Tag: amplifier
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Arduino: 1-Watt 2m Transmitter with RF Signal Generator
Since I do a lot of RF projects, I wanted to see if I could make a 2m power amplifier using a minimal set of components. I have a number of BS170 MOSFET transistors that I’ve used for dozens of applications over the years from guitar pedal pre-amps to digital control circuits. I started this…
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7MHz Transmitter with AVR Soft-keyer
In my last post, I went over the design of a Colpitts crystal oscillator design that put out a moderately clean 7 MHz signal. In order to match the output impedance to 50 Ω, an NPN feedback pair (at least that’s what I’m calling it) was designed. While meeting the specs for driving an ADE-1…
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Basic Voltage-Controlled Amplifier
I’ve been looking at the theoretical principles that govern the voltage-controlled amplifier (VCA) recently and came across some simple VCA designs that caught my attention. A common technique involves a JFET and an opamp to achieve VCA type operation by using the JFET as a voltage-controlled resistor somewhere in the input path. I’ve seen a…
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Class AB amplifier test
this was an attempt at designing a simple transformer-less class AB amplifier using two BJT power transistors. i setup the USB fan to protect against thermal runaway and cool off the transistors during operation. it took me looking over several schematics to realize that the the emitters of both the PNP and NPN transistors were…
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solid-state tremolo for tube amps…
i’ve have a CBS-era Fender Bantam Bass in for repair that looks like a bowl of spaghetti inside the chassis. it’s a slew of yellow wire spread from one side to the other that resembles the web of a drunken spider. the amp has been modified to include a tremolo, reverb, and an effects loop…
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no. 5 re-appropriation…
this is a re-appropriation of a Fender Frontman 15-B. it’s one 8″ speaker in a closed cabinet primarily designed as a really cheap bass amp to be included in starter packs. having gutted the amp a few years ago and replaced it with the contents from the No. 5 tube amp project, i got some…
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TDA2040-based amp schematic with EQ…
well here’s the first draft of the simplest medium powered solid state design i could muster. TL082 can easily be substituted with a TL072 which is probably better anyhow (i just have all these TL082s laying around). the power supply i’m using more like 14-15V. both ICs should easily be able to handle up to…
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TDA2040 amp prototype…
prototype of a 20-watt TDA2040 based amplifier that i’ve been working on. running a 12-volt power supply and it’s surprisingly loud.