FM Crystal Radios I have heard, even from a physicist, that it is impossible to build FM crystal radios. On the other hand some experimenters claim that they have built them. This argument intrigued me to try and build an FM crystal radio, which I have done successfully. To my surprise, the result is an astounding performer, pulling in four local stations in Tucson. When connected as a receiver to a good sound system the sound fidelity is as good or better than more expensive AM radios. In fact, it sounds “high-fidelity”. Digital Clock with PIC16F84A This is a small ajustable clock, It’s made based on PIC16F84A microchip.The hardware part is very simple because it only uses 74hct238 demultiplexer, 4×7 segments, and some rezistors. The software part is programmed through a device connected to serial port with icprog and made/debuged with MPlab. 100W Guitar Amplifier Mk II This amp is rated at 100W into a 4 Ohms load, as this is typical of a “combo” type amp with two 8 Ohm speakers in parallel. Alternatively, you can run the amp into a “quad” box (4 x 8 Ohm speakers in series parallel and will get about 60 Watts. For the really adventurous, 2 quad boxes and the amp head will provide 100W, but will be much louder than the twin. This is a common combination for guitarists, but it does make it hard for the sound guy to bring everything else up to the same level. [via] Digital Voice Record and Playback Project using ISD2560P This project is based on ISD2560P IC which allows us to record 60 seconds voice and playback it with very high quality. As shown in the schematic, we input the voice by using an electret microphone. Controlling the circuit is very simple. Sw1 switches between record and playback modes. Push button B1 is used for start and pause functions. B2 stops the process. PIC16F84A Nixie Clock A very compact nixie clock based on PIC16F84A and 74141 driver IC and MPSA92 high voltage transistors. 12AU7 / IRF612 MOSFET Hybrid Headphone Amplifier A simple two stage hybrid headphone amplifier project. The voltage stage uses a vacuum tube which feeds a MOSFET follower output stage. Unlike a lot of vacuum tube projects, this one is low voltage. Both the tube and mosfets use the same 12-13V power supply. Arduino Sound Part 2: Hello World This is the second in a series of articles about generating sound with an Arduino [First Part here]. The first article covered the various methods available for sound generation with an Arduino. In this article we take a small step; “Hello World” for Arduino sound. We prepare for our future experiments by hooking up a PC or powered speaker so we can hear the Arduino sing. USB audio DAC I want to build high quality preamplifier with built-in DAC from SPDIF or USB for my power amplifier Leachamp. I had available circuit PCM2902. I tried to design DAC from USB with this circuit on one-sided PCB and I was succesful 20W Audio Amplifier using LM1875 20W Audio Amplifier kit is based on LM1875 IC. * Power supply - 48 VDC * Output - 20 W, 4 Ω * Very low distortion (THD - 0.015%), good channel separation and ripple rejection * IC built-in thermal, short circuit protections * Internal output protection diodes * Terminal pins for connecting input * Power Battery Terminal (PBT) for easy power supply and speaker connection * Power-On LED indicator * Heatsink for IC * Four mounting holes of 3.2 mm each with nut and stud * PCB dimensions 48 mm x 60 mm AVR audio spectrum monitor on graphical LCD On SG12232C graphical LCD there are two parts displayed: waveform and spectrum. It really looks cool and real when playing music. The program runs on AVR Atmega8 microcontroller clocked at maximum 16MHz frequency. The signal is passed through 8th-order elliptic filter(anti-alias filter) implemented on MAX293. Hardest part in this project was to implement an FFT algorithm which require lots of processing. But Chan has reached 9.6kHz sampling with 75Hz resolution, what is enough for visualisation. Besides firmware author also provides fixed point FFT library optimized for Atmega microcontrollers so anyone could enjoy creating similar projects. |
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