Party Vibe

good find 🙂 I didn’t realise it was invented by an African American; for years I thought the Japanese had invented them. Older 1950s era German tape recorders from Grundig had the type which needed a strong voltage to energise them; it was about 150V which was present on the DIN-connector for the mic – the current was limited so it wasn’t dangerous but it was easy to get bitten by it if you miswired a connection lead!

As late as 1990 many British Telecom phones still contained carbon microphones which are noisy and you had to shake up the carbon grains inside them every so often.

As well as providing much better sound quality (when using them for broadcast or music work you often have to filter out the unwanted noise) these mics are particularly good for surveillance work.

Even when monitoring a normal telephone circuit you hear all sorts of background noise as well as the conversation; so it is possible to work out where the caller is within a building from this noise (ventilator fans and other machinery, other voices, pets and animals etc)

Coincidentally I’ve got a miniature electret on my workbench recovered from modifying a hands free kit for a UHF radio (I am building an emergency comms system for use at work that uses a telephone handset with an extra button in the side to key the transmitter like 1970s govt / military service radios).

One thing to beware of when wiring these mics up is they are polarity sensitive because of the FET amplifier – if V+ is not positive you won’t hear any sound! Some equipment (many PCs, portable radios and telephones) have the resistor and elco alredy built in to the mic connection circuit.

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TBH there are way better teachers than me around and lots of learning materials online although much is buried in a sea of shit due to the “youtube culture” of trying to get views for advertising. I’ll have a look on Professor Yong’s site again; there’s a few good e-books for beginners although they aren’t free and its worth having access to a Japanese colour printer to get a hard copy. also will try and find the Japanese dudes site with loads of starter circuits.

the problem today is there is so much emphasis on “internet of things” bullshit and pretty mobile apps/GUIs it makes the learning curve very steep and often the analogue/hardware side of a lot of projects shared online contains design flaws.

in any case the best way to learn is by trying things out – at least today you don’t have to iimmediately work with strong voltages; there is also computer software that simulates electronic circuits and is becoming easier to use.

One tip my late Professor friend shared with us a few years back when explaining a complex circuit for internal telephones was “start with what you do know”‘; then relate it to the sections of the bigger systems and how they connect together..