Electronics and Technical resources from vu3dxr
The Terminated mini loop antenna is a relatively simple antenna to construct. It can provide the user with wide/multi band access (160-6 Meters), without the need for a tuner. These antennas combine elements of loop and terminated designs to achieve directional reception with reduced noise pickup. Unlike large loop antennas, which require significant space, mini loops …
Recently, I acquired a uBITX v6.1 transceiver at the Lamakan 2024 event. However, due to a busy schedule, I left it idle for some time. When I finally decided to power it up over the weekend, I encountered an unexpected issue: the audio quality was extremely poor. The received audio was chirpy and unpleasant, though …
Microphone compressor using LM1458 The LM1458 is a dual operational amplifier (op-amp) that finds applications in audio amplification and other circuits. Let’s explore how you can create a simple microphone preamplifier with compression using the LM1458. To get greater transmitting performance from your ham radio transceiver, we need to keep the modulation level constant, regardless of …
Condenser Mic audio amplifier The compact, low-cost condenser mic audio amplifier described here provides good-quality audio of 0.5 watts at 4.5 volts. It can be used as part of intercoms, walkie-talkies, low-power transmitters, and packet radio receivers. Transistors T1 and T2 form the mic preamplifier. Resistor R1 provides the necessary bias for the condenser mic …
Dual microphone noise cancellation using LF351 Op Amp Dual microphone noise cancellation (also known as Dual Mic ANC) is a technique used to improve the quality of audio captured by microphones in noisy environments. This circuit dual microphone noise cancelling using LF351 Op Amp uses two mics back to back, each amplified, one inverted, and …
Series Modulated AM Transmitter A series modulated AM Transmitter is a type of radio transmitter that uses amplitude modulation (AM) to transmit audio signals over a carrier wave. It’s known for being low-power and simple to construct, making it a good option for beginners or those interested in QRP (low-power) applications. In a series-modulated AM …
Class E – AM Transmitter A Class C AM transmitter is a type of high-efficiency, solid-state transmitter that is popular among amateur radio enthusiasts. It is known for its simplicity, affordability, and efficiency compared to other types of transmitters. Unlike Class E’s switching operation, Class C amplifiers operate in a more “on or off” manner. …
Noise Canceling Condenser Microphone Noise Canceling Electret condenser microphones are a great choice for noise-canceling applications due to their small size, low power consumption, and high sensitivity. They work in conjunction with active noise cancellation circuitry to create a more peaceful listening experience. Electret condenser microphones (ECMs) can be very effective for noise cancellation when …
