future power suply unit question!

[t.man]

any one to help with a power suply circuit for a microcontroller project. i.e the power suply unit i'll be using for my final implementation.

presently i'm testing my circuits with 12VDC plug-pack suplying 78L05.

 

[Hero999]

We don't know your requirements so it's impossible for us to help.

 

[Edmond]

Hi!

I’m not familiar with your project, but I think that the 78L05 will be too poor. If you are using 12V source, 7V will drop on the regulator. Imagine, when your board is drawing 100mA, the regulator’s power dissipation is 0,7W. It will become too hot very quickly. I suggest you to use 7805 with heat sink package and screw the regulator on the cooper surface of the PWB. Important, the heat sink is connected to the GND pin. The best way to use a low-drop regulator (like LM2931A-5) and a lower voltage source (7-8V).

 

[Torben]

Hi!

I’m not familiar with your project, but I think that the 78L05 will be too poor. If you are using 12V source, 7V will drop on the regulator. Imagine, when your board is drawing 100mA, the regulator’s power dissipation is 0,7W. It will become too hot very quickly. I suggest you to use 7805 with heat shrink package and screw the regulator on the cooper surface of the PWB. Important, the heat shrink is connected to the GND pin. The best way to use a low-drop regulator (like LM2931A-5) and a lower voltage source (7-8V).

Hi Edmond,

I agree overall with your assessment, I just wanted to clarify something quickly: I think you meant "heat sink" instead of "heat shrink".

I'm only mentioning it because if the OP took that literally and put heat shrink tubing over the regulator he might wonder why it burned up even faster.


Regards,

Torben

 

[t.man]

We don't know your requirements so it's impossible for us to help.

it entails micro with ADC readings and calculations, USART and outputs for LCD display and LEDS and if necessary an alarm!

 

[ericgibbs]

it entails micro with ADC readings and calculations, USART and outputs for LCD display and LEDS and if necessary an alarm!

hi,
Whats wrong with your present setup.? 12Vdc adaptor driving a 7805 reg.

It will be sufficient for all the functions you have listed.

 

[t.man]

hi,
Whats wrong with your present setup.? 12Vdc adaptor driving a 7805 reg.

It will be sufficient for all the functions you have listed.

actually i'm an amateur when it comes to electronics!...i thought an adaptor as only for circuits on my table now(on the breadboard)! and i thought of something else when it comes to PCB and real implementations...i posted this thread to dig some relevant info.

thus anything useful i'll appreciate it!

kinds regards!

 

[ericgibbs]

actually i'm an amateur when it comes to electronics!...i thought an adaptor as only for circuits on my table now(on the breadboard)! and i thought of something else when it comes to PCB and real implementations...i posted this thread to dig some relevant info.

thus anything useful i'll appreciate it!

kinds regards!

hi,
For most applications a power adaptor plug say 12V thru 24V 'regulated' about 500/1000mA is OK.
Its difficult to beat the shop bought unit on price, if you take into consideration the cost of all the parts and time
to make your own..
If you want to build one as a learning project thats a good idea also.

 

[Edmond]

I agree overall with your assessment, I just wanted to clarify something quickly: I think you meant "heat sink" instead of "heat shrink".
Torben

Yes, sorry. I corrected it.
THX

 

[ikalogic]

I'm only mentioning it because if the OP took that literally and put heat shrink tubing over the regulator he might wonder why it burned up even faster.


Regards,

Torben

Now that's a really funny scenario! lol

 

[arrie]

Now that's a really funny scenario! lol

Yes, now you can see that to condomize is not always the best solution.

 

[ikalogic]

Yes, now you can see that to condomize is not always the best solution.

what do you mean by "condomize " .. is it like "encapsulate" ?

If it's funny, can you explain?

 

[arrie]

Mmmmmm

The chip is in a condom, get it.

 

[ericgibbs]

Mmmmmm

The chip is in a condom, get it.

A picture is worth a thousand words..... we are waiting 'aarie'.....

I use a plate with a fork when eating chips, I suppose you are talking about french fries.

 

[ikalogic]

lol... that's what i got at the beginning, but it took me some time to imagine the picture..

 

[arrie]

Torben was pointing out an interesting misprint, the heat shrink in place of the heat sink for the regulator.
Now picture heat shrink over the regulator, shrunken down everything.
It would probably look like as if the reg, that's what I meant with chip, is wearing a little condom.
I just wanted to say it in a really funny way.

Eric if you want, I can probably still get a couple of pictures together, but I think I killed the joke already.

 

[ikalogic]

It was the expression "condomize" that was too sophisticated for me...

 

[arrie]

It's probably a south african term.
Condomize: to use the related and obvious protection (a condom) in cases where........

sorry cannot go on with definition, it will break too many rules here

 

[t.man]

hey, guys!

what have u agreed is the best solution to the thread?

 

[Torben]

hey, guys!

what have u agreed is the best solution to the thread?

Welcome back! Sorry, we kind of went off on a tangent there. Eric answered your question in the second post.

Do you have specific questions about the setup?


Torben

[P.S. On these forums it's considered good form to take the time to spell the whole word "you". ]