AVR-Chat

> -----Original Message-----
> From: Adam Read [mailto:asread@bigpond.com] 
> Sent: Friday, 19 March 2004 8:28 PM
> To: AVR-Chat@yahoogroups.com
> Subject: [AVR-Chat] Re: back-up power supply circuit
> 
> 
> Kat: Thanks for spotting my stuff-up.  It only really clicked when I 
> read your post and I thought "well now, I'm an idiot" (although, 
> realistically, I used much worse language!).  I do tend to forget 
> things that are that obvious, guess I was in a hurry to help/'show 
> off'/any excuse I can think of later.... at any rate I'll just go 
> kick myself now (ow!).  

No worries mate, we all make mistakes, I have made some major ones (like
sending a PCB to be fabbed upside down, so all the IC's had to be
mounted on the under side (these were the good ol days of tape and film
lol)


 
> Jay: No, you won't need another supply for this circuit.  What I was 
> attempting to describe (and I very rarely explain things properly 
> the first time, so please bear with me) was thusly:
> 
> When the primary power is on, the relay is energised, and power 
> passes through the primary pin to the switched pin which then feeds 
> the on-board regulator, which feeds onwards to the circuit.  Of 
> course, as Kat pointed out, you will need a diode to prevent my 
> lovely caps from keeping the coil energised for a period.  The 
> primary supply comes in along a track to your switching circuit.  At 
> some point the track will split, as shown: (again, please excuse my 
> crap ASCII art)
> 
>          _______  Relay coil
>         /
> -------<
>         \----|>--- Pin supplying primary power to switched pin.
> 
> Please note Kat's diode, shown correctly on the 'supply pin'.  As 
> Kat described, it will prevent the caps further down the lin (after 
> the switched pin) from keeping the relay energised and not allowing 
> the switching to occur until the caps are drained, and the micro has 
> lost most of its power and likely reset.
> 
> Hopefully this will help you with your project, and I hope you 
> understand what I'm trying to get at here.  If not, feel free to let 
> me know.  We are all here to help each other, after all.
> 
> Cheers,
> Adam.

I have uploaded a gif to the files section showing how it is done.

Regards,

Kat.



---
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.618 / Virus Database: 397 - Release Date: 9/03/2004