Archive for January, 2019:

2019-01-27 Replacing Corroded Battery Contacts

From FB group Building Transistor Radios 2018-01-27 Many of the radios I’ve acquired were so corroded that I had to replace metal parts. I used tin can lids to make replacement battery holder contacts. The steel is springy enough to hold cells in place. Scissors can cut the steel, and it can be drilled and

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2019-01-20 Lower Price Radios Competition

from FB group Vintage Transistor Radios 2019-01-21 Mike van Kleeff There was a lot of pressure on domestic radios from cheaper Japanese and other imported radios. So Zenith and others had to cut costs and sell in the low price ranges. I would say that all radios, wherever they were made, were less substantial than

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2019-01-18 Tilt Wing Aircraft In The Future

From FB public comment The military had a lot of problems with their tilt wing aircraft similar to the one in the picture. The solutions often involved a lot of frequent maintenance and repair. It may not be possible to fly such aircraft profitably in a commercial airline. Another thing that’s going to change the

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2019-01-17 Power Outlets Made From Electric Outlets

From FB comment to Bill Sherman’s post Bill Sherman The cable jacket may be too big diameter to fit into the clamp. But you might consider the special 20 amp plug, the one they put on the power strips that are used in the server racks. I forget what they’re called, but we specified those

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2019-01-15 2nd FM Microphone Kit Assembled

I ordered some other FM Microphone kits, and assembled one last week. This is a better one, labeled EEQKIT RF-02FM VER170525. It has three transistors, one of which is a microphone preamp and it should perform much better. The kit also has a jack that will allow you to plug in a stereo signal from

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2019-01-11 The 1N60P “Germanium” Diode Issue

From FB group Markku Vuorensivu I bought some 1N60P “germanium” diodes and I found they are not germanium, they are Schottky silicon diodes. They do not work like germanium diodes in circuits that depend on the leakage that germanium diodes have. The Schottky or germanium diodes can be checked for reverse leakage and germanium will

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2019-01-10 The Ninth Anniversary Of The Philips LED Candelabra Lamp

On Jan 11, 2010 I connected a Philips candelabra lamp to the AC line and turned it on, and for the last nine years it has been running continually, except for a few days time when the power was out, which might add up to a few days, probably less than a week. I did

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2019-01-09 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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2019-01-08 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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