The new lab, again and a fish light controller

Nothing special in todays update but I figured I’d post a few things for the fun of it. First off I guess is my lab. I’ve been using it for a month or so. A little small, but at least it’s not at work.

New lab as of April 2011

Nothing to write home about I guess, but I feel comfortable here! Anyways, my little project for the day is the fish light. My bulb burnt out in my fish tank and since it was a high UV one I’ve decide to make an LED version. Since I have an array of LED’s I decided to go with some Whit, UV and a few red ones for good measure (I don’t like blue LEDs).



And here’s the breadboard, messy!


the LED driver on the breadboard

The LED’s are driven on 4 channels with PWM output on separate channels. The idea for me is to provide an on-timer for the cycles through the day and to provide a source of UV light for the plants. The diodes are driven by 4 TIP117’s so that each channel (White, UV, Red) can be controlled individually based on whatever profile I want.

Unfortunately I’ve discovered that the number of LED’s that I used is insufficient for use in the tank, not enough light. So I’ve ordered over 500 white LED’s and 150 UV led’s and 100 Red LED’s. I won’t use them all but it’s always good to have LED’s. One issue may be driving all of these LED’s. I have a maximum output of 1A on each of the PNP TIP117’s so an output of about 14W is all I can produce. Hopefully that’ll be enough!

Again LED Array

Again, the LED Array

Anyways, here’s hopin’!

Personal Projects

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Little LCD tester

Well, after some playing around and getting my electronics feet back, I’ve finally rediscovered some passion. This little project is something I’ve wanted to do for quite some time. Basically it’s an HD44780 LCD tester. A very simple device but if you’re like me, when you receive an LCD in the mail, you want to be able to see the device in it’s glory.

The board inside the LCD tester

The board inside the LCD tester

I just made it with a PIC16F690 MCU and some random components. The output is of course the LCD but also two LEDs. The unit has provisions for the backlight though it’s just straight 5v out, you have to worry about resistances when you hook it up.

The button on the back of the unit basically prints extra 20 character long strings so you can see how the memory is addressed and see how things scroll over in printing.

Anyways, here are pics:

Finished unit from the back

Finished unit from the back. 5v barrel connector and a toggle switch for power

The unit from the front

The unit from the front. just the LEDs and the pinouts. Also note the knob on the top for the pot. that's for adjusting contrast.

The text out

The text out. this one on a 2004 lcd

Well, there we go. This will be a handy little device for testing whether any of them are any good.


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Coolant mixture sensor (psuedo-refractometer)

A bit ago I got the idea of trying to determine the mixture of coolant vs. water by detecting both light occlusion of the mixture and the wavelengths blocked / passed. This initial device is just a rough prototype that will assist me in determining a course of action in regards to overall design.
The idea behind the device is to have the sensor fitted on to any pipe attached to the machine where coolant goes through and give a live measurement of coolant mix and alert the operator if the mix gets too high or low. Also I’d like it to detect tramp oils that have been beaten in to the coolant.

Coolant meter board

The board itself is pretty simple, just a PIC16f690 hooked up to an rs232 driver and using three analog channels. I may in the future build a more sophisticated ADC board, but for now, this will do. The mcu is linked to the two rail to rail opamps, 7014D’s to be exact. they were needed to condition the signal from the LEDs.

Coolant meter test receptacle

The sensor area is basically a cup with a white LED as a light source for the sensor LEDs. The three LEDs are IR, Orange-red, and Green. The LED’s respond to wavelengths more energetic than the ones they emit, therefore, the selections I made. I did try a blue LED but the response wasn’t good at all. Hopefully it will provide useful data, hopefully.

Coolant meter terminal output

In order to make data easier to collect, I put rs232 communications on it. I can store and track data this way. Above is some of the terminal output. Notice that I’m taking 10000 samples… this has the effect of increasing, to a very limited degree, the resolution of the device. It is however fraught with error thus far…
Anyways, any data collected and the design of this is extremely preliminary. I’m not even sure it’s a valid or useful idea yet.
As an extra bonus, or punishment, here’s a video I made for this device.


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