LM7912 | Electronic Project Circuits

Posts Tagged ‘LM7912’

12V 20Amp Power Supply by IC 7912 + 2N3055

Here is 12 volt power supply 20A , USE LM7912 and 2N3055 .
It easy circuit , Low cost. see detail more in image.

This power supply is the result of the use of components at hand (junk box). The core of the project is a number of 2N3055 transistors and a transformer with a 16 volt 18 amp secondary winding.

As it is constructed using the parts I had available at the time it may not be the most cost effective design if all parts are purchased new.
Circuit
Rather than use a more conventional arrangement with a positive supply it was easier to use a negative supply and make use of a 7912 negative regulator as the voltage control. Then by using available NPN transistors to boost output, an output up to 20 amps can be obtained at 12 volts.

Read More Source:http://radarclub.tripod.com/Homebrew.htm

Be the first to comment - What do you think? Posted by admin - October 22, 2007 at 12:00 am

Categories: High current power supply, Power supply Tags: 12 volt power supply, 24v to 12v converter circuit, High current power supply, LM7912

13.8V 20A Stabilized regulator by 7912,2N3055

This is circuit Power Supply regulator 13.8V 20A.
Use part Electronics IC 7912 and Transistor 2N3055 x 6.
It is High Current power supply and easy circuit.

The starting problem was to recycle some things: chassis, transfomer, heat sinks etc: what to do?
A power supply, of course !

This time I’ve stabilized the negative side using 6 cheap 2N3055 with collector directly mounted on the chassis.
TRANSFORMER
My transformer was 220/19V;
you can calculate the power it can give by the core dimension, but I’ve preferred use a practical way:
I’ve used a 100 meter / 1,5 mm wire and measured its resistance; it was about 1,1 ohm; so I’ve connected it to the output of the transformer; after about 30 seconds the transformer was still cold; well, due to the Ohm’s law, the trasformer was able to supply at least 19 / 1,1 = 15-18 ampere: OK, it was good.

RECTIFIER BRIDGE

Rectifier bridge’s diode usually see a voltage of Vout x 2,828, so it’s better to use one with a PIV 3 or 4 time bigger than the output voltage (19×3=57V);
same words for the current: a 50Ampere bridge has been used.
At first I’ve used a 25A one and infact after few test it has broken.

CAPACITOR FILTER

For a bridge rectifier you must use the following formula to calcule the amount of needed capacitance:

C= 1,8 x (I / VR)

where I is the max current and VR is the max ripple;
if a stabilizer follows the capacitors (as here), then you can use a value 40% lower than the calculated one; in my power supply I’ve used 2x 22000 microF / 40VL.
The working voltage of capacitor should be at least 40 % bigger than the output voltage.

STABILIZER IC
I’ve used a LM7912.
Read More Source:http://www.qsl.net/iz7ath/web/02_brew/20_ps7912/index.htm

Be the first to comment - What do you think? Posted by admin - October 1, 2007 at 10:49 pm

Categories: High current power supply, Power supply Tags: 13.8V power supply, High current power supply, LM7912, stabilized voltage regulator

Power Regulator +12V_-12V by 7812 , 7912

Here is circuit Power Regulator +12V_-12V .
Use IC -LM7812 for +12V and IC LM7912 for -12V.
This is circuit for Preamplifier play nice Music.
Detail See in circuit.