New Jarduino build gets started

[Goatman]

Originally Posted by daplatapus

Ok, so maybe I did something wrong... maybe.

I took this step down transformer and took out the 2 stock resistors. I put a jumper where one resistor was and installed a variable resistor where the other was. Plugged it in and POP!!!! blue smoke, HOLY CRAP!! Fire! lol, extremely exciting.

What did I do wrong???






I tested the variable resistor and the centre leg is the wiper and the other 2 legs are either side of the resistor. I used the back leg so the further out the adjustment screw was the lower the voltage, turn it clockwise and the voltage increased. the unused leg is the one you see sticking out of the variable resistor.

Should have used the newer smoke free ones...duh

[ScubaSteve]

Where did the smoke come from Dom?

[ScubaSteve]

BTW, I still have all the parts for a LM2575-ADJ adjustable stepdown converter if you want them.

[daplatapus]

Originally Posted by ScubaSteve

Where did the smoke come from Dom?

It came out of the top of the 1000uF high temp capacitor. The brown one on the left, you can kind of see where it blew the 3 embossed triangles open at the top.
I did find some of the LM2576HV Chris was talking about on ebay for fairly cheap. But I kinda wanted to get what I have working, since, well you know, I have them

[Chatouille]

Well... actually one less now

The LM2576HV i have works well, stays cool, and is able to step down from 48VDC. Most of the other dc/dc converters are limited to ~36v, but the biggest selling point is that they come pre-assembled.

Here's that schematic for the fan.

[daplatapus]

Hmmm, pic is too small to make out. I tried saving it and zooming in but it went all blurry... unless that's the aftermath of the exploding transformer

[Chatouille]

lol.... sounds like Bill Clinton. Tranformer smoked, but I didn't inhale. Why is everything so blurry?

[daplatapus]

Nope, didn't inhale. No really...

Well I had a few minutes tonight so I finished soldering up one proto board and hooked up one of my waterproof temp sensors. After figuring out the address of it, modifying and re-laoding the sketch, all works well

[daplatapus]

Originally Posted by Goatman

Should have used the newer smoke free ones...duh

Ahhhh, but I hear it takes quite the expertise to get these ones to release this particular smoke, lol.

[KrazyKuch]

Originally Posted by Goatman

Should have used the newer smoke free ones...duh

I didnt see if anyone told what you did wrong here and I know your past that but for future reference for anybody else it looks like those 2 original resistors were in parallel and by putting in a jumper you basically jumpered out your variable resistor....ie you removed the resistance from the circuit, hence the smoke!!!