Tag Archives: Amplifier

Narrowband RF Power Amplifier (520MHz)

The RF power amplifier stage is usually the final active block of any electronic system that is transmitting RF power. Relatively low power RF signals are amplified to produce a more powerful signal in order to be transmitted over greater distance. RF output power can range from a few mW to MW, depend by application. RF amplifiers before were all made using vacuum tubes but modern RF amplifier nowadays uses solid state devices like MOSFET, TMOS-FET, Bipolar junction transistors, and IGBT to amplify RF signals.

This circuit features the Freescale AFT05MP075GNR1 RF power LDMOS transistor as its RF amplifier solid state device. With the use of some components and proper board layouting, Freescale was able to create a 70 watts RF power amplifier with a gain of 18.5dB. This circuit requires a 12.5Vdc power supply able to provide the maximum power this LDMOS transistor can give. In this circuit, AFT05MP075GNR1 was configured to amplify RF signal with a carrier frequency of 520MHz suitable for UHF band mobile radio applications.

The Freescale AFT05MP075GNR1 was designed for mobile two-way radio applications with frequencies ranging from 136 to 520 MHz. It can be configured as a narrowband or wideband RF power amplifier. The high gain, ruggedness and broadband performance of this device make it ideal for large-signal, common source amplifier applications in mobile radio equipment. It can operate exceptionally in a very wide temperature range, from -40 to +150 degree Celsius. Though this device handles wideband application, it can still give full power across the band.

Narrowband RF Power Amplifier (520MHz) – [Link]

KaraOkay Microphone Amplifier


Here is an all-analog, all-through-hole, cheap & cheerful preamplifier for that perennial problem of getting the microphone amplification just right, which is a challenge not only with the faithful reproduction of lead vocals during concerts and recordings, but also with campfire and karaoke-ish performances specially when the beer takes hold.

KaraOkay Microphone Amplifier – [Link]

6EM7 Single-Ended Triode (SET) Vertical Amplifier


by Matt Renaud:

What really drove me to build this 6EM7 amp was an idea about amplifier layout. Looking back at most of my tube designs, and most of those on the internet, revealed a very typical pattern. Amplifiers tended to be flat chassis with tubes and transformers above and electronics below. From a historical perspective this makes perfect sense. Metal chassis were built this way to facilitate packaging and assembly. When people started to make tube amplifiers again, they just removed the upper case and built in the same way.

6EM7 Single-Ended Triode (SET) Vertical Amplifier – [Link]

Tiny audio amp produces 1.9 W from 5 V


by elektormagazine.com:

The PAM8905 is a new audio amp chip from Diodes Incorporated measuring just 1.5 x 2.0 mm. The design operates in class D mode, achieving a total harmonic distortion of 1% (plus noise) and delivering a maximum of 1.9 W into 8 ohm using a power supply in the range between 2.8 V to 5.2 V. The PAM8905 features an integrated boost converter powering the output stage to achieve the rated output power and maintaining volume with falling battery voltage. The boost converter is a fully synchronous design, ensuring a low external component count and high efficiency.

Tiny audio amp produces 1.9 W from 5 V – [Link]

A signal amplifier module for HF


Marcus Jenkins blogged about his radio frequency amplifier project:

In building QRP HF radios, having an RF signal level amplifier building block is handy. You want 50 Ohm output impedance, some reasonable gain, supply voltage of the usual 10-14V and ease of building using standard parts from your parts bin. Some searching around the interwebs came up with a good idea for circuit from Aaron Parks, KC8FQD, who did a YouTube video on a WWV receiver.

A signal amplifier module for HF – [Link]

8-bit MCU with built-in 1 W Audio Amp


LAPIS Semiconductor has recently announced the development of a low power microcontroller that has an integrated 8-bit low power MCU core, speech synthesis circuit, highly efficient Class-D speaker amp, non-volatile memory and oscillator circuit on a single chip, making audio playback possible by simply wiring up a speaker.

The ML610Q304 has a typical audio power output of 450 mW operating at 3 V or 1 W at 5 V. The controller includes four 8-bit counters which can be combined to make two 16-bit timers, a three channel 10-bit A/D converter, a two channel SSIO, UART and I2C peripheral interfaces. The memory capacity of the ML610Q304 includes a 96 KB program flash, 2 KB data flash and 1 KB RAM. The dedicated hardware-based audio playback helps reduce CPU loading. Two suggested audio playback formats are 16 kHz 16-bit PCM and 16kHz HQ-ADPCM. The Class-D amp reduces current consumption during audio playback by approx. 40% compared to conventional solutions, making it a good choice for incorporation into mobile battery-powered devices. In recent years a growing number of electronic products are adding voice playback functionality, particularly battery-driven devices that require increased miniaturization and lower power consumption for longer operating life.

8-bit MCU with built-in 1 W Audio Amp – [Link]

Mini Stereo Audio Amplifier


The dual low power amplifier built around TDA2822 8pin DIP. IC, it is mainly designed to use in portable players, radios and other building block project. A 3V supply can be used to drive headphones providing 20mW in 32 Ohms per channel, and a 12V power supply will provide 1W in 8 Ohm per channel for small loudspeakers.

Mini Stereo Audio Amplifier – [Link]

10W Stereo Audio Amplifier


The project built around Philips TDA1521 IC, The project provides high quality audio 2X10W Audio output. The device is especially designed for mains fed applications, (e.g. Stereo TV Sound and Stereo Radio). The circuit designed for asymmetrical power supply systems.

10W Stereo Audio Amplifier – [Link]

5.5W – 2 Channel Audio Amplifier


This is a small 2 Channel amplifier constructed around Sanyo’s LA4445 IC delivers 5.5Watts +5.5 Watts at 4 ohm load, supply in 12V DC 2Amp, Input impedance 30K.


Dual Channels output : 5.5W
Minimum External Parts
Very small pop noise at the time of power supply ON/OFF
Good ripple rejections
Small residual noise
Built-in protectors 1. Thermal Protector 2. Overvoltage Surge Protector
Standard Audio signal
Supply 12V DC
Load : 4 Ohms Speaker on Each Channel
Voltage Gain : 50DB
Output 5.5W on each Channel (THD 10%)
Total harmonic distortion 1% Max @ Po=1W
Input impedance 30 K-ohms

5.5W – 2 Channel Audio Amplifier – [Link]