Jencen_Dragoo
Posts: 5
Joined: Sat Nov 03, 2012 12:42 pm

onboard 5V regulator

Thu Nov 08, 2012 6:43 pm

Right. Another question ^_~

I've been poking at the schematics and it appears there's space for a 5V regulator circuit on the lower right of the board.

In the Schematics PDF there is the CCT diagram for this with a big note under it "Not used. Do not connect"

As far as I can see it doesn't connect to anything other than J8 beneath J7 for the 3V3 selector*.
Is this really the case?

As I'd find it VERY useful to have a good strong 5V source on the board to power arduino shields and servos and the like.
I know 5V is available from the Pi via J24 but that's limited by the Pi's internal fuse and all the current the Pi itself draws.

*Also noticed in the schematics that the 3V3 header isn't so much a power switch. but a selector between the regulated 3V3 and the Pi supplied 3V3 - Just for information if people can find this useful ^_^

Attached the reg schematics
3V3and5Vreg.png
3V3and5Vreg.png (62.51 KiB) Viewed 1822 times

User avatar
Gert van Loo
Posts: 2482
Joined: Tue Aug 02, 2011 7:27 am
Contact: Website

Re: onboard 5V regulator

Thu Nov 08, 2012 7:31 pm

I tried it out an found you can't use the regulator to power the board and the PI.
Not because the circuit is faulty but because it got waaaay to hot.
I even tried a big heatsink and still I would burn my fingers running from a 7.5V supply.
The regulator is still there in case you want to use it for supplying some other circuit. It is also standalone and not tied to 5V
so it can be used to make other voltage e.g. 12V (Just DON't place a jumper to the 5V of the raspberry-pi)
Finally: that circuit is NOT fused with all the risks that come with it.

Jencen_Dragoo
Posts: 5
Joined: Sat Nov 03, 2012 12:42 pm

Re: onboard 5V regulator

Thu Nov 08, 2012 8:30 pm

Gert van Loo wrote:I tried it out an found you can't use the regulator to power the board and the PI.
Not because the circuit is faulty but because it got waaaay to hot.
I even tried a big heatsink and still I would burn my fingers running from a 7.5V supply.
The regulator is still there in case you want to use it for supplying some other circuit. It is also standalone and not tied to 5V
so it can be used to make other voltage e.g. 12V (Just DON't place a jumper to the 5V of the raspberry-pi)
Finally: that circuit is NOT fused with all the risks that come with it.

Yeah am not looking to power the board and the Pi. Just any other little sensors and such that may be needed.

So i /can/ populate the empty area with a voltage reg of my choosing and not affect anything else on the gertboard? Just use it as a convenient other voltage source? (don't want to blow up my precious board now they are apparently in short supply.)
If so awesome ^_^ may even tinker with an adjustable one.

Been very happy with my board so far. It's got just the right amount of parts in one place to get me into electronics again ^__^ fantastic job.

User avatar
Gert van Loo
Posts: 2482
Joined: Tue Aug 02, 2011 7:27 am
Contact: Website

Re: onboard 5V regulator

Thu Nov 08, 2012 8:50 pm

So i /can/ populate the empty area with a voltage reg of my choosing and not affect anything else on the gertboard? Just use it as a convenient other voltage source?
YES! It is exactly the reason why I left all the traces and the schematic in place.
It is just a little beyond the targeted audience which is learning beginners to work with I/O.

Jencen_Dragoo
Posts: 5
Joined: Sat Nov 03, 2012 12:42 pm

Re: onboard 5V regulator

Thu Nov 08, 2012 8:56 pm

Gert van Loo wrote:
So i /can/ populate the empty area with a voltage reg of my choosing and not affect anything else on the gertboard? Just use it as a convenient other voltage source?
YES! It is exactly the reason why I left all the traces and the schematic in place.
It is just a little beyond the targeted audience which is learning beginners to work with I/O.

Awesome! ^_^

Many thanks for your replies

JohnCrow
Posts: 25
Joined: Fri May 25, 2012 5:28 pm
Location: Lincolnshire

Re: onboard 5V regulator

Thu Nov 08, 2012 9:38 pm

Hi Gert
Do you have a part no.(Farnell ?) for the coax power socket.
That way I can be sure to find one that I know will fit. All the other parts look to be fairly standard.

Thanks
1 in 10 people understand binary, the other one doesn't

Return to “HATs and other add-ons”