matt/main
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Compare commits

merge into: matt:main
Branches Tags
matt:main matt:patch-1
...
pull from: matt:patch-1
Branches Tags
matt:main matt:patch-1

1 Commits
main ... patch-1

Author SHA1 Message Date
mattbk
88170f9ba8 Fix MP3 link in Appendix 2024-07-03 15:00:38 -05:00
1 changed files with 2 additions and 2 deletions
Expand all files Collapse all files

4
Open-Headset-Interconnect-Standard.md
View File

@ -409,7 +409,7 @@ This simple design is included in the Standard for all to use with no obligation
* Q1: S9013, or similar NPN BJT transistor. * Q1: S9013, or similar NPN BJT transistor.
* Tests were performed (by Mark Smith in 2022-08) using an S9013 transistor, but nearly any small signal NPN BJT should work. For example, a 2N3904 (through hole) or MMBT3904 (surface mount) should work equally well. * Tests were performed (by Mark Smith in 2022-08) using an S9013 transistor, but nearly any small signal NPN BJT should work. For example, a 2N3904 (through hole) or MMBT3904 (surface mount) should work equally well.
An example recording of audio through this microphone preamp design is [here](https://halibut-electronics.github.io/Open-Headset-Interconnect-Standard/2022-08-18%20First%20Test%20Of%205%20Component%20Preamp.mp3). An example recording of audio through this microphone preamp design is [here](https://open-headset-interconnect-standard.github.io/ohis/2022-08-18%20First%20Test%20Of%205%20Component%20Preamp.mp3).
This circuit is only a slight modification of a conventional common emitter transistor amplifier, similar to what's analyzed [here](http://www.guitarscience.net/calcs/ce.htm). The difference being that we are using the 2.2k ohm resistor in the Radio side (upper right corner above) as the collector resistor. This means the top-side base resistor (R1 above) connects to the output, not to Vcc. This circuit is only a slight modification of a conventional common emitter transistor amplifier, similar to what's analyzed [here](http://www.guitarscience.net/calcs/ce.htm). The difference being that we are using the 2.2k ohm resistor in the Radio side (upper right corner above) as the collector resistor. This means the top-side base resistor (R1 above) connects to the output, not to Vcc.
@ -419,4 +419,4 @@ This circuit is only a slight modification of a conventional common emitter tran
## 7.2. OHIS to Dynamic Microphone Pad ## 7.2. OHIS to Dynamic Microphone Pad
**TODO** Document a 10 to 15dB pad to bring Electret level down to Dynamic level. Also block DC. **TODO** Document a 10 to 15dB pad to bring Electret level down to Dynamic level. Also block DC.