Re: uBITX Audio Breakout Plus board... #ubitx

Paul Galburt - K2AYZ

The LM324 is a rock solid device and has been around for decades. It is a bit noisy (35 nV/Hz^-2) and has a low slew rate (0.7V/uS). This means that at 8 volts peak audio, it will become slew rate limited at 10KHz. This is all acceptable for speech in a radio. The LM324 can handle much higher supply voltages (32V) than are seen in the uBitx design. About $0.50 each.

The TLC274 is has a higher slew rate (3.6V/uS) and will never slew rate limit. Oddly, it has a lower gain-bandwidth product (0.32 MHz vs 0.7 MHz) and a slightly lower noise (25nV/Hz^-2). But, the maximum power voltage is 16V. It costs about $1.60

My choice would be to use the LM324 all around for modest gain speech frequency audio and DC applications.



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