Difference between revisions of "Transformers"
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| + | ==Basics== | ||
| + | |||
| + | ===Calculating Number of Turns, Core Size, and Wire Needed=== | ||
| + | N&V 2020-5. Tech Forum, there are some equations and a chart. See the example given. Also consider starting with an existing transformer, keeping the primary and rewinding only the secondary. | ||
==Tips/Techniques== | ==Tips/Techniques== | ||
===Measuring Capacitance between Windings=== | ===Measuring Capacitance between Windings=== | ||
There are expected values. Consider the capacitance may differ based on frequency per [[Capacitors]]. | There are expected values. Consider the capacitance may differ based on frequency per [[Capacitors]]. | ||
| − | See: https://www.eevblog.com/forum/chat/custom-r-core-transformers-on-ebay/ | + | See: https://www.eevblog.com/forum/chat/custom-r-core-transformers-on-ebay/ This thread also links to a few places where you can |
| + | buy custom made ones. | ||
===Hi Pot testing=== | ===Hi Pot testing=== | ||
| − | breakdown voltage of the windings. For 120V mains transformers it's around | + | breakdown voltage of the windings. For 120V mains transformers it's around 1200Vrms (maybe i think 1500V). See https://www.youtube.com/watch?v=NhWkxIBGkCM Lots of youtube videos on hi pot testing. /archive /2023_03. |
| − | |||
| + | ===Faraday Shields=== | ||
| + | They can be built different ways, connected to different windings | ||
| + | * https://canadatransformers.com/faraday-shield | ||
| + | * http://web.archive.org/web/20240228180910/https://canadatransformers.com/faraday-shield/ | ||
| + | ===Disassembly Should Not Destroy Them=== | ||
| + | separating them, then reassembling should not destroy them if done properly. | ||
| + | Use a proper measuring tool (calipers, micrometer) to get the before disassembly | ||
| + | and after disassembly distance between the cores. | ||
| + | * https://www.eevblog.com/forum/projects/heated-ferrite-useless-ferrite/ | ||
| + | * https://electronics.stackexchange.com/questions/497489/temperature-degradation-of-ferrite-cores | ||
| + | Mention of diodes gone wild. When in doubt of the before / after performance, make some measurements. | ||
[[Category:online notes]] | [[Category:online notes]] | ||
Latest revision as of 23:29, 16 February 2025
Basics
Calculating Number of Turns, Core Size, and Wire Needed
N&V 2020-5. Tech Forum, there are some equations and a chart. See the example given. Also consider starting with an existing transformer, keeping the primary and rewinding only the secondary.
Tips/Techniques
Measuring Capacitance between Windings
There are expected values. Consider the capacitance may differ based on frequency per Capacitors. See: https://www.eevblog.com/forum/chat/custom-r-core-transformers-on-ebay/ This thread also links to a few places where you can buy custom made ones.
Hi Pot testing
breakdown voltage of the windings. For 120V mains transformers it's around 1200Vrms (maybe i think 1500V). See https://www.youtube.com/watch?v=NhWkxIBGkCM Lots of youtube videos on hi pot testing. /archive /2023_03.
Faraday Shields
They can be built different ways, connected to different windings
- https://canadatransformers.com/faraday-shield
- http://web.archive.org/web/20240228180910/https://canadatransformers.com/faraday-shield/
Disassembly Should Not Destroy Them
separating them, then reassembling should not destroy them if done properly. Use a proper measuring tool (calipers, micrometer) to get the before disassembly and after disassembly distance between the cores.
- https://www.eevblog.com/forum/projects/heated-ferrite-useless-ferrite/
- https://electronics.stackexchange.com/questions/497489/temperature-degradation-of-ferrite-cores
Mention of diodes gone wild. When in doubt of the before / after performance, make some measurements.
