geda:transistor_guide
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geda:transistor_guide [2012/02/20 15:14] 127.0.0.1 external edit |
geda:transistor_guide [2014/04/18 12:36] vzh Add link to Russian translation |
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| + | //Translations of this page are also available in the following languages:// [[transistor_guide.ru|Русский]]. | ||
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| ====== gschem Symbol and PCB Element Transistor Guide ====== | ====== gschem Symbol and PCB Element Transistor Guide ====== | ||
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| - Have a base set of //**gschem**// transistor symbols which spans the possible (e,b,c) permutations which can exist for any given transistor package. The set of //**gschem**// symbols for npn transistors would be npn-ebc.sym, npn-ecb.sym, npn-bec.sym, npn-bce.sym, npn-ceb.sym, and npn-cbe.sym. There would be similar sets for pnp transistors and FETs (fet-sdg.sym, fet-sgd.sym, ...). Then there would be PCB elements only for actual physical transistor packages. | - Have a base set of //**gschem**// transistor symbols which spans the possible (e,b,c) permutations which can exist for any given transistor package. The set of //**gschem**// symbols for npn transistors would be npn-ebc.sym, npn-ecb.sym, npn-bec.sym, npn-bce.sym, npn-ceb.sym, and npn-cbe.sym. There would be similar sets for pnp transistors and FETs (fet-sdg.sym, fet-sgd.sym, ...). Then there would be PCB elements only for actual physical transistor packages. | ||
| - | It makes sense to me to say the second approach is obviously better. Setting up the //**gschem**// symbols is simple enough, just create the six symbols for each transistor type with the pin numbers of the emitter, base, and collector corresponding to the sequence indicated in the name. For example, the symbol npn-ebc.sym would have an emitter **pinnumber** attribute of **1**, a base **pinnumber** attribute of **2** and a collector **pinnumber** attribute of **3**. Now you only need to make PCB elements with correctly numbered pins for transistor packages as you need them and you need to have a systematic approach for naming these elements. | + | It makes sense to me to say the second approach is obviously better. Setting up the //**gschem**// symbols is simple enough, just create the six symbols for each transistor type with the pin numbers of the emitter, base, and collector corresponding to the sequence indicated in the name. For example, the symbol npn-ebc.sym would have an emitter **pinnumber** attribute of **1**, a base **pinnumber** attribute of **2** and a collector **pinnumber** attribute of **3**. Now you only need to make PCB elements with correctly numbered pins for transistor packages as you need them and you need to have a systematic approach for naming these elements. |
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| However, most TO packages do conform to a standard pin numbering convention and have a predominant number of pins and pin placement configuration. So it makes sense to have PCB elements with a particular TO name which can be used for a majority of cases. Then when a non conforming case is encountered, we can make a new TO element for it. | However, most TO packages do conform to a standard pin numbering convention and have a predominant number of pins and pin placement configuration. So it makes sense to have PCB elements with a particular TO name which can be used for a majority of cases. Then when a non conforming case is encountered, we can make a new TO element for it. | ||
| - | Here's a description of what seems to be the most common transistor outline configurations: | + | Here's a description of what seems to be the most common transistor outline configurations: |
| * //Power Transistors - Plastic//: Look at the package front (where the lettering is) with the pins pointing down. The pins are numbered left to right (1,2,3). This is very common, so it makes sense to create initial sets of three pin PCB elements with this number order using base names such as TO-126, TO-220, TO-264, etc. For variations such as a five pin TO-220 package for a LM383, you could make a PCB element with its name qualified such as TO-220-5, or maybe TO-220-T05B if you wanted to qualify it with the National Semiconductor T05B package designation for their 5 pin TO-220 package. | * //Power Transistors - Plastic//: Look at the package front (where the lettering is) with the pins pointing down. The pins are numbered left to right (1,2,3). This is very common, so it makes sense to create initial sets of three pin PCB elements with this number order using base names such as TO-126, TO-220, TO-264, etc. For variations such as a five pin TO-220 package for a LM383, you could make a PCB element with its name qualified such as TO-220-5, or maybe TO-220-T05B if you wanted to qualify it with the National Semiconductor T05B package designation for their 5 pin TO-220 package. | ||
geda/transistor_guide.txt · Last modified: 2015/01/15 15:16 by vzh
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