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361  Using Arduino / Project Guidance / Re: PCB Layout review on: July 10, 2012, 07:49:28 pm
Very nice, love seeing the finished project
362  Using Arduino / Project Guidance / Building a power supply for a Nano on: July 10, 2012, 07:31:34 pm
Hi all. I need a way to power a Nano from 240v in a tight space.

I have hooked up a isolation transformer http://uk.rs-online.com/web/p/products/732-0531/ (6v @ full load) and a bridge rectifier http://uk.rs-online.com/web/p/products/629-5169/ (1v drop).

measuring off load after the rectifier I get almost exactly 7v DC - connected to Vin on the nano I get about 6.5v however the Nano won't start up, and moments after the power LED comes on, the TX & RX LED's also light up, and the pin 13 LED comes on dimly.

I'm not sure whats going on here - when I try with a bench PSU the Nano boots and stays on down to 5ishV? With my PSU and the Nano in the weird state it pulls about 12mA, but with the bench PSU the Nano draws about 25mA?
363  General Category / General Discussion / Re: Anyone used suntekstore.co.uk? on: July 09, 2012, 06:40:33 pm
Oh I see that makes sense, thanks for the heads up Mike. It's kind of hard to know what the limit would be I guess, under £5 be OK?
364  General Category / General Discussion / Re: Anyone used suntekstore.co.uk? on: July 09, 2012, 11:16:43 am
Ah right thanks. I guess it should be OK because I think I the UK you don't pay import tax on goods under £10-15, just a shame shipping takes forever!
365  General Category / General Discussion / Re: Anyone used suntekstore.co.uk? on: July 09, 2012, 07:04:53 am
Thats what I thought, it looks a bit suspect. Just gone as far as the cart though and doesn't say anything apart from free postage?
366  General Category / General Discussion / Anyone used suntekstore.co.uk? on: July 08, 2012, 08:37:06 pm
Just found this site, some very good prices on electronic bits indeed and states free shipping - but I have never heard of it before?

http://www.suntekstore.co.uk/category-101-b0-diy_parts_tools.html
367  Using Arduino / General Electronics / Re: Using a PCB transformer on: July 05, 2012, 11:40:25 am
Thanks again all.

@CrossRoads - I could probably get similar but that would not fit in a socket flush mount back box, although I could mount it remotely but that would mean more cables running to the device because I still need to run mains to my project (its a thermostat). Thanks for the idea though its one I haven't yet considered.

@SirNickity - Thanks that's some really useful info there. I think I might pick up a 6v transformer and test it out using only the nano regulator before I finalise a PCB. Also good point about the fuses!

368  Using Arduino / General Electronics / Re: Using a PCB transformer on: July 04, 2012, 06:53:47 pm
I do think its good we rely on fuses so much, just a pity so many people don't think about the value they stick in the plugs!

Back to my project, I have just thought... why don't I use a 6v transformer http://uk.farnell.com/myrra/44085/transformer-1-5va-6v/dp/1689047

same footprint, almost same current output and surely will leave less work to do for the Nano's regulator?
369  Using Arduino / General Electronics / Re: Using a PCB transformer on: July 04, 2012, 09:01:38 am
That's true, the supply will be fused at the plug anyway.

So is the general consensus to use a primary regulator before power gets fed into the Nano then?
370  Using Arduino / General Electronics / Re: Using a PCB transformer on: July 03, 2012, 06:41:10 pm
@ SirNickity - thanks for the input, I will be fusing the input to the transformer also - I guess ohms lay would apply to select a sensible value? It will draw max 200mA, but I have calculated that my circuit won't draw more than 100mA. How would I calculate the input current @240v?

@ jackrae - thanks for the advice. Surely a primary regulator would be subjected to the same stress as the Nano regulator, or are you suggesting to use a larger one to dissipate heat easier than the nano? Would I be better off using a single 5v regulator and to power the entire circuit and the nano?

@ CrossRoads - thanks, if I add a regulator should I just follow the recommended capacitor values from the relevant datasheet?

Size is a real issue as I'm mounting the project in a standard wall socket double back box, but I can hopefully squeeze a couple of extra bits in there smiley





371  Using Arduino / General Electronics / Re: Using a PCB transformer on: July 03, 2012, 01:16:13 pm
Sorry guys I should have said where the power will be going - it will be running a Nano only and the on-board regulator will do the rest of the work (LCD screen and couple of LED's).

Will I need anything other than a rectifier for that purpose or can the Nano V-reg  deal with the rest of the task?

Thanks
372  Using Arduino / General Electronics / Using a PCB transformer on: July 03, 2012, 12:42:25 pm
Hi all. I plan to use a PCB transformer in my next project (240v to 9v). I'm wondering if any additional components will be required - I know I will need a bridge rectifier to convert the AC output and I'm also putting a fuse on the o/p, but is there anything else I should add, such as capacitors?

This is the transformer I plan to use http://uk.farnell.com/myrra/44122/transformer-2va-9v/dp/1689054?Ntt=1689054
373  Community / Exhibition / Gallery / Re: Arduino Paper Television on: June 25, 2012, 08:20:19 am
very cool! any photos of the inside?
374  Using Arduino / Programming Questions / Re: Time lapse controller, swapping delays for timed functions on: June 13, 2012, 07:59:06 pm
Sorry I had the focusDelay to short to notice the while loop passing. It's working now and doing what I wanted, probably the entirely wrong way to do things but I'll continue to work on it!

Now it prints a countdown until the loop passes to the LCD which is what I was hoping to achieve

Code:
//Trigger focus
      unsigned long timer1 = millis();
      lcd.clear();
      digitalWrite(focusPin, HIGH);
     
      int countdown = 0;

      while (millis() - timer1 < focusDelay)
      {
        //hold focus button down and do nothing else for x seconds
        lcd.setCursor(0,1);
        lcd.print("test");
       
        countdown = focusDelay - (millis() - timer1);
        lcd.setCursor(1,0);
        lcd.print(countdown / 1000);
        lcd.print("s        ");
375  Using Arduino / Programming Questions / Re: Time lapse controller, swapping delays for timed functions on: June 13, 2012, 05:40:23 pm
cant get it to work smiley-sad It seems to enter the while loop, but does not execute its contents, and also does not exit the loop at all

what am I doing wrong here guys?

Code:
//Trigger focus
      unsigned long timer1 = millis();
      lcd.clear();
      digitalWrite(focusPin, HIGH);

      while (millis() - timer1 < focusDelay)
      {
        //hold focus button down and stay in this loop until focusDelay has been reached
        lcd.setCursor(0,1);
        lcd.print("test");
      }
      lcd.clear();
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