Is a LM7805 voltage regulator possible

I have a project which is all powered by an Arduino, and have a 9v power supply to the the Vin pin, then a jumper from the 5v pin to a breadboard which has x3 5v boards attached.

I wondered if I could use a volatge regulator on the breadboard to convert the 9v to 5v and then have a wire from the breadboard to the 5v pin on the arduino.

The project is in a box with a barrel connector at the back, then GND and Vcc wires going to the arduino GND and Vin pins.

I don't want to overheat the arduinos regulator, and that is why I want to know if I could use a separate regulator.

Is this doable, and if not what is the best way to power the project and arduino.

Thanks

Yes you could use a separate regulator and it's a good idea. But I wouldn't use a linear regulator like a 7805 I'd use a 5V DC-DC converter. More efficient so less heat and less wasted power.

Steve

Thanks and googling 5v dc -dc convert gives me many choices!

What would you suggest for my situation in particular .

Thanks

If you have analog sensors then a linear regulator may be better as they are less noisy.

Yes, you absolutely want to use a "Buck" converter - such as are readily available on eBay or Aliexpress or even at much greater cost from local suppliers - to supply power to the Arduino Nano "5V" pin (and the corresponding grounds connected).

But you should not be using a solderless breadboard, rather stripboard or similar for any serious project. :astonished:

Do you mean something like this:

That looks like the sort of thing but a specification would be a lot more helpful than a pretty picture. And do you really need 10A? That's a lot of current.

Steve

No I don't need 10A.

This one then:

I see some of these buck converters have a usb port, what is the need for that. I only want something to go inside my box with the project, and drop the voltage to 5v from either 9v or 12v.

Thanks

This one might do as people have used for a Raspberry Pi:

https://www.amazon.co.uk/Power-Module-DC-DC-Supply-Converter/dp/B071ZRXKJY/ref=sr_1_3?dchild=1&keywords=12v+to+5v+buck+converter&qid=1587227588&sr=8-3#customerReviews.

avalon66:
I see some of these buck converters have a USB port, what is the need for that.

Because a lot of things use a USB connector simply for 5 V power, such as for charging mobile phones in a car - which is a common use for these "buck" converters. :grinning:

If you want to make your own DC-DC converter, the LM2596S-5 can be used.

thehardwareman:
If you want to make your own DC-DC converter, the LM2596S-5 can be used.

But it is an extremely bad idea to do so because both the component specifications and the board layout are critical. It simply is not worth the trouble given the price of ready-made modules.

Ok thanks, for the above.

Does that also go for the LM7805 voltage regulator which I already have . I know someone mentioned the heat from it, but it does have its' own heatsink attached.

If still a bad idea, I'll not bother then with a 7805, and buy one of those buck converters instead.

Thanks

Hi,
An LM7805 will be fine, a DC-DC converter is just more efficient.
Try what you have at hand, don't forget to add the bypass capacitors to the LM7805 that are recommended in the datasheet.

Tom... :slight_smile:

avalon66:
Does that also go for the LM7805 voltage regulator which I already have .

We don't know what total current is needed by your unnamed Arduino, breadboard and 3 x 5V boards. If it's low enough then a 7805 (with a few capacitors) will be o.k.

Steve

slipstick:
We don't know what total current is needed by your unnamed Arduino, breadboard and 3 x 5V boards. If it's low enough then a 7805 (with a few capacitors) will be o.k.

Steve

True, but part of the actual project is on a pcb board, buttons, resistors and connectors ,then there is a RTC DS1307 and a DHT22 on the breadboard, with a MAX7219 Vcc and GND wires connected to the power rails of the breadboard.

The arduino is a genuine Uno.

Hope that helps.
Thanks

Hi,

Can you please post a copy of your circuit, in CAD or a picture of a hand drawn circuit in jpg, png?

Thanks… Tom… :slight_smile:

The 7805 is not the pariah that some are making out. True, for digital projects it is less efficient than a buck converter but it is still a good regulator. Without any heatsinking, it will deliver up to a couple of hundred milliAmps. With a small heatsink, much more and up to an Amp with decent heatsinking. It is also fairly bombproof, fit the .33 on the input with .1uF on the output and just use it. It will just fold back if you try to abuse it current wise.

I hope this is ok, attached jpg

MAX7219 Dot Matrix 4-in-1 8x32 dot matrix common cathode.jpg

MAX7219 Dot Matrix 4-in-1 8x32 dot matrix common cathode.jpg

Better to have the buttons going from the pin to ground and pull-up resistors (if you need them as against using pinMode of INPUT_PULLUP) to 5 V.

Ok, I’m beat!

I tried a 7805 on the breadboard, then connected the input wires of the 9v power supply to the output and GND of the 7805. I have a wire from the board to the 5v pin on the arduino. Then I plugged in the 9v power supply and checked the voltage on the power rails of the breadboard and it’s just 5v.

The arduino does not power up, and hear you say not surpringly.

How should I connect the arduino either with the 7805 or a buck converter. I know I’ve missed something???

Thanks