Hi everyone, I am using LF RFID. I am having 30 cm read range. It is enough for me. I read the RFID's instructions. They are suggesting 7809 with big caps 1000 uF. Here:
But normally, 7809 data sheets suggest this schematic:
Which schematic should I fallow ? If I use first schematic (with 1000caps) , will it increase my read range ? and this module requires 120mA. If I use to-220 7809 without heatsink , won't be a problem right? (3V*120mA =360mW)
Something between the two. Don't miss the input capacitor - the output capacitor can be quite large, but not too large, 33uF should be plenty.
Forget the rest, such massive filtering shouldn't be needed for an RFID circuit, just using a linear regulator ought to suffice to give clean supply rail.
BTW when you say
Can you provide the link to this information? Its difficult to help when you neglect to identify the device you are talking about...
Okay, thank you. Here is a aliexpresslink this 7809 line is bottom side. directphoto
I mean they re not directly say it 100 uF . I saw the photo and I said that 
. Sorry for misrepresent.
As I said, I am having 30 cm read range, they are having 36 cm. It might be because of capacitance or 7809 I guess.
I think they are using an RFID chip and a microcontroller on the same supply, which is why they are having to massively filter out the digital hash from the supply rail with swaves of capacitors. I see 3 large tants and 6 large ceramic caps there.
Separate regulators for analog and digital components is the way to do this, especially sensitive low-level analog like microphone amps or RFID. I would use a long thin PCB with the analog stuff at one end and digital at the other, to maintain good physical separation too.
I've played with a 125kHz RFID chip (EM4095) and no special supply filtering was needed when separate from a digital device.
They may know more than you.
I have seen such filtering on several circuits. RF receivers and transmitters, microwave people detectors and the first stages of audio amplifiers.
In one case it made doesn’t work into does work. That may have been a poorly designed module, who knows if yours is or not?
You need some filtering as everyone will say. You may need more in your car. You may need all of it, not just to ensure range, but to ensure proper operation at your desired range.
Why not try it and see? And if it works without all that filtering, just make a note for later when it mysteriously isn’t working or isn’t working as well to try adding the recommended power supply condition circuitry?
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Thank you for information. I tried with 9V power regulator, without any filter (caps) and it was working. I decided to make PCB that's why I want to make power schematic for it. Thank you again.
Thank you. They are know more than me trust . I might be try this circuit but first I need to order some caps . Thank you again.
Electrolytic and tantalum capacitors don't "act like" capacitors at high frequencies so the 78xx should have a ceramic capacitor (or film, etc.) similar) on the input & output. It's OK to have an electrolytic in parallel.
A large capacitor on the output will draw "excessive" current when it's first powered-on and charging. (Once charged, the capacitors draw no current.) The 78xx is short-circuit protected so it should survive but I don't know if it's "recommended". The 1-Ohm resistors limit the current but it's still only 1-Ohm when first starting to charge and there's nothing limiting the current into the 470uF cap.
Maybe... If it gets too hot to touch, add a heatsink. 
Thank you for information. I am gonna go with 1 input ceramic caps and 1 output ceramic caps but I will try that 1000 caps circuit too. I read 7809 recommends 0.1 uF because Ceramic capacitors much larger than 0.1uF used to be expensive (in 1970) (I found on forum comment) . What is the value of caps these days. I looked the google but every schematic says 0.33 0.1, MarkT says output can be 33 uF. How can I decide that.
The other question is 1000 uF caps schematic don't have input caps. Won't it be a problem ?
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