Archive for the ‘Uncategorized’ Category:

2019-02-19 Transistor Tester & Running From Single AA Cell

from FB group Building transistor radios 2019 Feb 19 I use a wall wart on mine. It’s a 6VDC regulated output. The tester says battery is low (it expects 7 to 9V) but it still works okay. I have a few of these, it uses a microcontroller. Notice that it runs using a single AA

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2019-02-12 FM Microphone Schematic and Parts Placement

I got three of these no name, unbranded kits from a seller on eBay. The kit comes with all parts and a PC board, but the labels on the board are R1, R2, R3… but no values for the parts. There is a schematic and photo of the completed board, but the schematic has no

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2019-02-11 The College IT Datacomm System

from FB group Bell Telephone… 2018-02-12 After the early ’80s when the RBOCs created the MPOE, all their wiring on campus became ours, and we never got any records from them of what was in the ground. On top of that we had a contractor come and install gel filled telephone cable along with ITV

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2019-02-10 Parallel Resistors Made Easy

Something that should be memorized by every technician. This also applies to capacitors in series.

2019-02-09 AA5 OPTs And Winding

from FB group Building transistor radios All the AA5 single ended OPTs I’ve taken apart have had the ‘air gap’ which is really a piece of paper. I presume that is because the DC current magnetized the core and if it didn’t have the gap it would saturate and have a lot of distortion. I

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2019-02-08 Solenoid Used To Switch a Toggle Switch

from FB group Building transistor radios Feb 11 Cool! I found one circuit that used a neat trick. They put a large value electrolytic in series with the coil, and a low value power resistor across the capacitor. When the coil is energized the full current goes through the coil until the capacitor is charged,

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2019-02-03

from FB group Orange Talk 2019-02-05 Bora Han Proko Many years ago, a Japanese organization bought or was supposed to buy the land on the corner of Main Street and Memory lane where Polly’s Pies used to be and where Mother’s Market is today. The economy went down and the big plans didn’t work out,

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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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2019-01-05 Substituting Chokes For A Coil In A Reflex Circuit

From FB group Building Transistor Radios 2018-01-15 Nick wants to use two 10 mH chokes close to each other in place of a coil that’s used in the typical reflex circuit. I’ll include a schematic of the circuit (from somewhere on the net). This is labeled L2. (begin my comment) Nick Bastian The coupling is

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