16:18 31/12/2003 OPT_da Yves Monmagnon@wanadoo.fr INSTALLATION Create a new folder, says "OPT_da" Unzip the uploaded file into. This will create two subfolders: "Install" and "Samples". Open the "Install" subfolder and execute "Startup.exe", follow intructions. "Install" subfolder is no longer necessary. This is the "Standard Microshit" method. If you already use VB6 you may not need to load all those huge files. Sources files are available too (so you can see how dirty there are) but you have to recompile. PURPOSE This program doesn't pretend to compute the better output transformer, it simply helps you to design the one which best fits your needs in assisting among infinite iterations. DISCLAIMER (I even doubt of my incertitudes) Great care was taken to make computation as precise as possible, however we don't live in a perfect world. First at all, I'm less than perfect. Predicting exactly how a transformer will work should (perhaps) be possible if it could be build exactly as specified. Some formulae are of the "cook receipt" type, specially for leakage inductance and parasitc capacitance. Steel and copper specifications are subject to manufacturer's tolerance, winding execution and core assembly are very prone to deviations. Will the insulation thickness between copper layers be exactly respected ? Will the exact gap height respected ? Will the expected quantity of steel be inserted in the bobbin ? What kind of hardware wil be used in final assembly ? Is bell (or chassis) magnetic material ? Does it short out the gap ? Are you sure the sound that reach your ears through your loudspeakers is not affected by atmospheric pressure nor air moisture ? So long ! Consider results from this program for what there are: a reasonnable starting point and don't worry too much about subdecimals. APOLOGIZE Sorry, my brain is unable to think in square mils, wire gauge nor cubic inches. STARTING Launch programm as usual by double clicking on its icon or, from the file manager, by double clicking on "OPT_da.exe" The worksheet shows five frames: The Green one is where you enter main specifications. The Orange one give results about winding and it's where you may alter wire size and turns. The Grey one give infos about core, and allow to select another one. The Blue one is where you enter data about insulation. The Purple one gives some useful additional infos about real load. The White one may receive free text. If it is the first launch, default specs (in the green window) are as follow: 20 hz lowest frequency 10W 700 Ohms tube's Rp Single Ended configuration checked 3800 Ohms primary in four sections A DC plate current of 60 mA 6 Ohms secondary with 5 paralleled wires a 0.2 mm gap (for SE operation) From this specs, a solution is suggested, core data being taken from a small database (more about that latter). And now, YOU play ! Of course, you can change all default specs, but you can also alter: Standard Wire gauge Click in the 'Diameter' text box, replace by a new value and 'Enter' Recalculations are immediate. Look at the upper right of the orange frame if the winding still fits in the 'copper window' ********************************************************************************************** * BE CONSERVATIVE: The real quantity of copper that fits depends heavily of winding quality. * * Do some tests before real work, nothing more frustrating than an over filled bobbin !! * ********************************************************************************************** The value for 'Insulation Thickness Max allowed' takes care of the number of sandwich slices which is the consequence of the number of sections in each winding. It indicates how thick insulation can be between each slice, use a lower "Actual" value. Losses in copper (at specified power) are shown at the bottom center of the orange frame. The 'AC Only' value ignore the DC component. Increasing wire size reduces losses but quickly overfill the copper window. Primary Inductance Is shown in Henrys above the scroll bar at the upper center of the orange frame. Use scroll bar to change it as needed, recalculations are immediate. Core size When no other compromise is possible to fit all necessary copper, you may choose a larger core by double clicking on the desired core name in the list (Grey frame). Core name now appears in red, click on it to return at the suggested. You may choose to accept an higher lo frequency cut off (EG. 80 Hz for a guitar amp) that will allow for a smaller core. Another compromise is to permit higher induction, resulting in risk of saturation at lower frequency. The induction value is given for the rated power at lowest frequency, this condition seldom occurs in real world. It's up to you ! Interleaving In the green frame, both primary and secondary winding may be divided in "Sections" and "Wires". One section means this winding is not fractionned, two sections means the winding is divided in two halves, and so on. More than one wire means that the winding is in fact constitued by more than one windind to be tied in parallel. This affects the "Shunt Cap", the "Leak L" as well as the "Fo" values shown in the blue frame according to the insulation thickness and dielectric constant. Actual load The table in purple frame shows the actual load reflected at the primary according to the frequency and the real secondary load incuding wire resistance, primary inductance and leakage inductance. It should be fine to separate the real and imaginary components but this is well over my math competences. Help needed ! You may iterate as long as you are not satified. Beep warns you if something goes too wrong. Design may be saved at any time with same or different name. More than one worksheet can be launched at a time to easily compare solutions. When you launch a new worksheet, it spawns with the more recently saved values. You may simulate a single choke by leaving secondary impedance blank. Information about parasitic capacitance and leakage inductance are then meaningless SIMULATION You may want to see what happen at different frequencies or power level for the actual winding. To do that, click on "Turns per Volts" text to lock the actual winding so it will not be recalculated. Click again to return to normal processing. CORE DATABASE Core data are stored in a small ACCESS(TM) database. Existing samples may be updated or deleted as well as new core may be created. Use the "Edit HighLighted core" button to open the edit window. You may then alter existing values. To create a new entry, type a new name in place of the current one and strike TAB key. If it not allready exists you will be prompted to accept saving current values under this new name. At this time you have just created an 'alias', now alter values as needed and click on the "Save" button. You may also alter values first and then change name. Note that if you enter an existing name, values for this core is displayed. Cores are named according european convention, eg. EI96 is an 96 mm width EI stack having a (96/3 =) 23 mm tongue width. Indices (A,B,C) where present denotes various stack height. Permeability is derived from a lookup table beleived to be valid for M6X laminated EI steel and is not modifiable (for now) mainly because I've no useful informations about different materials or geometry. And a splendid time is garanteed for all !