Archive for the ‘Functional blocks’ Category:

2019-09-30 RF Modulator

For the oscillator I used the Hartley oscillator circuit that is used in the Eico 330 signal generator. I didn’t need any of the range switches – I left that out. It used MPS6513 transistors which are cheap but very uncommon – I can’t remember ever seeing them in any schematics or in PC boards.

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2019-09-27 Phase Shift Oscillator For RF Signal Generator

2019-09-27 PSO I tack soldered the parts together for a PSO, and made modifications to get it go work at 500 Hz. My goal is to get a steady tone to use to amplitude modulate the RF signal generator that I have built (see this blog). The sine wave from this PSO is beautiful –

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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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2018-01-08 RF Oscillator For AM Band

For FB group Building Transistor Radios When I started building regen receivers, the first thing I found I needed was a simple  signal generator.  I have a function generator, but every time I want a different frequency, I had to readjust the controls.  So I built a few RF oscillators to put close to the

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2017-09-21 Kid Was Totally Into Telephone Central Offices

Posted to FB Antique Telephones group as a reply to Kevin J. Fitzgerald  I helped some students in our computer lab, and one high school kid, I think his name was Robert, was totally into phones.  He had written a Basic program that printed a list out, with the various exchanges in the 714 area

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