Monthly Archives: January 2012

Mosquito attractants for an effective trap

Clearly various species of female mosquitoes and myself seem to have a slight communication issue. Having been forced into this rather parasitic polygamous relationship my patience has, after over two decades of torture, finally run out. Furthermore considering that various mosquitoes act as vectors for diseases such as yellow fewer and malaria I do not wish to push my luck any further during my future trips into the rainforests of this world. Hoping to build an effective, affordable and portable trap it is as a first step necessary to understand what exactly mosquitoes are attracted to.

Female Anopheles albimanus mosquito

Female Anopheles albimanus mosquito while she is feeding on a human host, thereby, becoming engorged with blood. (Source: Center for Disease Control and Prevention, ID 7861)

“Using their highly sensitive olfactory organs, these mosquitoes can select more attractive persons over less attractive ones by identifying chemicals present in breath, sweat and other skin emanations originating from the persons. Though not adequately understood, these evolutionary host preferences may benefit the mosquitoes in a number of ways including the identification of hosts with more nutritive blood, or those who are less defensive against mosquito bites.” (Okumu et al. 2010) In the following paragraphs various possible attractants will be investigated as a potential suitable lure for the trap.

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Logitech C910 and C920 IR (Infrared) conversion for nightvision

This is a tutorial on how to convert your Logitech C910 or C920 webcam into an HD nightvision camera by removing the Hot Mirror Filter. For the C920 please read the comments. Once you have completed the conversion, your camera will be very sensitive to infrared light. However, it should be noted that one of the main reasons for the IR filter’s existence is to get a sharper image. The quality of the image is thus affected and furthermore your webcam image will have a very strong red tint. (Of course if you would use a lightsource without infrared, such as an LCD, that would not be the case.) Furthermore, in my case the autofocus does not seem to work very well after the conversion. The manual focus on the other hand works just fine, This is all I need for my purpose.

Please note that you are converting the camera at your own risk.

Below you find an image taken with my converted C910. The picture was taken through a 850nm IR filter. The LED’s are 950nm. Looking through the filter the room appears absolutely pitch black to the naked eye.

Photo of two 950nm IR LED's taken through an 850nm IR Filter with the converted Logitech C910.

Photo of two 950nm IR LED

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Ultrasonic Dimmer (without humming or buzzing noise)

Arduino based Ultrasonic Dimmer

I have been working on this project for a while and whilst it is still under development here’s a short guide after several requests to do so. The dimmer uses an interrupt driven XL-Maxsonar EZ1 ultrasound range finder to measure the distance between the sensor and your hand. By moving your hand up and down over the sensor you can increase or decrease the amount of light emitted by the connected halogen lamp.

In this post I will explain how one can make the basic dimmer based on a simplified circuit. This dimmer later evolved to include an LCD, SHT15 temperature and humidity sensor, DS1307 realtime clock and a mosfet driver to drive the mosfet above 30Khz so the unpleasant dimmer humming noise would disappear. I will talk more about this later.

First things first, here’s a movie of the latest version of the dimmer in action, it includes an LCD, a temperature and humidity sensor, a realtime clock and an alarm function that simulates a sunrise:

YouTube Preview Image

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