battery are separated with diodes.

Source:http://schematics.blogspot.com/2004/10/battery-backup-supply.html
Thank you.