What happens if not enough mA?

[Guest marr]

What happens if my powersupply doesn't give enough mA?

I have a 9VDC/500mA and I'm starting to wonder if that's enough to run everything on the SEQ, with the two backlit 40x2 LCD etc... Should I start off with the pot for the LCD lighting all the way off and work up from there or what?

Am I running a risk of irritating (permanently) the PIC or LCD controllers or anything like that?

[Guest marr]

What happens if my powersupply doesn't give enough mA?

I have a 9VDC/500mA and I'm starting to wonder if that's enough to run everything on the SEQ, with the two backlit 40x2 LCD etc... Should I start off with the pot for the LCD lighting all the way off and work up from there or what?

Am I running a risk of irritating (permanently) the PIC or LCD controllers or anything like that?

[Guest kostix]

I would start from 1A and on

the powerfullier ur supply is, the better

the equipment wont take more than it needs,  so whats better than giving it virtually "limitless" supply and let it take how much it wants :)

[Guest kostix]

I would start from 1A and on

the powerfullier ur supply is, the better

the equipment wont take more than it needs,  so whats better than giving it virtually "limitless" supply and let it take how much it wants :)

[moebius]

Hi,

I think that doc would be better to answer this, but anyway:

If your regulator can't supply enough power to the circuit, it overheats - and thermal protection kicks in, it starts to limit current, by droping output voltage. (remember your U/R=I)

This probably leads to strange behaviour, random resets ect.

If your transformer is underrated, then everything might seem like normal, as regulator can suck enough power out of it anyway, BUT transformer heats up, let's say more than in normal use.. (Or it might even have a fuse that blows.. but usually no thermal protection.)

This shortens expected "life" of the transformer and in extreme cases can lead to fire hazard..

Bye, Moebius  

[moebius]

Hi,

I think that doc would be better to answer this, but anyway:

If your regulator can't supply enough power to the circuit, it overheats - and thermal protection kicks in, it starts to limit current, by droping output voltage. (remember your U/R=I)

This probably leads to strange behaviour, random resets ect.

If your transformer is underrated, then everything might seem like normal, as regulator can suck enough power out of it anyway, BUT transformer heats up, let's say more than in normal use.. (Or it might even have a fuse that blows.. but usually no thermal protection.)

This shortens expected "life" of the transformer and in extreme cases can lead to fire hazard..

Bye, Moebius  

[pay_c]

Counting the Seq:

2x LCD backlight appr. at 200 mA = 400 mA

The whole schematic (including core, DIN´s, DOUT´s): about 50 mA - 100 mA

LEDs: from 0 up to more than 300 mA (!!)

So with the Seq you´re some good kinda over the 500 mA.

Greetz.

[pay_c]

Counting the Seq:

2x LCD backlight appr. at 200 mA = 400 mA

The whole schematic (including core, DIN´s, DOUT´s): about 50 mA - 100 mA

LEDs: from 0 up to more than 300 mA (!!)

So with the Seq you´re some good kinda over the 500 mA.

Greetz.

[doc]

Start with 1A min.

500mA doesn't make sense in your case !

greets

Doc

[doc]

Start with 1A min.

500mA doesn't make sense in your case !

greets

Doc

[Guest marr]

Thanks all for confirming my suspicions.. I suppose now I might need to look into getting a bigger heatsink for the 7805.

[Guest marr]

Thanks all for confirming my suspicions.. I suppose now I might need to look into getting a bigger heatsink for the 7805.