What is it you find improper? Magura's and your very own 25 lbs air core ignite the diy spirit of others into blazing bushfire. It is only a simple visit to his friendly neighborhood winder to see what is available. Hopefully he finds or is able to commission a pair he is happy with. Some old school moving core reactor AC arc welder do have cored chokes with gap adjustable through an external handle. If he is really lucky, he could end up with a pair of monumental audiophile approved, real He-Man chokes good for up to 600A.
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No Mr. MR sir, you did not say improper. Here in Indonesia, inductors are readily available off the shelf in air core crossover value variety, larger like the cored 50mH 2A for the MoFo need to be imported or specified and commissioned to a winder shop. I suppose inductor availability is pretty similar throughout South East Asia like Malaysia, Singapore and the Philippines. The welding choke bit is intended only to contrast the itty bitty SMPS filter choke he posted in #691.... Proper inductors are readily available, are they not?
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To toss some accelerant on things, I can offer a little insight on the use of the MD-803AMR-1 microwave oven transformers. If you understand the potential voltage issues on the secondary and intend to proceed anyway, based on my experience you are looking for ONLY:
MD-803AMR-1 OBJY2 E306927 with the letters GWLD after the serial number.
I have obtained four of the above for my four-channel four-ohm mofo build, and the primaries all measure 48.2 to 53.1 mH on my Sencore Z-Meter.
I also ended up with a couple MD-803AMR-1 trafos that have either GWLB or GWLC after the serial number, and while appearing identical they both measure 23-24 mH on the primary. Possibly useful for channels that are high-passed but not so much for full range.
MD-803AMR-1 OBJY2 E306927 with the letters GWLD after the serial number.
I have obtained four of the above for my four-channel four-ohm mofo build, and the primaries all measure 48.2 to 53.1 mH on my Sencore Z-Meter.
I also ended up with a couple MD-803AMR-1 trafos that have either GWLB or GWLC after the serial number, and while appearing identical they both measure 23-24 mH on the primary. Possibly useful for channels that are high-passed but not so much for full range.
Hi everyone,
I've been reading this thread with great interest from the very beginning and was intrigued by the use of MOTs as the choke in the project.
Recently found a MOT from a dead microwave oven, MOT's part # MD-701FTR-1.
It measures 3.6 ohm DCR and 312mH, measured with LIMP.
Of course all this at DC, values change with frequency, DCR goes up, L goes down.
My question to all the wise people out there is how suitable this MOT is?
How would these values, DCR and L, affect the performance of a MoFo?
I'd like to be able to afford a proper Hammond, but being a frugal person, and always willing to experiment I'm keen to give a MOT a chance.
I've been reading this thread with great interest from the very beginning and was intrigued by the use of MOTs as the choke in the project.
Recently found a MOT from a dead microwave oven, MOT's part # MD-701FTR-1.
It measures 3.6 ohm DCR and 312mH, measured with LIMP.
Of course all this at DC, values change with frequency, DCR goes up, L goes down.
My question to all the wise people out there is how suitable this MOT is?
How would these values, DCR and L, affect the performance of a MoFo?
I'd like to be able to afford a proper Hammond, but being a frugal person, and always willing to experiment I'm keen to give a MOT a chance.
So, don't worry answering my questions from above (of course you can provide answers, opinion, experience if you wish, that will be highly appreciated).
After reading and re-reading a lot of posts, info, web pages, etc. I came to the conclusion that these particular MOTs are really NOT suitable for the project.
Their high DCR means small current, maybe 1A at the most, also about 3.6V loss in Vout, therefore much reduced output power.
Not worth the effort.
Will explore other options.
After reading and re-reading a lot of posts, info, web pages, etc. I came to the conclusion that these particular MOTs are really NOT suitable for the project.
Their high DCR means small current, maybe 1A at the most, also about 3.6V loss in Vout, therefore much reduced output power.
Not worth the effort.
Will explore other options.
