Archive for the ‘Oscillators’ Category:

2019-10-12 RF Oscillator Won’t Make A Sine Wave, Only Sawtooth

I wanted to make an RF Oscillator that puts out a sinewave at about 734 kHz, which uses two convenient values, 100 uH coil and 470 pF capacitor. I used the toroid core with 16 turns of 30 AWG wire, with a tap at 4 turns then later 8 turns. I built the circuit in

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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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2019-06-20

June 20 Olek Kopyto What is the reason for using higher L and lower C? For parallel resonant circuits, it’s better to use high C and low L, for series resonant it’s the other way around. Higher C means the stray capacitances of the temperature sensitive components such as the transistors have less influence on

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2019-05-29 Another Oscillator For AM Band

Also posted part to FB group Building Transistor Radios May 30 I built this coil by winding 20 turns 28 AWG enamel coated wire on a soda bottle cap. It has an inductance of about 17 microhenrys. I wound a tap for the antenna, but it would be more stable if a separate coil with

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2019-03-31

from FB group Vintage transistor Radios April 3 Are all ‘polyvaricon’ tuning capacitors the same? They’re all about the same size. Charles Vesser Japan Industry Standard… The few that I have examined were 140 pF antenna and about 70 pF oscillator. In parallel give 210 pF. They’re probably made to match up with the loopstick

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2018-12-26 UHF Oscillator

I built an oscillator using the same circuit used for the FM wireless microphone. The difference is that the capacitors and inductors are much smaller in value and the 1 transistor is a 2SC3355 which can oscillate at several gigahertz. I did this to see how high a frequency I could attain with just discrete

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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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2014-01-13 Coil For FM Microphone

I think I built one of these years ago but it must be buried in a box somewhere, probably in a pile of boxes in the garage. It’s a FM microphone transmitter, of which I have several, built from kits and from scratch. But this one was unique in that I built it with a

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