Search Results
27MHz Fm Narrow Band transmitter
NBFM or Narrow Band Frequncy Modulation is used in this 27 MHz fm transmitter circuit schematic. This circuit is an application by Motorola MC2833 - VHF transmitter with FM modulation and narrow band in a single chip.
The output power is 10mW (+10 dBm) and the coverage is 10 - 20m.
P1 is used to adjust microphone [...]
Microphone amplifier with low noise
This low noise microphone amplifier is build with MAT02 produced by PMI. This mic amplifier is very performant and has a very low noise level. The amplification can be 20dB or 23.5dB (10x or 15x ) selected by S1.
The output impedance is 70 Ω at 23.5 dB gain and with R3 = 220KΩ the input [...]
Intercom circuit, intercom schematic
In this intercom schematic, the 8 ohm speakers is used as microphone and listening speaker.
The 10K potentiometer controls volume and the total gain can be set with de 5k R. Use a double switch with 2 positions so when one is used to talk and the other one to listen. The switch will be in [...]
