Tagged Questions

4
votes
3answers
107 views

How do I amplify a dc voltage that is too weak to trigger the base in a transistor?

I'm trying to take the voltage output from a 3.5mm audio jack and have it light up an LED according to it's voltage. I was going to attach the left audio cable to the base of a 2222n transistor which ...
-6
votes
2answers
126 views

Simple amplifier Cuircuit [closed]

I am new in electrical transistors. My project is to make a 1 watt audio amplifier. Can anyone provide a best amplifier circuit using darlington pair and 2N3904 transistor. i searched google. So ...
2
votes
1answer
279 views

Audio Signal Switching Transistor For Shutter Release

I am a complete novice when it comes to electronics but I am trying to open a transistor when there is audio coming out of my iPod, completing the circuit for my dslr and releasing the shutter. I ...
0
votes
2answers
297 views

Power Calculation of an Amplifier

Here is a simple audio amp. Is there an easy way to calculate the power it gives? edit Resistor value, input level and speaker impedance changed.
2
votes
4answers
768 views

Common Emitter Audio Amplifier

I'm tring to build an audio amplifier. I decided to use a basic common emitter amplifier circuit as a starting point. Here it is: I have some questions about the circuit. 1-) What transistor can I ...
3
votes
1answer
376 views

How can I switch this audio jack, using its own mechanical switches, without creating feedback?

I've spent a few hours inside my car radio and I've found that when I short a hidden pin called AUX-ON to VCC, I can pipe music right into the it and it's treated like a regular AUX input. Great ...
7
votes
5answers
5k views

Simple Audio amplifier Using Transistors

I would like to build a simple audio amplifier using transistors. I know there are IC designs specifically for the task. But i want to use transistors so i can learn how to use them for amplification. ...
2
votes
3answers
640 views

How do I make this LED flasher more sensitive?

I'm making a circuit which will change brightness level of an LED in tune with music. So far, this is producing some results, but I'm not very satisfied with it: If it matters, the forward voltage ...
1
vote
1answer
371 views

What kind of resistors do I need to use in this Canon remote switch, if it is possible at all with the P2N2222A transistor I have?

I'm a total electronics n00b set out to create an intervalometer for my Canon EOS 350D camera which seemed super simple from the outset, but I got a bit blocked with creating a switch using a ...
2
votes
2answers
853 views

Low-noise audio-frequency BJT?

I found myself looking for a low-noise PNP transistor the other day. I couldn't find any parametric searches that listed noise performance. Even from the transistor manufacturers. You can search by ...
3
votes
1answer
579 views

Testing an Audio Power Amp with Paralleled Transistors

A question concerning my current repair project of an audio amp that uses big (600 W) but otherwise rather classic complementary output stages: I assume when testing an audio power amp with 6 pairs ...
3
votes
4answers
2k views

audio controlled relay circuit

I need a circuit that fires a relay when it detects audio pulses from one channel of an mp3 player. I'm going to record audio pulses in sync with the music to control a motor for mouth movement. Its ...
8
votes
6answers
2k views

Inexpensive solid-state variable resistor

I have an analog audio project I'm playing around with designs for and it will need about 150 solid-state variable resistors. I plan to control these from a micro controller so a digitally controlled ...