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1  Using Arduino / General Electronics / Re: Resistor identification on: April 11, 2013, 12:00:19 pm
@ CrossRoads - nice find, that looks like the one. Thanks

@ dannable - No, I don't know why it burnt out, but I do know that a new board is £480 + vat, so I'll try replacing the resistor, first.
2  Using Arduino / General Electronics / Resistor identification on: April 11, 2013, 09:44:16 am
I am trying to identify and replace a burnt out resistor:

I think it's the same as its neighbour to the right, a brown black brown gold. The burning makes the rings hard to see. They both give 100 Ohms in situ. The thing is, it's huge - 15.3mm long and 4.3mm in diameter.

Does that make it a 100 Ohm, 5%, 2 Watt? Where is the best place to get such a thing in the UK?

3  Using Arduino / General Electronics / Identify temperature sensor? on: April 07, 2013, 05:51:50 pm
I have a temperature sensor on a board which measures room temperature. I am convinced that the sensor is faulty, so I need to identify it so that I can replace it.

The sensor has two pins and is square in profile, about 3mm x 3mm x 2mm, with no identification markings, although there are two white patches on the top, and a semi-circular marking on one face, but that may be just chance. There is some sort of white sleeve on the pins.

How am I to go about getting the correct replacement? I've got a very good multi-meter. Thanks.

4  General Category / General Discussion / Re: Transistor identification on: March 02, 2013, 06:45:43 am
That's actually a very helpful comment, Lefty. There is a fault on this board that is keeping the heat recovery unit in permanant defrost mode, even though I've got the board set up on the bench with all its "peripherals" working correctly.

All the components on the board look OK, which is why I came to the conclusion that a voltage spike must have damaged something, so I am trying to identify the components with a view to testing / replacing them one by one.

I came to this forum because I was going to build an Arduino based replacement for the board, but I think that is beyond my skill set for the time being, so I'm carrying on trying to troubleshoot the old board.
5  General Category / General Discussion / Re: Transistor identification on: March 01, 2013, 03:46:01 am
Thanks Lefty

These two components are next to each other, just after a bridge rectifier and capacitors, the regulator first and the transistor / voltage sensor second, on a board that I suspect has suffered a voltage spike. It's a 20 year old heat recovery unit.

There's plenty of youtube videos on how to test faulty transistors, but how do I test it if it's a faulty voltage sensor?
6  General Category / General Discussion / Transistor identification on: February 28, 2013, 05:45:19 pm
I think it's a transistor...

It's from a 20 year old board. Can a datasheet be found for it and / or what is the modern-day equivilant to replace it with?

Also this:

I assume it's a 5v regulator. Will any 7805 regulator do as a replacement?

7  General Category / General Discussion / Re: Circuit design software on: February 25, 2013, 08:12:00 pm
Thanks for the suggestions, I'm checking them out.

As a side issue, I have a very troublesome professionally made, 20 year old control board, which has caused me endless problems (the manufacturer can't offer support). Can I use any of these programs to create a schematic of the traces and components of this board, to try and work out how the board works. I have found that there are some ICs on the board that aren't in the library of these programs. How do I get around that? The part numbers are visible. Thanks.
8  General Category / General Discussion / Re: How to tell if my Ethernet Shield is counterfeit on: February 24, 2013, 06:36:32 pm
Is this set of 8 relays OK (as in not counterfit)?

It seems very cheap at £5.59

A Leonardo would need an additional 5v power supply to to run the 8 relays, right?
9  General Category / General Discussion / Circuit design software on: February 24, 2013, 06:29:03 pm
What circuit design software do you people recommend? Nothing too expensive, suitable for a novice. Thanks.
10  Using Arduino / Project Guidance / 1 year timer with Leonardo on: February 24, 2013, 03:25:39 pm
I am using a Leonardo to create a replacement control board for an air conditioner.

The Leonardo is taking information from sensors, and controlling a bank of 8 relays.

Part of the system requires an alarm (an LED) to remind the user to clean the air filters every, say, 1 year. What hardware do I need to add to the Leonardo to acheive this? Do I need a second Leonardo? It really ought to be able to remember where it has got to, and be able to carry on from there, if there's a power cut.

Thanks for any suggestions.
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