We’ll learn the design of resistors on base of MLT type resistors, which are widely spread in radio electronics. Fixed, non wire-wound resistor MLT (Metal film, Lacquer, Heat-resistant) has the axial ceramic base in the form of a tube or a rod covered with a thin metalized layer of film made of special resistance material. The film thickness is less than micrometer for all values. The difference between the values of resistance is set by changing the composition of resistive layer and the number of spiral turns cut on the axial surface of ceramic base. Figure 7 shows the details of resistor design.
1 – Outer moisture-resistant enamel coating;
2 – Resistive film, conductive layer;
3 – Ceramic base of resistor;
4 – Metal guard;
5 – Axial metal leads.
There are metal guards with axial wire leads on both ends of ceramic base. With the help of these leads resistor can be soldered to electrical circuit. The outside of resistor and conducting resistive layer are covered with the layer of waterproof organic enamel to protect them from the impact of moisture and mechanical damages. The enamel coating of red colour is usually used for resistor of MLT type, on the surface of which the resistor marking is put.