Chosing and finding a device

I am trying to develop a circuit using an ESP32, a 1528-1462-ND Microsd card, and a Feiyang max98357 amp output board. All these devices will operate at 3.3 volts. I would like to power this circuit using 12 v DC. I would like to include a bridge diode to insure proper polarity for the input. I am stuck, right now, finding parts for the power supply. I am looking at a circuit I found that uses a LM7805 that seems like it should work except it is 5v. I don’t seem to be able to find a similar part that will put out 3.3 V

Am I on the right track?
If so, can someone tell me the part number and maybe explain how the selection process works so I can find a part for myself?

Here’s the circuit I found:

Will a heat sing be necessary for this device?

Hello Bart,

Yes. You seem to be on the right track. Here is a part number LT1086CT-3.3#PBF-ND for 3.3 volt regulator. Here are some more options :

You can just search voltage regulator on the website. Click on the catgory. Here is what you will see:

It is overwhelming. Usually I say to go to the most important box and select what you need the most. The once you do that the apply all will highlight. Do one box at a time to filter. Apply all before moving to the next box. Once you start eliminating options by applying filters the choices go down alot. Skip over the boxes you do not know. If you do the one box at a time and lose all options. At least you know what you did to lose the choices. I also recommend to click in stock so you only get stocking options.

Thank you for the very quick reply!
Am I correct in assuming the capacitors are electrolytic?

And, can I put a bridge diode between the input and this device? I understand it will drop the input by 1.4V Is that correct?

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Yes . The voltage drop would be the 1.4 volts . Though double check the data sheet. Yes, The values for the capacitors show that hey most likely would be electrolytic.

Again. Thanks so much for your reply. I’m obviously in way over my head. But it’s fun!

I find I usually need a heat sink when drawing more than about 0.1mA from a linear regulator that is dropping 7 volts (12 - 1.4 - 3.3) or more. You can tell if you need a heat sink by holding the metal tab at power on, if it gets uncomfortable to hold, you need a heat sink.

You should consider a three terminal switching regulator module like this:

They were designed specifically to replace the old 3 terminal linear regulators like the 78xx series. They don’t need a heat sink, have a wider input voltage range and save a lot of electricity. In this application a linear regulator will use a lot more power than a switching regulator.

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That looks like what I want! I ordered a couple of them. We’ll see how they work out. Thank you!

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