Thanks to internet and Yahoo! Groups I found another solution to protect the corrector plate against the dew, so I decided to stop using the dew shield. At that time the project was a little bit ambitious because it was based on electronic components. Therefore, I decided to build a dew heater. Technique is based on Ohm role. That means when current goes through a resistor, this resistor produces heating. This phenomena can be written with the following formula: P = UI. Where P is the power in watts, U is the voltage in volts and I is the current in ampere. The goal is to use several resistors at the same time, so as to produce enough heating on the corrector plate. So there is another factor to keep in mind. Indeed, in order to produce heating it is necessary to have a minimum of voltage.

For security reasons it will be safer to use low voltage up to 15 volt. For this job a computer power supply will be suitable. But this kind of product can support an amount of ampere which has to be linked to the resistance of the montage. To resolve this equation it is important to do some tests with a few numbers of resistors, a battery and then check your result to save time and components with an electronic software. To conduct my first test I used a 1Kw resistor and a 4.5V battery. When I connected the resistor to the battery, it immediately burnt!. After reading more on the subject, I understood why it burnt and designed several solutions to produce my first 34 watts prototype.