Wide Band High Frequency Amplifier Circuit

Here’s a circuit for high-frequency amplifier circuit using wide frequency band between 75-150 MHz with transistors, a PNP amplifier. To enhance the signal strength. Before the receiver of the phone. Or FM radio or amateur radio. If high-frequency signals, in particular, its VHF. The booster circuit is one, serves to amplify the signal strength only. This is the figure of the circuit;

Operation of the circuit. High-frequency range VHF, inductive antenna, to the emitter pin of the transistor Q1. so circuit held, in conjunction with the bass, a nice low output impedance. You can use a special access code 50 ohms, the antenna on the circuit at all. Signal at the Q1 will be expanded to increase. And sent to a tuner or receiver to the receiver. The L1 coil wire enamel No. 24 SWG, thousands of rounds of 10, inside diameter 3 mm. And the coil L2 wire number. Thousands of 13 turns, diameter 5 mm. Stent both as a non-core, or an air core. The power supply is +5 V, this circuit while current is 2.5 mA. If the components to use. Should be based on the antenna. And design of high frequency printed circuit boards as well.

True Stereo Indicator Circuit for Detects L-R Signal Difference

This circuit is true stereo indicator is different from what we usually find on FM radio receiver, which is usually a pilot tone detector. A stereo broadcast from FM radio station contain pilot tone, but a presence of pilot tone doesn’t necessarily a stereo broadcast signal since a mono FM transmitter ca broadcast pilot tone as well. This is the figure of the circuit;

Since this circuit to detect the difference between left and right channel, this circuit can detect a real stereophonic programs. When there is no difference between R and L input signals, the output A1 and output A2 is at the same potential. That will make a a virtual ground rail at half the supply voltage. The A1 will supply a negative or positive voltage when A1 detects a difference between R and L input signals with respect to the virtual ground rail. The C4 will be charged via D2 an C3 via D1. The LED is turned on by the comparator A3/A4 via OR circuit D3/D4. The input signal level should be greater than 100mV to compensate for the drop across D2 or D1. P1 is used to adjust the sensitivity of stereo indicator.