Resistors Fixed Composition
Revealed by: Callie
On: 04 Jul, 2017
Viewed:346 times - 21 hour, 13 minute, 22 second ago
Downloaded: 0 times -
Resistors Fixed Composition including:
- Color Code
Standard resistors are furnished in percent tole...
Resistors Fixed Composition including:
- Color Code
Standard resistors are furnished in percent tolerances, and in the preferred-value series of Table 2. “Even” values, such as 50 000 ohms, may be found in old equipment, but they are seldom used in new designs.
- Packaging Styles
In addition to the familiar axial-lead configuration, resistors are also available in SIP (single in-line package), DIP (dual in-line package), flat-pack, and leadless chip configurations.
The SIP and DIP types are designed for thru-hole or socket mounting on printed circuit boards. Flat-pack and chip configurations are surface mounted.
Flat-packs, SIPs, and DIPs contain multiple resistors, which may be internally connected to form networks or to have a common terminal pin. The chip configuration allows increased component density and is auto-insert able. Since there are no leads, basic circuit reliability and high-frequency performance are improved.
- Temperature and voltage Coefficients
Resistors are rated for maximum wattage at an ambient temperature of 70 above these temperatures up to maximum allowable hot-spot temperature of 130 or 150 , it is necessary to operate at reduced wattage ratings. Resistance values are a function of voltage as well as temperature; present specifications allow a maximum voltage coefficient of resistance as given in Table 9 and permit a resistance-temperature characteristic as in Table 10.
A 1000-hour rated-load life test should not cause a change in resistance greater than 12% for watt resistors and 10% for all other ratings. A severe cycling humidity test may cause resistance changes of 10% average and 15% maximum; 250 hours at 40 and 95% relative humidity may cause up to 10% change. Five temperature-change cycles, -55 to +85 , should not change the resistance value by more than 4 % from the 25 value. Soldering the resistor in place may cause a resistance change of 3 %. Always allow -inch minimum lead length; use heat dissipating clamps summary indicates that close tolerances cannot be maintained over a wide range of load and ambient conditions.
Composition resistors above 1 megohm have high Johnson noise levels, precluding their use in critical applications.
The end-to-end shunted capacitance effect may be noticeable because of the short resistor bodies and small internal distance between the ends. Operation at VHF or higher frequencies reduces the effective resistance because of dielectric losses.
Good Design Practice
Operate at one-half the allowable wattage dissipation for the expected ambient temperature. Provide an adequate heat sink. Mount no other heat-dissipating parts within one diameter. Use only in applications where a 15% change from the installed value is permissible or where the environment is controlled to reduce the resistance-value change.
The feature of this AC/DC amplifier is its low cost due to the small number of parts used. It is quite suitable for phonograph reproduction with good gain capabilities from a less sensitive pickup....
The dc amplifier in Figure P2.2 exhibits an increase in gain when there is an increase in temperature. The thermistor has resistance of 30 kl at 25°C and a B of 4000 ...
This class A headphone amplifier can output up to 0.5W into a 32-ohm headphones. I built this headphone amplifier for dynamic headphones based on my rules of proper audio design. People who know my...
As the fastest growing demand of circuit and wiring diagram for automotive and electronics on internet based on different uses such as electronic hobbyists, students, technicians and engineers than we decided to provide free circuit and wiring diagram base on your needed.
To find circuit and wiring diagram now a day its easy. E-learning through internet as a right place to search an exact circuit and wiring diagram of your choice and it's much fun and knowledgable. On internet you will find thousands of electronic circuit diagrams some are very good designed and some are not. So you have to modify them to make them according to your needs but some circuits are ready to make and require no changes.
There are many categories of circuit and wiring diagrams like automotive, audio circuits, radio & RF circuits, power supply circuits, light circuits, telephone circuits, timer circuits, battery charger circuits etc. There are many types of circuit and wiring diagrams some are very easy to build and some are very complicated, some are so small and some contain huge list of parts.
We provides free best quality and good designed schematic diagrams our diagrams are free to use for all electronic hobbyists, students, technicians and engineers. We also provides a full educational system to students new to electronics. If you are new to electronics you are a student or a electronic hobbyist and want to increase your knowledge in electronics or want to understand electronics in a very easy way so this is the right place for you we provide electronics beginner guide tutorials to easily understand complicated electronic theory. Our mission is to help students and professionals in their field.