Research Cell
Mechanical and Electronics Related Information and DIY Projects

7812 Pin and Circuit Diagram

7812 is a famous IC that is being widely used in 12V voltage regulator circuits. Truly speaking it is a complete standalone voltage regulator. We only need to use two capacitors, one on the input and the second one on the output of 7812. These capacitors will help us to achieve clean voltage output. You can even skip these capacitors in case of nonsensitive load.

You should mount a good heatsink plate with your 7812. This will help you in getting the full 1.5A current from your 7812. Thanks to the transistor-like shape of 7812 which makes it easy to mount on a heatsink plate. 7812 has built-in overheat and short circuit protection which makes it a good choice for making regulated power supplies.

7812 Variants

In electronics markets, 7812 is sold under various names such as 7812a, 7812act, 7812t, and lm7812. All of them are almost identical with little to no differences at all. 7812 input voltage range is 14V to 35V. Exceeding the voltage range may damage the IC. Given bellow is a 7812 pin diagram to make the pinout connections clear in case you want to do some experiments.

If you hold upside down (pins up) and the IC number is facing you then the left pin will be the voltage regulator output, the center pin will be ground and the right pin will be the voltage input pin. From my experience, the maximum safe current you can get from one 7812 IC is 1A. If you need more power then there are a few ways to do so.

7812 in Parallel

We can use more than one 7812 in parallel to get more than 1A current but the output voltage of each 7812 can slightly vary resulting in an unbalanced load on all of them. This can result in load balancing issues and can damage the IC carrying most current. However, there is a way to overcome this problem. I have bellowed a schematic diagram in which two 7812 ICs are attached and both of them are carrying an almost equal load. At least the current difference is not too much to damage any IC.

7812 in parallel circuit diagram
7812 in parallel circuit diagram

Please note that in this circuit diagram, I have used resistors for load balancing purposes so the output of this voltage regulator circuit may be slightly inaccurate. Both resistors should be a minimum of 15 Watt or above. If you don’t find such resistors in your area then you can make them using 32 gauge or thinner copper wire. This parallel 7812 circuit will provide 12V and approximately 2A current. You can increase the number of 7812 but each additional 7812 will require a resistor on its output.
Following is the link to a simple but complete power supply circuit diagram developed using 7812.

Voltage Regulator Circuit

  1. Adelusi Tosin says:

    sir i used ic 7812 to charge my 12v 62ah battery through solar panel as the source of power, yet it not charge the battery. Sir, is there any way that i can use to charge this battery throuhg solar cell of 120v dc. Thanks.
    Pleased sir kindly anwser to my mail @adelusioluwatosin01@gmail.com.

  2. Mina says:

    Thanks, very useful!
    Can I use 24 volt as input, but with a resistor before inserting 24 volt to 7812 to acheive a regulated 12 volt?

  3. CHARY says:

    i want to know how to connect lm7812 to 18volts adaptor

  4. Sanjeev says:

    I want to use LM7812 as 12v LED homelight driver. Can I?

  5. Elektrolord says:

    Before you can use it with 18v you will need to reduce the the voltage by dividing the voltage.

  6. omid says:

    by notice to (W=RI2) and maximum current(1A)
    Why does the resistors must be 15 watt ?
    Thank you

  7. Sagar Awachat says:

    Dear Sir, Can I use this IC 7812 for input 12 volt 42 Ah DC battery ?

  8. Frederick Gica says:

    I am using step down transformer, 220V in and out is 12v 0 12v and 3ampere as its specifications. Im gonna need a regulated 12v output with still 3ampere current. Can I obtain the same using 7812 regulator when it says it has an output of 12v , 1ampere? If not, how can I obtain 3ampere output?
    Thanks

  9. Pawan says:

    What’s work 7805 ic

  10. Audentes says:

    If you want to charge a 12VDC battery you need to supply a higher voltage. Typically 13 to 15 VDC. Think of this as a balance scale. You want to transfer, water, for example, from one side to the other. If the levels are equal, no water will transfer. Hence, if a 12 volt battery is on one side, then 12 volts on the other will result in no transfer to the battery.

  11. Jitendra says:

    Hi, i have lm317t but it shows decrese in voltage and current when controlled on 12v . Please tell me if this can happen in this ic?

  12. Leave a Reply

    Your email address will not be published.