42tm117

吉田ほにお · Post by **吉田ほにお** » 26 Jan 2023, 21:31

Hello. I'm looking for xicon's 42tm117-r. Please tell me where they are sold. "If you have an extra one, I'd like you to give it to me." 　
If you know a compatible product for this transformer, please let me know. I want to create malekko wolftone chaos.

mauman · Post by **mauman** » 27 Jan 2023, 05:19

You can order here, minimum purchase is 2 pieces: https://www.tedss.com/Catalog/Browse?se ... Category=-

吉田ほにお · Post by **吉田ほにお** » 27 Jan 2023, 07:49

know here I live in Japan so I have to buy $200. I can't buy that much.

mauman · Post by **mauman** » 27 Jan 2023, 17:05

Wow, $200 USD is a lot. Here's a different solution.

Here's the schematic: viewtopic.php?p=284110

This transformer is wired with the center tapped secondary as the input, and the primary as output. The other half of the secondary is grounded. Since the TM117 impedance is 50k primary, 1k secondary, that makes the ratio approximately 50k/500, or 100:1. (see note below) The center-tapped secondary is also presenting an input impedance to the first op amp's output, so keeping the secondary impedance as high as possible would be a good idea so you don't load down the op amp too much.

Considering that, some possible substitutes might include Xicon 42TM017 (25k/600), Xicon 42TM025 (50k/1k), Xicon 42TL017 (20k/600), Triad SP-5 (50k/1k), Triad MET-01-T (200k/1k), Triad SP-4 (200k/1k), Triad SP-13 (25k/1k). These figures are for the full secondary winding, and center-tapped would be less.

Mouser Japan (mouser.jp) carries the SP-4, SP-5, SP-13, and 42TM017.

(note below: this is a ROUGH approximation, and we know the center tapped impedance is not simply half the total impedance, but I think that's close enough for this purpose...)

吉田ほにお · Post by **吉田ほにお** » 27 Jan 2023, 21:09

Hello. Thanks for the idea. Your schematic is from Studio Chaos. I want to make Marekko Chaos.
The circuit diagram is different. The secondary is not grounded in the attached image schematic. The output from the op amp is connected to the secondary center tap. 　
The center tap of the primary is connected to bias. 　
Can I use alternatives such as Xicon 42TM017 (25k/600), Xicon 42TM025 (50k/1k), Xicon 42TL017 (20k/600) in this case?

mauman · Post by **mauman** » 28 Jan 2023, 20:06

You're right, in that version, the transformer is use quite differently. Both the primary and secondary sides are center-tapped. The transformer is used to couple the signal, but in a different way than the first circuit. And both the primary and secondary are used as resistance and/or inductance for other parts of the circuit. I can't predict whether a different transformer would give you a similar sound as the 42TM117 here.