Archive for the ‘Building projects and kits’ 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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2019-07-06 Earliest Audio Amplifiers I built

from FB group Building Transistor Radios July 6 Bill Korbak The early germanium alloy transistors didn’t have enough bandwidth for RF, they were only good for audio. That’s where I built my first amplifier, a three transistor audio amp on a PC board I etched in ferric chloride. I also built the power amplifier. It

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2019-06-12 Plug-in Coils Pros And Cons

from FB group Regenerative Radio… Jun 13 I’ve thought about using plug-in coils, but I’ve had experience with Grid dip meters and there are a few important issues that must be dealt with. One is, what happens to the unused coils when the equipment is not in use. They get separated from the equipment and

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2019-05-25 Books Insult Your Intelligence

from FB group Building Transistor Radios May 25 Loren Moline I don’t think the book insults your intelligence. The book itself is often written with subset of readers in mind such as beginner, professional, mathematics challenged, etc. It’s the failure of the book advertising to make that clear. I believe the book advertising hypes every

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2019-05-19 No Go Showboat

from FB group regenerative receiver initiative May 22 Henrik Stenstrom I would like to build something hollow state with all sorts of gizmos like in this photo, but all of it would be a no-go showboat, just for looks. I would put Amber or orange LEDs under the tubes to make them look like they’re

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2019-03-07 Make a 4 Millihenry RF Choke

From FB group Building Transistor Radios Mar 7 I got some of these toroid cores a few months ago, and I got around to experimenting with them. I wound one with 21 inches (51 cm) of 30 AWG (.25 mm diameter) enameled wire. This covered the core with a single layer of wire. I measured

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2019-02-05 Floating Detector Diodes Are Not A Good Design.

from FB group Building Transistor Radios 2019-02-05 Graeme Heal Aaron Cake has a lot of good circuits and projects. But this one uses the ‘floating detector diode’ with no DC return path, so the circuit will only work if the diode’s leakage current provides the discharge. That means the diode must be germanium, not silicon,

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2019-01-08 99 Cent Wireless Microphone Kit Assembly

2018-01-08 also FB group Building Transistor Radios Before the Xmas holidays I ordered a few of these at 99 cents apiece, and they gave a delivery date of late Jan to early Feb, so I was pleasantly surprised to get them early. There are many of these single transistor microphones around, either as schematics or

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