Archive for December, 2018:

2018-12-31 Measure Negative Voltage With Arduino

from FB group Arduino Projects 2018-12-31 Bharat Visualize this. You have a resistor, say 10k, connected to your 10 volt negative source. You have an opamp which has an output that can swing up to positive 10 volts. You connect this output to another 10k resistor, and connect the remaining end of that resistor to

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2018-12-31 Zenith Royal 500 Unique Issue

Also to FB group Building Transistor Radios 2018-12-31 I have several Zenith Royal 500 radios with the ‘long range’ eighth transistor added as a RF preamplifier (chassis number begins with 8). See the attached photo. This does not require a third section on the tuning capacitor, as some ‘TRF’ radios have. Zenith added a tuned

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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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2018-12-26 UHF Oscillator

I built an oscillator using the same circuit used for the FM wireless microphone. The difference is that the capacitors and inductors are much smaller in value and the 1 transistor is a 2SC3355 which can oscillate at several gigahertz. I did this to see how high a frequency I could attain with just discrete

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2018-12-25 Never Mix Batteries

From FB group Vintage Transistor Radios 2018-12-25 Nice! But if you mix batteries (old and new, used and unused, different brands) *always* remove them from the radio after use. The one with the lowest charge left will be depleted, then the others will force current through it, and it will let the juice out, and

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2018-12-24 Merry Christmas

Merry Christmas.!

2018-12-22 European Electronics In 1969

from FB group Building Transistor Radios 2018-12-22 Mike van Kleeff Most of the European radios sold in the US were probably brought in by GIs who came back from their military deployment in foreign countries. I was in Germany in ’69 and saw some European electronics and I was impressed by the performance. But what

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2018-12-18 Al And Trudy

from another blog on blogspot 2011-08-013 Saturday, August 13, 2011 Al And Trudy Al and Trudy – Aug 13, 2011 Back in the ’70s, I rented an apartment to an older gentleman who said he was a minister, and his wife. I remember her name was Trudy, and I’m somewhat sure his name was Al.

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2018-12-17 Radio Shack P-Box Kits

from FB group Building Transistor Radios 2018-12-17 Seems that what you’re saying is these P-box kits were very slow sellers, so they ended up as overstock at the surplus store. What I find odd is that I used to buy parts from RS but I can’t remember ever seeing these kits in the store. I

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2018-12-14 Voice Filter For Telecom And Radio Comm

from FB group Building Transistor Radios 2018-12-14 A voice band filter for telecomm or radio comm. The .068 or .0068 uF caps can be made by putting a 0.1 and 0.22 or .01 and .022 uF capacitors in series. The opamp can be a 1458 ‘dual 741’ opamp.

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