mini camcorder audio hack - Page 1
Forum section: electronics / beginners

author: R005T3r
author_rank: Frequent Contributor
timestamp: September 22, 2016, 11:51:51 am
content: Hi,I have a faulty microphone on a mini camcorder that needs to be replaced. When I used the camcorder I wasn't impressed with the audio quality of the thing, so I decided to desolder the mic and replace it with a better one. Space is not an issue, because I decided to put it outside the box (with a shielded coax cable)Unfortunately there's one big problem: I have no idea what kind of microphone is, and then I don't have any experience on these type of hacking. I know for certain that it has a 4 mm diameter. Images on the second postWhat can I do to identify the microphone and hack it properly? Thanks.

author: alanb
author_rank: Frequent Contributor
timestamp: September 22, 2016, 11:57:44 am
content: it looks like an electret microphone.

author: Richard Crowley
author_rank: Super Contributor
timestamp: September 22, 2016, 12:02:46 pm
content: There is a 99.9% chance that it is a common electret condenser microphone capsule. In large quantities (as the manufacturer uses), they cost a fraction of 1€. They are available in places where electronic components are sold, such as "input transducers" for the Arduino crowd, etc.I would prefer to replace the original mic capsule with a 3.5mm jack so that you could plug in common external mic products. That would be much more convenient than having a permanently-attached cable and kludged microphone. And it would give you the flexibility of using different kinds of mics for different purposes. (Such as a clip-on lavalere or a "shotgun" directional mic on a boom, etc. etc.)

author: R005T3r
author_rank: Frequent Contributor
timestamp: September 22, 2016, 12:09:13 pm
content: That's a fantastic idea!But what can I do? I should simply solder the mono jack socket and then take a microphone and plug it on?Can I use any kind of microphone or it must be the same type? Do I need to match something in the circuit?Thanks

author: Richard Crowley
author_rank: Super Contributor
timestamp: September 22, 2016, 01:18:44 pm
content: There is an excellent chance that you can simply wire the two connections to the tip and sleeve of a 3.5mm jack and any of the 3.5mm accessories will work. No additional circuit components required. The electret condenser mic capsule requires low-voltage DC to power the internal FET transistor (impedance buffer). This is called "plug-in power" and is the common standard for all the 3.5mm connector products (including phones, etc.)However, note that phones that use TRRS connectors are not wired the same.

author: R005T3r
author_rank: Frequent Contributor
timestamp: September 22, 2016, 05:53:20 pm
content: Unfortunately I don't have any microphone, I only have a piezo disc...

author: Audioguru
author_rank: Super Contributor
timestamp: September 23, 2016, 02:18:31 am
content: An electret microphone gives good sound. It must be connected with the correct polarity, see the "mic+" and "mic-" on the pcb?. A piezo disc sounds awful as a microphone and a piezo disc can produce an output voltage high enough to destroy the circuit.

author: Zero999
author_rank: Super Contributor
timestamp: September 23, 2016, 08:20:30 pm
content: Quote from: R005T3r on September 22, 2016, 05:53:20 pmThat will not do. As mentioned above, a piezo disc will sound much worse than the original microphone.Proper electrect microphones can be bought from many suppliers.https://www.adafruit.com/product/1064http://cpc.farnell.com/kingstate/kecg2742tbl-a/microphone-electret-condenser/dp/MP34514?CMP=CPC-PLA

author: R005T3r
author_rank: Frequent Contributor
timestamp: September 24, 2016, 07:18:16 am
content: Ok, I bought a electret microphone from the local seller, Installed and shielded, with a 3.5 jack plug. I got good results: noise is almost gone, and you can clearly hear the difference.Now I've cooled down the CMOS sensor and the main BGA with an heatsink.Doing the first tests today.Also, soldering in a high density board without a microscope is very hard!