Archive for the ‘Building projects and kits’ Category:

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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2019-01-07 TRF Receiver Experiment

2018-01-04 also FB group Building Transistor Radios I thought that the ‘tinkerers’ who were tinkering with the loop antennas may have been getting a stronger signal because the loop antennas have a large area to capture the RF signals, so I decided to make a single channel AM Band receiver, and I chose KNX 1070

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2018-12-29 eBay, Amazon, AliExpress, etc.

from FB group Building Transistor Radios 2018-12-29 I would choose eBay over Ali-whatever. Amazon is more expensive by far. Walmart is advertising heavily here on Facebutt, but they’re more expensive too. Two alarming things have happened. I ordered parts and had to pay a tariff on them. China is retaliating for this country’s tariffs on

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2018-11-26 Two 6 uH RF Chokes

from FB group Building Transistor Radios 2018-11-26 https://archive.org/stream/ETIA1983/ETI%25201983-03%2520March_djvu.txt Two 6 uH RF chokes The photo shows two different RF chokes, each about 6.4 microhenrys. The one on the left is a ferrite bead, made by Fair-Rite, Cat. # 2643000801. These were about 12 cents apiece from Mouser.com. Yes, the wire passes through the small hole

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2018-11-25 One Transistor FM Receiver Schematic Part 1

From FB group Building Transistor Radios Larry Daniel 2018-11-26 This is the original schematic posted by Larry. GM is a gimmick capacitor made of two short lengths of solid hookup wire, twisted together for a few pF capacitance. List of RF Chokes for the ham bands Larry said he used an RCA SK1008, then corrected

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2018-11-24 The Rise Of The PCs

from FB group Vintage Transistor Radios 2018-11-24 Early on, I built and upgraded many PCs when they became popular. Some for myself and friends, but most at work. Before that I was maintaining and repairing terminals and other equipment attached to mainframe computers. It started out small with TRS-80s and Apples but really took off

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2018-11-19 Depth of Loop Antenna

from FB group Building Transistor Radios 2018-11-19 I shared my loop antenna – see photo, and it is somewhat 2 dimensional. The arms are 762mm across but the depth of the windings is only about 35 mm. Compare that to the ferrite loopstick at the other extreme, it’s 10 mm diameter but 100 mm long.

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2018-10-08 Air Band Radio Kit HMOOABRA_4.3 Part 5

from FB group Building Transistor Radios comment 2018-10-08 Bob Johansen Receive frequency? I can’t receive a signal, so the receive frequency is not known. This receiver has no tuned circuit in the RF side of the NE612, other than the bandpass filter made up of the coils on the PCB and their capacitors. The bandpass

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