Archive for the ‘Radio, Television entertainment’ Category:

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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2019-06-11 Selenium Rectifier Burned Up, How To Replace

from FB group Vintage Transistor Radios Jun 12 Bob Kirsch has the right idea, but the single replacement diode *must* be rated for 400 V peak inverse voltage or more. A 1N4007 is cheap and readily available. I assume you’re in a country where the AC line voltage is 120 VAC, because the rectified DC

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2019-05-31 DIY Plastic Variable Capacitor

I hear others complain about the high cost of variable capacitors, especially the older air variables with metal plates. So I decided to DIY and make one. This is my first attempt so forgive the lack of elegance and unfinished look. I’m sure it could be improved on and made better with some effort. The

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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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2019-05-05 Using a 7805 For An Adjustable Regulator

from FB group Building Transistor Radios Willie Barnett When you understand how the 3 terminal regulators work, you can replace the 1N4148 and the almost impossible to get 1N34 with just a pair of resistors. The 7805 or 78L05 regulator always has a fixed voltage of 5V between the O and G pins. So you

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2019-04-28 Samsung TV Remote Not Fully Functional

also FB group Building Transistor Radios 2019 Apr 28 Joe Curtis A few months ago I also bought a remote for my Samsung TV. It looked identical to my original, and the best thing about it was it’s just for Samsung so there is no setup hassles when batteries are put in – just point

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2019-04-08 Output Transformers Construction

from FB group Regenerative Receiver… Apr 8 庄议翔 The power transformers have the laminations interleaved. The first lamination has an E then I, the next one has I then E. So the transformer core does not have any air gaps, because it does not have any DC flowing through the windings. The transformers for single

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2019-04-05

from FB group Vintage Transistor Radios April 6 I clicked on the link and I looked at the schematic. I’m surprised that in 1959 they had a radio that used the OTL amplifier to drive the spkr. I remember OTL was used in the early ’60s for Hi Fi amps, but I didn’t think that

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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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2019-03-27

From FB group transistor radios Mar 29 Lin Holcomb One never knows what secrets the US government has hidden. They could have some other plans for using the WWV stations. Decades ago I worked for a radio engineer, and we had a frequency counter traceable to NBS (now NIST). He noticed that the frequency of

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