Archive for the ‘Electronic Design’ Category:

2018-01-09 Bootstrap Principle In Audio Amps

FB group Building transistor radios 2018-01-09 Willie Barnett That is one deficiency of your circuit: the output transistors do not have the ‘bootstrapped’ bias resistor. I’ll explain why it’s needed. In your circuit, the signal turns the driver transistor as close to off as possible. The current through the base bias resistor causes the top

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2019-01-05 Substituting Chokes For A Coil In A Reflex Circuit

From FB group Building Transistor Radios 2018-01-15 Nick wants to use two 10 mH chokes close to each other in place of a coil that’s used in the typical reflex circuit. I’ll include a schematic of the circuit (from somewhere on the net). This is labeled L2. (begin my comment) Nick Bastian The coupling is

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2018-12-22 European Electronics In 1969

from FB group Building Transistor Radios 2018-12-22 Mike van Kleeff Most of the European radios sold in the US were probably brought in by GIs who came back from their military deployment in foreign countries. I was in Germany in ’69 and saw some European electronics and I was impressed by the performance. But what

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2018-12-09 Selectivity V. Sensitivity

from FB group Building Transistor Radios 2016 Dec 9 Jim Glover An ideal receiver would have a bandpass shaped like a square wave where the bandpass is flat with no attenuation and the attenuation is infinite outside of the passband. In the real world this isn’t possible but any receiver buyer with the money would

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2018-06-28 Bootstrapped For High Z Input

From FB group Building Transistor Radios For those who don’t want to or can’t use a JFET for high input impedance, you can use a regular transistor or two and bootstrapping to get a 10 Megohm high input impedance amplifier. This is from “Common Collector Amplifiers”, Electronics Now, Oct. 1993, found at For RFs,

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2017-08-07 Protoboards And Bypass Capacitors

From FB post One important thing that people forget to do is consider what might happen with a circuit that has anything that draws power from the protoboard. If you’re working with a few low power devices such as small LEDs and switches, then there is usually not a problem. But if you have a

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