Posted by Todd Somers [108.162.236.193] on Friday, March 25, 2016 at 16:16:37 :
In Reply to: Re: 6 volt heater on 12 volt truck posted by Jerry in Idaho [108.162.221.41] on Friday, March 25, 2016 at 01:29:37 :
The Runtz voltage "reducer" shown in the picture is actually a resistor that was made with an anodized metal heat sink incorporated with the resistor inside when the resistor was made. Look at the Runtz resistor and there should be a value in ohms and a wattage rating printed on it unless the resistor was "custom" made for Runtz. Resistors were once commonly used to drop voltage down based on ohms law calculations. For dropping half of 12 volts to a motor, they generate a great deal of heat consuming the same amount as the load, thus doubling the current. When the resistor gets hot the resistance will change, thereby changing the voltage to the circuit load. Large wattage resistors are no longer used in modern electrical and electronic power supplies any more due to the waste of electric current and unwanted heat that is produced. High wattage resistors have been replaced by solid state devices and circuitry that can perform precise voltage regulation and generate a minimum of heat in the process.
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