![]() The attenuator uses the 30-10-3 sequence, which provides 10dB steps between ranges. ![]() The meter presented here has a very wide frequency range, and uses a switched attenuator for range adjustment. Attach a microphone (electret mic capsules are quite good), and you have a relative sound level meter, even better if you have some way of calibration. An oscilloscope is the ideal tool, but not all hobbyists can afford the outlay for a scope, and would find justifying the not inconsiderable cost a tad difficult.Īn AC millivoltmeter - calibrated in dB - with a range of 30V down to 3mV full scale (80dB range) would be extremely useful. Digital multimeters are not useful, since they will not give the true picture of what is happening, and most have a fairly limited frequency range. When performing any tests on an audio system, some form of measuring device is essential. ![]() ![]() The article includes detailed explanations of each section (especially the attenuators, which are the heart of any test instrument). The new design has flat response to 250kHz, and while it is more complex it's a better design overall. Please note that the circuit described here has been superseded by Project 236, which covers the range from 300µV to 30V in 10dB steps.
0 Comments
Leave a Reply. |