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Arduino Temperature Display

August 18th, 2008
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This was more of a proof of concept, a “I can do it” sort of project. I had purchased the LM35 so long ago with plans to use it with a PicMicro.

I had purchased a couple of the Freeduino SB boards from Solarbotics, and found that I liked the quick/rapid prototyping it offers. Its my first experience with the Arduinos, and apart from limited availability of the microcontroller, and an incorrect capacitor on the power supply, I’ve been pleasantly surprised.

I actually desoldered the capacitor out of the circuit to regain full voltage control of the board, and for future ones I’ll also have to desolder the vreg, since I prefer to use a switchmode and I’ll bypass some of the board control with my switch to save battery power.

LM35 is hooked up into Analog 0, and the reference is set to internal, which switches the 5V reference to 1.1V. Measured with my DMM, it was closer to 1.043 and that is so close to the magic 1.024 number that the raw value is closer to the true reading from the LM35.

The LCD is the SLCD162 MeLabs LCD Display, which I also picked up from Solarbotics.

The LM35 is taped to an old northbridge heatsink, which provides a closer “In Air” reading.

I’ll be tearing apart this circuit to use the microcontroller in another project, but at least it will have some memory resting here on the site.

Sketch

LED Tester

August 17th, 2008
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While I was working for a manufacturing company, we would occasionaly go through our scrap parts from the machines, and at times would find hundreds of LEDs. They could be saved and used on the next run, but we had two issues:

1. What color was the LED?

2. Polarity on the surface mounts?

This tester was made to make my personal life easier. Output is limited and pulsed at a 50% duty rate. Power is delivered to a set of multimeter leads that were lying around the shop. A PIC12F675 was programmed for the 50% duty.

There are two modes in the tester, with a bicolor LED to indicate which mode is active. The pic reads the switch position and is configured to reset on change. Green indicates red lead = positve and black lead = negative. Red indicates not polarity sensitive. In this mode, the pic swaps the positive and negative continuously so that the LED will illuminate regardless of polarity. This let me sort through the hundreds of LEDs quickly, placing each color in its own container, and then determining polarity later, during the production runs.

Overall, a very simple design. The PIC12F675 is socketed to allow program updates. (Never needed any) The battery here is the same one I built it with, which is now over 6 years ago. Although I don’t comb through hundreds of surface mount LEDs, the tester is still handy. The pushbutton switch is wired directly to the 7805 vreg, and I didn’t require any bulky capacitors in the circuit, since we’re dealing with pure DC.

Most of the parts were scavenged from scrap units we had at the time. The container is an old toothpick canister. Hot glue and tie-wraps were my best friends on this build. The blue wire we had at the shop for repairing damaged PCBs.

Site gets new life

August 9th, 2008
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Well posting has been slow lately, which if anyone is left reading these, isn’t a surprise.

I have been playing with some electronics lately and wanted to start keeping track of some of them and thought why not use this space, since its paid for.

So there’s a couple of new categories that will be appearing, Electronics and Robotics. I apologize in advance to anyone who doesn’t care for either. I’ll still post some nice pictures of our flowers and other nice nature stuff too.

It is a good decision for me, however, and a bit inspired by this guy:

http://www.danielandrade.net/2008/07/05/temperature-sensor-arduino/

I liked the idea of sharing with people and even getting feedback, and so It is done! 🙂

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