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realistic 21-1175 microphone schematic?


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I owned one of those back in the 1990's and it was stolen with the 2950 it was wired up to. For what it was it was a fantastic mic. 8 years latter it was still working and I used it every single day in my mobile. I currently own the 2 of the replacement for the 21-1175 the 21-1177 which uses 2xAAA batteries instead of one MErcury 7V. I have the voice of Darth Vader so I liked this mic because it cut off some of the lows and had a very good freq. response.

The Toshiba TA7120 it used as the pre-amp was also used as an EQ in cassette decks. It does not look that impressive on paper but in real life it worked really well. It is rated for 15V so the 7V input voltage was not even close to it's limit. Like all mics like this changing the cap values changes the filter.
 
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Oh, this is heresy I have no proof this is the truth. Back in the 1990's I had a friend with benefits a Cougar if you will. She worked and my local Radio Shack in Sales she was about 28 years old and I was 19 and senior in High School. I got held back in 2nd grade because my English was not as good as my German and I stuttered and such when speaking English. Anyways she knew who made a lot of products for Radio Shack like the Optimus stuff and such if it was Pioneer, Memorex, Sony, Marantz etc....She told me that the 21-1175 was rumored to have been designed by Sony for them. I would say 75% of what she said was true and when you would take the covers off you would see Pioneer, Marantz, Sony, RCA, Magnavox, Uniden etc....on the PCB Back then it was at least as good as the Original Astatic MinuteMan and D104M6 and such not the trash-tastic thing that Astatic sells today made in China! I only owned the one but in 8 years of daily use I never had it fail not even the PTT switch.
 
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The High frequency Roll-off circuit used for NFB to Pin 3 - reminds me of using DOLBY NR to "brighten" the tape using the CRO2 Hi-Bias BASF/TDK/JVC tapes during the record, then this circuit would "punch down" those high tones into regular emphasis on the old headphones.

Ah, the good old days of riding the bus to school...

:+> Andy <+:
 
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WOW I thought that this would be a dead post when I uploaded the manual and the diagram was more than 3 years old without any response, well guys, my English is not very good, uncle google help me, I had that microphone a long time, I lost the year when I buy it I think that in the 90s I do not remember. in a radio shack store in my city, there was only a few years and it was closed, the microphone was so good, that in a couple of times I copied the circuit for 2 friends and put them in their cobra 148GTL and general electric 3-5825a ( excellent radio) the battery was hard to find, a photography store helped a few years with the battery, then I put a 9v battery, and that increase in voltage, gave rise to amplification increase, as we were CB nothing purists we loved the amplifier noise, those were good morning, the thing is that it was not coincidence that the scheme went live in a country that is now fashionable in the news, VENEZUELA, my family and I have months, picking up selling and giving away the things of our Since we must migrate to another country due to the dictatorship that was established in the country, so a whole life does not fit into a suitcase, so I decided to scan all my personal documents, and especially the manuals and agramas that I treasured during my 50 years of life, before scanning review in google if I can find it, to avoid work and this is one that happily was not found in my searches on the web and decided to upload it to this post, I hope you can give good use, greetings and good DX
 
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Thanks for stopping by, don't be such a stranger!

I used to work for the Tandy Show -er, SHOE company...

Thanks for your help for the rest of us!

:+> Andy <+:
 
Handy Andy said:
The High frequency Roll-off circuit used for NFB to Pin 3 - reminds me of using DOLBY NR to "brighten" the tape using the CRO2 Hi-Bias BASF/TDK/JVC tapes during the record, then this circuit would "punch down" those high tones into regular emphasis on the old headphones.

Ah, the good old days of riding the bus to school...

:+> Andy <+:
Click to expand...
I rode on German tour buses as school buses in High Schoo. The drivers would normally allow us to put in cassettes for the long ride to school which was often 2 hours of more each way! I had hi-end portable cassette players that had all the Dolby and the CHrome setting etc....Back then everyone made mixed tapes and had DJ gear etc.....
 
Yes I use old IC's that where intended for cassette players in the 1970's-1990's when I want to add some eq to a radio. Lot of these things where really good especially by the late 1980's and early 1990's. A lot of them had EQ, Noise Gate, Downward Expansion, Compression, Multiple independent channels that could be combined to increase gain, auto leveling of signal, all of the Dolby and Chrome EQ settings. Often the latter designs had multiple free switches built in that you could use for anything you wanted etc.
 
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