Trash or treasure. What are these diy bits of test gear? - Page 1
Forum section: electronics / testgear

author: RichardM
author_rank: Frequent Contributor
timestamp: November 06, 2023, 08:34:00 am
content: For $5 thought it was worth the risk. Some sort of audio passive filtering tests?

author: alm
author_rank: Super Contributor
timestamp: November 06, 2023, 08:40:27 am
content: The top and probably bottom unit in the first picture have an output W+F meter. My guess is that this stands for wow and flutter meter, which was a meter commonly used when servicing analog tape systems.

author: RichardM
author_rank: Frequent Contributor
timestamp: November 06, 2023, 10:07:03 pm
content: Thanks for the reply. I ran a signal through and the cut-off filtering still works. May be some parts worth salvaging. Those glass capacitors look interesting and measure amazingly on my lcr meter across the range of frequencies. They may work well in other audio projects. I will do some reading and also try to work out how to categorise those output transformers when they have no markings etc.Richard

author: tautech
author_rank: Super Contributor
timestamp: November 06, 2023, 10:41:04 pm
content: Quote from: RichardM on November 06, 2023, 10:07:03 pmThe Trimax ones ?They appear to be impedance matching types and are clearly marked.

author: wasedadoc
author_rank: Super Contributor
timestamp: November 06, 2023, 10:57:47 pm
content: The "glass capacitors" are not glass but polystyrene film. eghttps://docs.rs-online.com/03b5/0900766b8157e132.pdfNot so common now but I routinely was using them in the 1970s. Our component stores also had various sizes of those coil assemblies for making your own coils and transformers. I think they were Mullard branded. Part of the Philips group.

author: RichardM
author_rank: Frequent Contributor
timestamp: November 06, 2023, 11:34:29 pm
content: No not the Trimax ones, the other unmarked transformers on the other 2 boxes. They appear to be on the input ?Ok, not glass, understood. Still worth keeping ? Not cheap. Thanks again.

author: tautech
author_rank: Super Contributor
timestamp: November 06, 2023, 11:39:51 pm
content: Quote from: RichardM on November 06, 2023, 11:34:29 pmPrimary and secondary resistance measurements ?

author: RichardM
author_rank: Frequent Contributor
timestamp: November 07, 2023, 04:00:07 am
content: 23.3:23.6 ohms

author: tautech
author_rank: Super Contributor
timestamp: November 07, 2023, 04:03:33 am
content: Quote from: RichardM on November 07, 2023, 04:00:07 am~1:1 Isolation xformer. On the inputs you said ?

author: RichardM
author_rank: Frequent Contributor
timestamp: November 07, 2023, 04:13:27 am
content: Yes it does appear to be on the input of the large headphone jack. I will check again.

author: RichardM
author_rank: Frequent Contributor
timestamp: November 07, 2023, 11:56:17 am
content: A general question, when do you need to use a 1:1 audio transformer ? i.e. what applications ? All of these transformers, including the Trimax, appear to be 1:1 transformers.Cheers

author: Kleinstein
author_rank: Super Contributor
timestamp: November 07, 2023, 12:37:42 pm
content: The polystyrene capacitors may be worth keeping, though at least the smaller ones are usually not that expensive. The start to become hard to get though.Most of the properties (especially the leakage current) are good, but they are sensitive to chemicals (even alcohol may damage them) and heat.In many application one can now use C0G MLCCs instead. There main use now is for very low leakage, e.g. in electrometers, pA meters.Audio transformers can be usefull to avoid hum from ground loops, e.g. when combining many parts that are grounded.

author: Grandchuck
author_rank: Super Contributor
timestamp: November 07, 2023, 01:14:09 pm
content: Quote from: RichardM on November 07, 2023, 11:56:17 amOne use is testing radio station audio performance. The audio signal generator is connected to the console using a 1:1 transformer. This keeps power line hum (caused by ground loops) and other artifacts from degrading the signal to noise ratio. Many years ago I used such a transformer in a proof of performance verification for a commercial FM broadcast station.

author: themadhippy
author_rank: Super Contributor
timestamp: November 07, 2023, 01:43:31 pm
content: QuoteNot so common these days with the introduction of digital system,but back in the days of anologe pa systems they were often found splitting the feeds from stage to the monitor desk,foh desk,recording truck,tv feed etc.