Calculating power and output transformers using spreadsheets
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- Опубликовано: 18 сен 2024
- Had a request from one of my patrons on Patreon to explain him the process of calculating the power and output transformer using my spreadsheet calculators. In this video I show a step by step process of how I go about calculating them and optimizing them to the available options and materials.
If you would like to calculate and design your own audio and power transformer check out my spreadsheets:
www.delatsch.com/
Hi Marko! Thanks for your vids. I bought your bundle last week and look forward to winding soon! One thing though about your rec of splitting large wires into two parallel bifilars; if your calculate the cross-sectional areas of the large and smaller wires, you’ll find half-thickness wire is actually far lower than half the area of the larger wire. Two runs of 2/3 the larger wire is closer.
Hi Eric, thank you for your kind words. Hm, I never thought about that, but yeah, what you are saying seems to make perfect sense!
Thank you for the video and I'm looking forward to the new calculator.
Thank you!
Hi, what a great videos. After I've watched this one I tried to make a little sheet for my own calculations. I've replicate your steps and I've got same results as you did, but I tried to replicate the Hammond 290EX (120V 60Hz I'm from Venezuela) which seems to use EI-76.2 laminated. The window space seems to be too small for the required space used for the bobins so my calculations are wrong in some point I guess. It would be great if someday you could make another video replicating one of those Hammond transformers
The trick is that they probably use higher permeability core, so they calculate it with 12000Gs or so. The window should be 3.75x1.25cm, so around 4.69cm
@@Delatsch Ok thanks for the answer. The only way I can the make it fit the wire is using a permeability 30000Gs. The EI-76-2 window is 1.27 x 3.81 cm. My calculations:
PRIM: 120v / 0.93A / 21 AWG / 182 TURNS / 3.62 mm
SEC1: 351.20V / 0.1A / 31 AWG / 533 TUNS / 0.91 mm
SEC2: 351.20V / 0.1A / 31 AWG / 533 TUNS / 0.91 mm
SEC3 : 3.43V / 2.25A / 18 AWG / 6 TURNS / 1 mm
SEC4 : 3.43V / 2.25A / 18 AWG / 6 TURNS / 1 mm
SEC 5: 5.40V / 3A / 17 AWG / 9 TURNS / 1.1 mm
Amp X mm : 3
Gs: 30000
TURNS X VOLT: 1.52
This is the best I can do until now, I'll keep trying.
Percy
Hi, interesting output calculator. How would you use it on a Darlington single BJT class-A with a coupled transformer output into 16ohm speaker? Output power 2watt. Power supply 20v dc.
Hello Marko, I am having a hard time understanding "Selected practical core cross section (cm2)" in the Advanced PP Output Calculator. Thanks.
Hi, that is the core that you selected, the one which you have. So, the calculated is just what the optimum should be more or less, but you need to specify what you will use exactly. It is the width of the center leg of the core times the height of the stack. Or if you have the bobbin, it would be the bobbin hole length times its width.
Hi Marko! Edcor sells laminations that they say have a Gauss rating of 20,300. Would you put this really high number into your output tranny calculator or would you lower the number a little?
Hm, sounds a bit optimistic, but you can test it. Wind a simple 120V or 230V primary to 10 or 12V secondary and check if you will get the calculated voltage. Keeping the gauss level slightly lower will make the transformer run a lot cooler as well.
Hi Delatsch, thank You for the tutorial, for me especially informative is the second part - OT calculation. I bought your calculator, and trying to get to proper results - could you help me a little bit? It is a tube EL84, the amp is for audio purposes. I have EI84 cores, 2,8x42 standard bobbin. So the core cross section is 11,76, plate load is 5,2k, speaker impedance 8Ohm, Power (overrated) let's say 10W and min. frequency 50Hz. For such parameters i have primary/secondary turns like 5188/203, and stack fill of 85% (too high). In this material you said that in your experience primary should have 2000-3000 turns to have good sonic results. I can have such result by setting minimm frequency at 150Hz. Is that a proper way to calculate? Could such transformer reach - lets say -50Hz low?
Hi Jacek, something is not correct there. Please contact me on my web page or facebook.
How can I get one of your spread sheets? Is it in excel
You can get them on my website, check the links in the description, there is a new online version that works natively in browser and on this link there is a free calculator for power transformers:
transformercalculator.com
Very god
Thank you!
The website not working ?
It should be working fine, I mistyped the address and changed it now.
Marko,
Excellent video. Great to have you back.
When do you expect your “new calculator” to be available?
Thanks Robert and thank you for your support. It will be available in a few days, but I will send it you tomorrow.@@robertpichora5881