electret microphone transistor amplifier

The final results are impressive, and this project would make a great entry into the DIY microphone space for anyone eager to start building their own gear. There’s also a saddle on Shapeways that’s designed to neatly mount the electret capsule within the housing. The circuit is designed to fit inside a common BM700 or BM800 microphone body, and the PCB can be ordered from PCBWay for those interested in building their own. This means the microphone needs no batteries, and using a dual op-amp enables the circuit to properly drive a balanced audio connection. Instead, this design relies on a dual OPA1642 op-amp, with its low quiescent current meaning it’s perfect for running off phantom power. had used FETs in the past, but grew tired of routinely having to hunt for obsolete parts.

The goal of the project was to create a circuit to match the TSB2555B electret capsule that could be used with phantom power, and that could be built with easily obtainable parts. is a big fan of these microphones, and decided to build a high-quality, easy to use circuit that he has shared with the community. Instead, they require special high-impedence circuitry to extract the audio signal for recording.

However, unlike other types, they can’t simply be plugged directly into a mixing desk. I was wondering where one would add a potentiometer for a volume control to this.Electret microphones are capable of high-quality output, and are prized for their smooth frequency response. The dynamic mic should work in the same place in the circuit as an Electret mic. I have not tried it with dynamic mic, however in a similar circuit I have used a magnetic pickup coil in the same location where you would place the dynamic mic. I have used this circuit with Electret mics with pleasing results. A balance is established at the 'sweet spot' of the transistor where any perturbation on the Emitter of the transistor is amplified at the Collector of the transistor and in phase with the Emitter. By turning ON, the trickle power is quenched causing the transistor to turn OFF. The idea is that the 10uF Capacitor trickle charges through the 10k and the 47k until it reaches a point that the transistor turns ON. This is of my own design using an Emitter follower configuration and a self biasing technique to place the transistor in it's most sensitive linear region (exactly where you want it for an Audio pre-amp). Here is a nice hobbiest explanation of transistor characteristics. You want a voltage gain of around 40dB, which is 100x. The gain of this circuit we are talking about with the emitter grounded will depend very much on the gain (Hfe, beta) of the transistor itself.

If you have a bag of 2N2222A's, I suggest you take out your ebay component tester and find a pair of transistors for your stereo amplifier that are fairly well matched in terms of Vbe and gain, and pass up on ones that have an exceptionally low gain. All said, the rockers are not going to bring their most discriminating ear, am I right? A better audio choice would be something like the 2N5088 or the BC547B specified in the article, which are designed for low level like audio with a noise figure around 2dB. It is roughly comparable to a 2N3904, which does list one around 5dB. For example, it usually does not list a noise figure on its data sheet. It not usually thought of as a small signal amplifier though.

Electret microphone transistor amplifier