Archive for December, 2018:

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.

2018-12-12 LM78xx Linear Regulator Disadvantages

from FB group Building Transistor Radios 2018-12-13 Joseph Rotello I agree with some of your claims. But I know far more about 3-terminal regulators than you think. First off, your claim that they are more efficient is unproveable. There are linear PSes that are more efficient. That was the reason LDO regulators were used. You

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2018-12-09 Selectivity V. Sensitivity

from FB group Building Transistor Radios 2016 Dec 9 Jim Glover An ideal receiver would have a bandpass shaped like a square wave where the bandpass is flat with no attenuation and the attenuation is infinite outside of the passband. In the real world this isn’t possible but any receiver buyer with the money would

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2018 Dec 8 Sinclair Book 22 Tested Circuits Using Micro Alloy Transistors

from FB group Building Transistor Radios 2018 Dec 8 Nick Bastian posted the schematic of a Sinclair Micromatic radio. I found the book by Clive Sinclair about the circuits using micro alloy transistors. Germanium transistors and especially micro alloy transistors are no longer made so it’s better to use silicon BJTs instead. Here is the

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2018-12-04 FETs For Very Low Voltage Joule Thiefs

from FB group Building Transistor Radios 2018 Dec 4 Terry Harris I didn’t try to mimic the ALD, I used the FETs for a voltage booster. The typical 5mm LED needs somewhere around 60 mW for Max brightness. If I was powering it with 60 millivolts, it would require over an amp to get the

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2018-12-03 My Fluke 75 DMM

from FB group Building Transistor Radios Joe Lima That’s good to hear. More than a year after I bought my Fluke 75 DMM (and with light use at home) I turned the switch to off but it stayed on(!!) I had to unplug the battery. Luckily it was still under the 3 year warranty, so

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2018-12-02 How to Determine If Diodes Are Real Germanium

From comment left for Roger Kainka Labs video on YouTube Another 100% accurate method of determining if it’s germanium is how sensitive the device is to changes in temperature. The leakage current of germanium is much more sensitive to temperature changes than silicon. What angers me is that some circuits are designed with depending on

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2018-12-02 How to Determine If Diodes Are Real Germanium

From comment left for Roger Kainka Labs video on YouTube Another 100% accurate method of determining if it’s germanium is how sensitive the device is to changes in temperature. The leakage current of germanium is much more sensitive to temperature changes than silicon. What angers me is that some circuits are designed with depending on

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